In this short blog post, I will share a few ansible tips:

Run a specific role

ansible -i hosts -m include_role -a name=roles/common all -b

Print Ansible Variables

ansible -m debug -a 'var=vars' 127.0.0.1 | sed "1 s/^.*$/{/" | jq .

Ansible Conditionals

Variable contains string

matching string in a variable

  vars:
      var1: "hello world"

  - debug:
        msg: " {{ var1 }} "
    when:  ........

old way

  when: var1.find("hello") != -1

deprecated way

  when: var1 | search("hello")

Correct way

  when: var1 is search("hello")

Multiple Conditionals

Logical And

      when:
        - ansible_distribution == "Archlinux"
        - ansible_hostname is search("myhome")

Numeric Conditionals

getting variable from command line (or from somewhere else)

   -  set_fact:
       my_variable_keepday: "{{ keepday | default(7)  | int }}"

    - name: something
      debug:
        msg: "keepday : {{  my_variable_keepday }}"
      when:
        - my_variable_keepday|int >= 0
        - my_variable_keepday|int <= 10

Validate Time variable with ansible

I need to validate a variable. It should be ‘%H:%M:%S’
My work-around is to convert it to datetime so that I can validate it:

  tasks:
    - debug:
        msg: "{{ startTime | to_datetime('%H:%M:%S') }}"

First example: 21:30:15

True: "msg": "1900-01-01 21:30:15"

Second example: ‘25:00:00′

could not be converted to an dict.
The error was: time data '25:00:00' does not match format '%H:%M:%S'

 

This article will show how to install Arch Linux in Windows 10 under Windows Subsystem for Linux.

WSL

Prerequisite is to have enabled WSL on your Win10 and already reboot your machine.

You can enable WSL :

• Windows Settings
• Apps
• Apps & features
• Related settings -> Programs and Features (bottom)
• Turn Windows features on or off (left)

 

 

Store

After rebooting your Win10, you can use Microsoft Store to install a Linux distribution like Ubuntu. Archlinux is not an official supported linux distribution thus this guide !

 

Launcher

The easiest way to install Archlinux (or any Linux distro) is to download the wsldl from github. This project provides a generic Launcher.exe and any rootfs as source base. First thing is to rename Launcher.exe to Archlinux.exe.

ebal@myworklaptop:~$ mkdir -pv Archlinux
mkdir: created directory 'Archlinux'

ebal@myworklaptop:~$ cd Archlinux/

ebal@myworklaptop:~/Archlinux$ curl -sL -o Archlinux.exe https://github.com/yuk7/wsldl/releases/download/18122700/Launcher.exe
ebal@myworklaptop:~/Archlinux$ ls -l
total 320
-rw-rw-rw- 1 ebal ebal 143147 Feb 21 20:40 Archlinux.exe

 

RootFS

Next step is to download the latest archlinux root filesystem and create a new rootfs.tar.gz archive file, as wsldl uses this type.

ebal@myworklaptop:~/Archlinux$ curl -sLO http://ftp.otenet.gr/linux/archlinux/iso/latest/archlinux-bootstrap-2019.02.01-x86_64.tar.gz

ebal@myworklaptop:~/Archlinux$ ls -l
total 147392
-rw-rw-rw- 1 ebal ebal    143147 Feb 21 20:40 Archlinux.exe
-rw-rw-rw- 1 ebal ebal 149030552 Feb 21 20:42 archlinux-bootstrap-2019.02.01-x86_64.tar.gz

ebal@myworklaptop:~/Archlinux$ sudo tar xf archlinux-bootstrap-2019.02.01-x86_64.tar.gz

ebal@myworklaptop:~/Archlinux$  cd root.x86_64/

ebal@myworklaptop:~/Archlinux/root.x86_64$ ls
README  bin  boot  dev  etc  home  lib  lib64  mnt  opt  proc  root  run  sbin  srv  sys  tmp  usr  var

ebal@myworklaptop:~/Archlinux/root.x86_64$  sudo tar czf rootfs.tar.gz .
tar: .: file changed as we read it

ebal@myworklaptop:~/Archlinux/root.x86_64$ ls
README  bin  boot  dev  etc  home  lib  lib64  mnt  opt  proc  root  rootfs.tar.gz  run  sbin  srv  sys  tmp  usr  var

ebal@myworklaptop:~/Archlinux/root.x86_64$ du -sh rootfs.tar.gz
144M    rootfs.tar.gz

ebal@myworklaptop:~/Archlinux/root.x86_64$ sudo mv rootfs.tar.gz ../

ebal@myworklaptop:~/Archlinux/root.x86_64$ cd ..
ebal@myworklaptop:~/Archlinux$ ls
Archlinux.exe  archlinux-bootstrap-2019.02.01-x86_64.tar.gz  root.x86_64  rootfs.tar.gz

ebal@myworklaptop:~/Archlinux$
ebal@myworklaptop:~/Archlinux$ ls
Archlinux.exe  rootfs.tar.gz

ebal@myworklaptop:~$ mv Archlinux/ /mnt/c/Users/EvaggelosBalaskas/Downloads/ArchlinuxWSL
ebal@myworklaptop:~$

As you can see, I do a little clean up and I move the directory under windows filesystem.

 

Install & Verify

 

Microsoft Windows [Version 10.0.17134.619]
(c) 2018 Microsoft Corporation. All rights reserved.

C:UsersEvaggelosBalaskas>cd Downloads/ArchlinuxWSL

C:UsersEvaggelosBalaskasDownloadsArchlinuxWSL>dir
 Volume in drive C is Windows
 Volume Serial Number is 6C02-EE43

 Directory of C:UsersEvaggelosBalaskasDownloadsArchlinuxWSL

21-Feb-19  21:04    <DIR>          .
21-Feb-19  21:04    <DIR>          ..
21-Feb-19  20:40           143,147 Archlinux.exe
21-Feb-19  20:52       150,178,551 rootfs.tar.gz
               2 File(s)    150,321,698 bytes
               2 Dir(s)  374,579,486,720 bytes free

C:UsersEvaggelosBalaskasDownloadsArchlinuxWSL>Archlinux.exe
Installing...
Installation Complete!
Press any key to continue...

C:UsersEvaggelosBalaskasDownloadsArchlinuxWSL>Archlinux.exe run uname -a
Linux myworklaptop 4.4.0-17134-Microsoft #523-Microsoft Mon Dec 31 17:49:00 PST 2018 x86_64 GNU/Linux

C:UsersEvaggelosBalaskasDownloadsArchlinuxWSL>Archlinux.exe run cat /etc/os-release
NAME="Arch Linux"
PRETTY_NAME="Arch Linux"
ID=arch
BUILD_ID=rolling
ANSI_COLOR="0;36"
HOME_URL="https://www.archlinux.org/"
DOCUMENTATION_URL="https://wiki.archlinux.org/"
SUPPORT_URL="https://bbs.archlinux.org/"
BUG_REPORT_URL="https://bugs.archlinux.org/"

C:UsersEvaggelosBalaskasDownloadsArchlinuxWSL>Archlinux.exe run bash
[root@myworklaptop ArchlinuxWSL]#
[root@myworklaptop ArchlinuxWSL]# exit

 

Archlinux

C:UsersEvaggelosBalaskasDownloadsArchlinuxWSL>Archlinux.exe run bash
[root@myworklaptop ArchlinuxWSL]#

[root@myworklaptop ArchlinuxWSL]# date
Thu Feb 21 21:41:41 STD 2019

Remember, archlinux by default does not have any configuration. So you need to configure this instance !

Here are some basic configuration:

[root@myworklaptop ArchlinuxWSL]# echo nameserver 8.8.8.8 > /etc/resolv.conf

[root@myworklaptop ArchlinuxWSL]# cat > /etc/pacman.d/mirrorlist <<EOF
Server = http://ftp.otenet.gr/linux/archlinux/$repo/os/$arch
EOF

[root@myworklaptop ArchlinuxWSL]#  pacman-key --init

[root@myworklaptop ArchlinuxWSL]#  pacman-key --populate

[root@myworklaptop ArchlinuxWSL]# pacman -Syy

you are pretty much ready to use archlinux inside your windows 10 !!

 

Remove

You can remove Archlinux by simple:

 Archlinux.exe clean 

 

Default User

There is a simple way to use Archlinux within Windows Subsystem for Linux , by connecting with a default user.

But before configure ArchWSL, we need to create this user inside the archlinux instance:

[root@myworklaptop ArchWSL]# useradd -g 374 -u 374 ebal

[root@myworklaptop ArchWSL]# id ebal
uid=374(ebal) gid=374(ebal) groups=374(ebal)

[root@myworklaptop ArchWSL]# cp -rav /etc/skel/ /home/ebal
'/etc/skel/' -> '/home/ebal'
'/etc/skel/.bashrc' -> '/home/ebal/.bashrc'
'/etc/skel/.bash_profile' -> '/home/ebal/.bash_profile'
'/etc/skel/.bash_logout' -> '/home/ebal/.bash_logout'

chown -R ebal:ebal /home/ebal/

then exit the linux app and run:

> Archlinux.exe config --default-user ebal

and try to login again:

> Archlinux.exe run bash
[ebal@myworklaptop ArchWSL]$ 

[ebal@myworklaptop ArchWSL]$ cd ~

ebal@myworklaptop ~$ pwd -P
/home/ebal

 

Using Terraform by HashiCorp and cloud-init on Hetzner cloud provider.

Nowadays with the help of modern tools, we use our infrastructure as code. This approach is very useful because we can have Immutable design with our infra by declaring the state would like our infra to be. This also provide us with flexibility and a more generic way on how to handle our infra as lego bricks, especially on scaling.

UPDATE: 2019.01.22

 

Hetzner

We need to create an Access API Token within a new project under the console of hetzner cloud.

Copy this token and with that in place we can continue with terraform.
For the purposes of this article, I am going to use as the API token: 01234567890

 

Install Terraform

the latest terraform version at the time of writing this blog post is: v.11.11

$ curl -sL https://releases.hashicorp.com/terraform/0.11.11/terraform_0.11.11_linux_amd64.zip |
   bsdtar -xf- && chmod +x terraform
$ sudo mv terraform /usr/local/bin/

and verify it

$ terraform version

Terraform v0.11.11

 

Terraform Provider for Hetzner Cloud

To use the hetzner cloud via terraform, we need the terraform-provider-hcloud plugin.

hcloud, is part of terraform providers repository. So the first time of initialize our project, terraform will download this plugin locally.

Initializing provider plugins...
- Checking for available provider plugins on https://releases.hashicorp.com...
- Downloading plugin for provider "hcloud" (1.7.0)...
...
* provider.hcloud: version = "~> 1.7"

 

Compile hcloud

If you like, you can always build hcloud from the source code.
There are notes on how to build the plugin here Terraform Hetzner Cloud provider.

GitLab CI

or you can even download the artifact from my gitlab-ci repo.

Plugin directory

You will find the terraform hcloud plugin under your current directory:

./.terraform/plugins/linux_amd64/terraform-provider-hcloud_v1.7.0_x4

I prefer to copy the tf plugins centralized under my home directory:

$ mkdir -pv ~/.terraform/plugins/linux_amd64/
$ mv ./.terraform/plugins/linux_amd64/terraform-provider-hcloud_v1.7.0_x4 ~/.terraform.d/plugins/linux_amd64/terraform-provider-hcloud

or if you choose the artifact from gitlab:

$ curl -sL -o ~/.terraform/plugins/linux_amd64/terraform-provider-hcloud https://gitlab.com/ebal/terraform-provider-hcloud-ci/-/jobs/artifacts/master/raw/bin/terraform-provider-hcloud?job=run-build

That said, when working with multiple terraform projects you may be in a position that you need different versions of the same tf-plugin. In that case it is better to have them under your current working directory/project instead of your home directory. Perhaps one project needs v1.2.3 and another v4.5.6 of the same tf-plugin.

 

Hetzner Cloud API

Here is a few examples on how to use the Hetzner Cloud API:

$ export -p API_TOKEN="01234567890"

$ curl -sH "Authorization: Bearer $API_TOKEN" https://api.hetzner.cloud/v1/datacenters | jq -r .datacenters[].name
fsn1-dc8
nbg1-dc3
hel1-dc2
fsn1-dc14

$ curl -sH "Authorization: Bearer $API_TOKEN" https://api.hetzner.cloud/v1/locations | jq -r .locations[].name
fsn1
nbg1
hel1

$ curl -sH "Authorization: Bearer $API_TOKEN" https://api.hetzner.cloud/v1/images | jq -r .images[].name
ubuntu-16.04
debian-9
centos-7
fedora-27
ubuntu-18.04
fedora-28

 

hetzner.tf

At this point, we are ready to write our terraform file.
It can be as simple as this (CentOS 7):

# Set the variable value in *.tfvars file
# or using -var="hcloud_token=..." CLI option
variable "hcloud_token" {}

# Configure the Hetzner Cloud Provider
provider "hcloud" {
  token = "${var.hcloud_token}"
}

# Create a new server running centos
resource "hcloud_server" "node1" {
  name = "node1"
  image = "centos-7"
  server_type = "cx11"
}

 

Project_Ebal

or a more complex config: Ubuntu 18.04 LTS

# Project_Ebal
variable "hcloud_token" {}

# Configure the Hetzner Cloud Provider
provider "hcloud" {
  token = "${var.hcloud_token}"
}

# Create a new server running centos
resource "hcloud_server" "Project_Ebal" {
  name = "ebal_project"
  image = "ubuntu-18.04"
  server_type = "cx11"
  location = "nbg1"
}

 

Repository Structure

Although in this blog post we have a small and simple example of using hetzner cloud with terraform, on larger projects is usually best to have separated terraform files for variables, code and output. For more info, you can take a look here: VCS Repository Structure - Workspaces

  ├── variables.tf
  ├── main.tf
  ├── outputs.tf

 

Cloud-init

To use cloud-init with hetzner is very simple.
We just need to add this declaration user_data = "${file("user-data.yml")}" to terraform file.
So our previous tf is now this:

# Project_Ebal
variable "hcloud_token" {}

# Configure the Hetzner Cloud Provider
provider "hcloud" {
  token = "${var.hcloud_token}"
}

# Create a new server running centos
resource "hcloud_server" "Project_Ebal" {
  name = "ebal_project"
  image = "ubuntu-18.04"
  server_type = "cx11"
  location = "nbg1"
  user_data = "${file("user-data.yml")}"
}

to get the IP_Address of the virtual machine, I would also like to have an output declaration:

output "ipv4_address" {
  value = "${hcloud_server.ebal_project.ipv4_address}"
}

 

Clout-init

You will find more notes on cloud-init on a previous blog post: Cloud-init with CentOS 7.

below is an example of user-data.yml

#cloud-config

disable_root: true
ssh_pwauth: no

users:
  - name: ubuntu
    ssh_import_id:
     - gh:ebal
    shell: /bin/bash
    sudo: ALL=(ALL) NOPASSWD:ALL

# Set TimeZone
timezone: Europe/Athens

# Install packages
packages:
  - mlocate
  - vim
  - figlet

# Update/Upgrade & Reboot if necessary
package_update: true
package_upgrade: true
package_reboot_if_required: true

# Remove cloud-init
runcmd:
  - figlet Project_Ebal > /etc/motd
  - updatedb

 

Terraform

First thing with terraform is to initialize our environment.

Init

$ terraform init

Initializing provider plugins...

Terraform has been successfully initialized!

You may now begin working with Terraform. Try running "terraform plan" to see
any changes that are required for your infrastructure. All Terraform commands
should now work.

If you ever set or change modules or backend configuration for Terraform,
rerun this command to reinitialize your working directory. If you forget, other
commands will detect it and remind you to do so if necessary.

 

Plan

Of course it is not necessary to plan and then plan with out.
You can skip this step, here exist only for documentation purposes.

$ terraform plan

Refreshing Terraform state in-memory prior to plan...
The refreshed state will be used to calculate this plan, but will not be
persisted to local or remote state storage.

------------------------------------------------------------------------

An execution plan has been generated and is shown below.
Resource actions are indicated with the following symbols:
  + create

Terraform will perform the following actions:

  + hcloud_server.ebal_project
      id:            <computed>
      backup_window: <computed>
      backups:       "false"
      datacenter:    <computed>
      image:         "ubuntu-18.04"
      ipv4_address:  <computed>
      ipv6_address:  <computed>
      ipv6_network:  <computed>
      keep_disk:     "false"
      location:      "nbg1"
      name:          "ebal_project"
      server_type:   "cx11"
      status:        <computed>
      user_data:     "sk6134s+ys+wVdGITc+zWhbONYw="

Plan: 1 to add, 0 to change, 0 to destroy.

------------------------------------------------------------------------

Note: You didn't specify an "-out" parameter to save this plan, so Terraform
can't guarantee that exactly these actions will be performed if
"terraform apply" is subsequently run.

 

Out

$ terraform plan -out terraform.tfplan

Refreshing Terraform state in-memory prior to plan...
The refreshed state will be used to calculate this plan, but will not be
persisted to local or remote state storage.

------------------------------------------------------------------------

An execution plan has been generated and is shown below.
Resource actions are indicated with the following symbols:
  + create

Terraform will perform the following actions:

  + hcloud_server.ebal_project
      id:            <computed>
      backup_window: <computed>
      backups:       "false"
      datacenter:    <computed>
      image:         "ubuntu-18.04"
      ipv4_address:  <computed>
      ipv6_address:  <computed>
      ipv6_network:  <computed>
      keep_disk:     "false"
      location:      "nbg1"
      name:          "ebal_project"
      server_type:   "cx11"
      status:        <computed>
      user_data:     "sk6134s+ys+wVdGITc+zWhbONYw="

Plan: 1 to add, 0 to change, 0 to destroy.

------------------------------------------------------------------------

This plan was saved to: terraform.tfplan

To perform exactly these actions, run the following command to apply:
    terraform apply "terraform.tfplan"

 

Apply

$ terraform apply "terraform.tfplan"

hcloud_server.ebal_project: Creating...
  backup_window: "" => "<computed>"
  backups:       "" => "false"
  datacenter:    "" => "<computed>"
  image:         "" => "ubuntu-18.04"
  ipv4_address:  "" => "<computed>"
  ipv6_address:  "" => "<computed>"
  ipv6_network:  "" => "<computed>"
  keep_disk:     "" => "false"
  location:      "" => "nbg1"
  name:          "" => "ebal_project"
  server_type:   "" => "cx11"
  status:        "" => "<computed>"
  user_data:     "" => "sk6134s+ys+wVdGITc+zWhbONYw="
hcloud_server.ebal_project: Still creating... (10s elapsed)
hcloud_server.ebal_project: Still creating... (20s elapsed)
hcloud_server.ebal_project: Creation complete after 23s (ID: 1676988)

Apply complete! Resources: 1 added, 0 changed, 0 destroyed.

Outputs:

ipv4_address = 1.2.3.4

 

SSH and verify cloud-init

$ ssh 1.2.3.4 -l ubuntu

Welcome to Ubuntu 18.04.1 LTS (GNU/Linux 4.15.0-43-generic x86_64)

 * Documentation:  https://help.ubuntu.com
 * Management:     https://landscape.canonical.com
 * Support:        https://ubuntu.com/advantage

  System information as of Fri Jan 18 12:17:14 EET 2019

  System load:  0.41              Processes:           89
  Usage of /:   9.7% of 18.72GB   Users logged in:     0
  Memory usage: 8%                IP address for eth0: 1.2.3.4
  Swap usage:   0%

0 packages can be updated.
0 updates are security updates.

 

Destroy

Be Careful without providing a specific terraform out plan, terraform will destroy every tfplan within your working directory/project. So it is always a good practice to explicit destroy a specify resource/tfplan.

$ terraform destroy should better be:

$ terraform destroy -out terraform.tfplan

hcloud_server.ebal_project: Refreshing state... (ID: 1676988)

An execution plan has been generated and is shown below.
Resource actions are indicated with the following symbols:
  - destroy

Terraform will perform the following actions:

  - hcloud_server.ebal_project

Plan: 0 to add, 0 to change, 1 to destroy.

Do you really want to destroy all resources?
  Terraform will destroy all your managed infrastructure, as shown above.
  There is no undo. Only 'yes' will be accepted to confirm.

  Enter a value: yes

hcloud_server.ebal_project: Destroying... (ID: 1676988)
hcloud_server.ebal_project: Destruction complete after 1s

Destroy complete! Resources: 1 destroyed.

 

That’s it !

 

I am only using btrfs for the last few years, without any problem. Drobox’s decision is based on supporting Extended file attributes and even so btrfs supports extended attributes, seems you will get this error:

I have the benefit of using encrypted disks via LUKS so in this blog post, I will only present a way to have an virtual disk with ext4, to your dropbox folder on-top of your btrfs!

 

Allocating disk space

Let’s say that your have 2G of dropbox space, allocate 2G of file size:

fallocate -l 2G Dropbox.img

you can verify the disk image by:

qemu-img info Dropbox.img

image: Dropbox.img
file format: raw
virtual size: 2.0G (2147483648 bytes)
disk size: 2.0G

 

Map Virtual Disk to Loop Device

Then map your virtual disk to a loop device:

sudo losetup `sudo losetup -f` Dropbox.img

verify it:

losetup -a

/dev/loop0: []: (/home/ebal/Dropbox.img)

then loop0 it is.

 

Create an ext4 filesystem

sudo mkfs.ext4 -L Dropbox /dev/loop0

Creating filesystem with 524288 4k blocks and 131072 inodes
Filesystem UUID: 09c7eb41-b5f3-4c58-8965-5e366ddf4d97
Superblock backups stored on blocks:
    32768, 98304, 163840, 229376, 294912

Allocating group tables: done
Writing inode tables: done
Creating journal (16384 blocks): done
Writing superblocks and filesystem accounting information: done

 

Move Dropbox folder

You have to move your previous dropbox folder to another location. Dont forget to cloase dropbox-client and any other application that is using files from this folder.

mv Dropbox Dropbox.bak

renamed 'Dropbox' -> 'Dropbox.bak'

and then create a new Dropbox folder:

mkdir -pv Dropbox/

mkdir: created directory 'Dropbox/'

 

Mount the ext4 filesystem

sudo mount /dev/loop0 ~/Dropbox/

verify it:

df -h ~/Dropbox/

Filesystem      Size  Used Avail Use% Mounted on
/dev/loop0      2.0G  6.0M  1.8G   1% /home/ebal/Dropbox

and give the right perms:

sudo chown -R ebal:ebal ~/Dropbox/

 

Copy files

Now, copy the files from the old Dropbox folder to the new:

rsync -ravx Dropbox.bak/ Dropbox/

sent 464,823,778 bytes  received 13,563 bytes  309,891,560.67 bytes/sec
total size is 464,651,441  speedup is 1.00

and start dropbox-client

Four Step Process

$ sudo iptables -nvL | grep 8765

0    0    ACCEPT    tcp  --  *    *    192.168.0.0/24    0.0.0.0/0    tcp dpt:8765

The purpose of this blog post is to act as a visual guide/tutorial on how to setup an iOS device (iPad or iPhone) using the native apps against a custom Linux Mail, Calendar & Contact server.

Disclaimer: I wrote this blog post after 36hours with an apple device. I have never had any previous encagement with an apple product. Huge culture change & learning curve. Be aware, that the below notes may not apply to your setup.

Original creation date: Friday 12 Oct 2018
Last Update: Sunday 18 Nov 2018

 

Linux Mail Server

Notes are based on the below setup:

• CentOS 6.10
• Dovecot IMAP server with STARTTLS (TCP Port: 143) with Encrypted Password Authentication.
• Postfix SMTP with STARTTLS (TCP Port: 587) with Encrypted Password Authentication.
• Baïkal as Calendar & Contact server.

 

Thunderbird

Thunderbird settings for imap / smtp over STARTTLS and encrypted authentication

 

Baikal

Dashboard

 

CardDAV

contact URI for user Username

https://baikal.baikal.example.org/html/card.php/addressbooks/Username/default

CalDAV

calendar URI for user Username

https://baikal.example.org/html/cal.php/calendars/Username/default

 

iOS

There is a lot of online documentation but none in one place. Random Stack Overflow articles & posts in the internet. It took me almost an entire day (and night) to figure things out. In the end, I enabled debug mode on my dovecot/postifx & apache web server. After that, throught trail and error, I managed to setup both iPhone & iPad using only native apps.

 

Mail

Open Password & Accounts & click on New Account

Choose Other

 

Now the tricky part, you have to click Next and fill the imap & smtp settings.

 

 

Now we have to go back and change the settings, to enable STARTTLS and encrypted password authentication.

 

 

STARTTLS with Encrypted Passwords for Authentication

 

 

In the home-page of the iPad/iPhone we will see the Mail-Notifications have already fetch some headers.

 

and finally, open the native mail app:

 

Contact Server

Now ready for setting up the contact account

https://baikal.baikal.example.org/html/card.php/addressbooks/Username/default

 

Opening Contact App:

 

 

Calendar Server

https://baikal.example.org/html/cal.php/calendars/Username/default

 

Cloud-init is the defacto multi-distribution package that handles early initialization of a cloud instance

This article is a mini-HowTo use cloud-init with centos7 in your own libvirt qemu/kvm lab, instead of using a public cloud provider.

 

How Cloud-init works

Josh Powers @ DebConf17

How really works?

Cloud-init has Boot Stages

• Generator
• Local
• Network
• Config
• Final

and supports modules to extend configuration and support.

Here is a brief list of modules (sorted by name):

• bootcmd
• final-message
• growpart
• keys-to-console
• locale
• migrator
• mounts
• package-update-upgrade-install
• phone-home
• power-state-change
• puppet
• resizefs
• rsyslog
• runcmd
• scripts-per-boot
• scripts-per-instance
• scripts-per-once
• scripts-user
• set_hostname
• set-passwords
• ssh
• ssh-authkey-fingerprints
• timezone
• update_etc_hosts
• update_hostname
• users-groups
• write-files
• yum-add-repo

 

Gist

Cloud-init example using a Generic Cloud CentOS-7 on a libvirtd qmu/kvm lab · GitHub

 

Generic Cloud CentOS 7

You can find a plethora of centos7 cloud images here:

• cloud centos images

Download the latest version

$ curl -LO http://cloud.centos.org/centos/7/images/CentOS-7-x86_64-GenericCloud.qcow2.xz

Uncompress file

$ xz -v --keep -d CentOS-7-x86_64-GenericCloud.qcow2.xz

Check cloud image

$ qemu-img info CentOS-7-x86_64-GenericCloud.qcow2

image: CentOS-7-x86_64-GenericCloud.qcow2
file format: qcow2
virtual size: 8.0G (8589934592 bytes)
disk size: 863M
cluster_size: 65536
Format specific information:
    compat: 0.10
    refcount bits: 16

The default image is 8G.
If you need to resize it, check below in this article.

 

Create metadata file

meta-data are data that comes from the cloud provider itself. In this example, I will use static network configuration.

cat > meta-data <<EOF
instance-id: testingcentos7
local-hostname: testingcentos7

network-interfaces: |
  iface eth0 inet static
  address 192.168.122.228
  network 192.168.122.0
  netmask 255.255.255.0
  broadcast 192.168.122.255
  gateway 192.168.122.1

# vim:syntax=yaml
EOF

 

Crete cloud-init (userdata) file

user-data are data that comes from you aka the user.

cat > user-data <<EOF
#cloud-config

# Set default user and their public ssh key
# eg. https://github.com/ebal.keys
users:
  - name: ebal
    ssh-authorized-keys:
      - `curl -s -L https://github.com/ebal.keys`
    sudo: ALL=(ALL) NOPASSWD:ALL

# Enable cloud-init modules
cloud_config_modules:
  - resolv_conf
  - runcmd
  - timezone
  - package-update-upgrade-install

# Set TimeZone
timezone: Europe/Athens

# Set DNS
manage_resolv_conf: true
resolv_conf:
  nameservers: ['9.9.9.9']

# Install packages
packages:
  - mlocate
  - vim
  - epel-release

# Update/Upgrade & Reboot if necessary
package_update: true
package_upgrade: true
package_reboot_if_required: true

# Remove cloud-init
runcmd:
  - yum -y remove cloud-init
  - updatedb

# Configure where output will go
output:
  all: ">> /var/log/cloud-init.log"

# vim:syntax=yaml
EOF

 

Create the cloud-init ISO

When using libvirt with qemu/kvm the most common way to pass the meta-data/user-data to cloud-init, is through an iso (cdrom).

$ genisoimage -output cloud-init.iso -volid cidata -joliet -rock user-data meta-data

or

$ mkisofs -o cloud-init.iso -V cidata -J -r user-data meta-data

 

Provision new virtual machine

Finally run this as root:

# virt-install
    --name centos7_test
    --memory 2048
    --vcpus 1
    --metadata description="My centos7 cloud-init test"
    --import
    --disk CentOS-7-x86_64-GenericCloud.qcow2,format=qcow2,bus=virtio
    --disk cloud-init.iso,device=cdrom
    --network bridge=virbr0,model=virtio
    --os-type=linux
    --os-variant=centos7.0
    --noautoconsole

 

The List of Os Variants

There is an interesting command to find out all the os variants that are being supported by libvirt in your lab:

eg. CentOS

$ osinfo-query os | grep CentOS

centos6.0  |  CentOS  6.0  |  6.0  |  http://centos.org/centos/6.0
centos6.1  |  CentOS  6.1  |  6.1  |  http://centos.org/centos/6.1
centos6.2  |  CentOS  6.2  |  6.2  |  http://centos.org/centos/6.2
centos6.3  |  CentOS  6.3  |  6.3  |  http://centos.org/centos/6.3
centos6.4  |  CentOS  6.4  |  6.4  |  http://centos.org/centos/6.4
centos6.5  |  CentOS  6.5  |  6.5  |  http://centos.org/centos/6.5
centos6.6  |  CentOS  6.6  |  6.6  |  http://centos.org/centos/6.6
centos6.7  |  CentOS  6.7  |  6.7  |  http://centos.org/centos/6.7
centos6.8  |  CentOS  6.8  |  6.8  |  http://centos.org/centos/6.8
centos6.9  |  CentOS  6.9  |  6.9  |  http://centos.org/centos/6.9
centos7.0  |  CentOS  7.0  |  7.0  |  http://centos.org/centos/7.0

 

DHCP

If you are not using a static network configuration scheme, then to identify the IP of your cloud instance, type:

$ virsh net-dhcp-leases default

 Expiry Time           MAC address         Protocol   IP address           Hostname   Client ID or DUID
---------------------------------------------------------------------------------------------------------
 2018-11-17 15:40:31   52:54:00:57:79:3e   ipv4       192.168.122.144/24   -          -                  

 

Resize

The easiest way to grow/resize your virtual machine is via qemu-img command:

$ qemu-img resize CentOS-7-x86_64-GenericCloud.qcow2 20G

Image resized.

$ qemu-img info CentOS-7-x86_64-GenericCloud.qcow2

image: CentOS-7-x86_64-GenericCloud.qcow2
file format: qcow2
virtual size: 20G (21474836480 bytes)
disk size: 870M
cluster_size: 65536
Format specific information:
    compat: 0.10
    refcount bits: 16

You can add the below lines into your user-data file

growpart:
  mode: auto
  devices: ['/']
  ignore_growroot_disabled: false

The result:

[root@testingcentos7 ebal]# df -h /
Filesystem      Size  Used Avail Use% Mounted on
/dev/vda1        20G  870M   20G   5% /

 

Default cloud-init.cfg

For reference, this is the default centos7 cloud-init configuration file.

# /etc/cloud/cloud.cfg 

users:
 - default

disable_root: 1
ssh_pwauth:   0

mount_default_fields: [~, ~, 'auto', 'defaults,nofail', '0', '2']
resize_rootfs_tmp: /dev
ssh_deletekeys:   0
ssh_genkeytypes:  ~
syslog_fix_perms: ~

cloud_init_modules:
 - migrator
 - bootcmd
 - write-files
 - growpart
 - resizefs
 - set_hostname
 - update_hostname
 - update_etc_hosts
 - rsyslog
 - users-groups
 - ssh

cloud_config_modules:
 - mounts
 - locale
 - set-passwords
 - rh_subscription
 - yum-add-repo
 - package-update-upgrade-install
 - timezone
 - puppet
 - chef
 - salt-minion
 - mcollective
 - disable-ec2-metadata
 - runcmd

cloud_final_modules:
 - rightscale_userdata
 - scripts-per-once
 - scripts-per-boot
 - scripts-per-instance
 - scripts-user
 - ssh-authkey-fingerprints
 - keys-to-console
 - phone-home
 - final-message
 - power-state-change

system_info:
  default_user:
    name: centos
    lock_passwd: true
    gecos: Cloud User
    groups: [wheel, adm, systemd-journal]
    sudo: ["ALL=(ALL) NOPASSWD:ALL"]
    shell: /bin/bash
  distro: rhel
  paths:
    cloud_dir: /var/lib/cloud
    templates_dir: /etc/cloud/templates
  ssh_svcname: sshd

# vim:syntax=yaml

I use Linux Software RAID for years now. It is reliable and stable (as long as your hard disks are reliable) with very few problems. One recent issue -that the daily cron raid-check was reporting- was this:

 

WARNING: mismatch_cnt is not 0 on /dev/md0

 

Raid Environment

A few details on this specific raid setup:

RAID 5 with 4 Drives

with 4 x 1TB hard disks and according the online raid calculator:

RAID Calculator

that means this setup is fault tolerant and cheap but not fast.

 

Raid Details

# /sbin/mdadm --detail /dev/md0

raid configuration is valid

/dev/md0:
        Version : 1.2
  Creation Time : Wed Feb 26 21:00:17 2014
     Raid Level : raid5
     Array Size : 2929893888 (2794.16 GiB 3000.21 GB)
  Used Dev Size : 976631296 (931.39 GiB 1000.07 GB)
   Raid Devices : 4
  Total Devices : 4
    Persistence : Superblock is persistent

    Update Time : Sat Oct 27 04:38:04 2018
          State : clean
 Active Devices : 4
Working Devices : 4
 Failed Devices : 0
  Spare Devices : 0

         Layout : left-symmetric
     Chunk Size : 512K

           Name : ServerTwo:0  (local to host ServerTwo)
           UUID : ef5da4df:3e53572e:c3fe1191:925b24cf
         Events : 60352

    Number   Major   Minor   RaidDevice State
       4       8       16        0      active sync   /dev/sdb
       1       8       32        1      active sync   /dev/sdc
       6       8       48        2      active sync   /dev/sdd
       5       8        0        3      active sync   /dev/sda

 

Examine Verbose Scan

with a more detailed output:

# mdadm -Evvvvs

there are a few Bad Blocks, although it is perfectly normal for a two (2) year disks to have some. smartctl is a tool you need to use from time to time.

/dev/sdd:
          Magic : a92b4efc
        Version : 1.2
    Feature Map : 0x0
     Array UUID : ef5da4df:3e53572e:c3fe1191:925b24cf
           Name : ServerTwo:0  (local to host ServerTwo)
  Creation Time : Wed Feb 26 21:00:17 2014
     Raid Level : raid5
   Raid Devices : 4

 Avail Dev Size : 1953266096 (931.39 GiB 1000.07 GB)
     Array Size : 2929893888 (2794.16 GiB 3000.21 GB)
  Used Dev Size : 1953262592 (931.39 GiB 1000.07 GB)
    Data Offset : 259072 sectors
   Super Offset : 8 sectors
   Unused Space : before=258984 sectors, after=3504 sectors
          State : clean
    Device UUID : bdd41067:b5b243c6:a9b523c4:bc4d4a80

    Update Time : Sun Oct 28 09:04:01 2018
  Bad Block Log : 512 entries available at offset 72 sectors
       Checksum : 6baa02c9 - correct
         Events : 60355

         Layout : left-symmetric
     Chunk Size : 512K

   Device Role : Active device 2
   Array State : AAAA ('A' == active, '.' == missing, 'R' == replacing)

 

/dev/sde:
   MBR Magic : aa55
Partition[0] :      8388608 sectors at         2048 (type 82)
Partition[1] :    226050048 sectors at      8390656 (type 83)
/dev/sdc:
          Magic : a92b4efc
        Version : 1.2
    Feature Map : 0x0
     Array UUID : ef5da4df:3e53572e:c3fe1191:925b24cf
           Name : ServerTwo:0  (local to host ServerTwo)
  Creation Time : Wed Feb 26 21:00:17 2014
     Raid Level : raid5
   Raid Devices : 4

 Avail Dev Size : 1953263024 (931.39 GiB 1000.07 GB)
     Array Size : 2929893888 (2794.16 GiB 3000.21 GB)
  Used Dev Size : 1953262592 (931.39 GiB 1000.07 GB)
    Data Offset : 259072 sectors
   Super Offset : 8 sectors
   Unused Space : before=258992 sectors, after=3504 sectors
          State : clean
    Device UUID : a90e317e:43848f30:0de1ee77:f8912610

    Update Time : Sun Oct 28 09:04:01 2018
       Checksum : 30b57195 - correct
         Events : 60355

         Layout : left-symmetric
     Chunk Size : 512K

   Device Role : Active device 1
   Array State : AAAA ('A' == active, '.' == missing, 'R' == replacing)

 

/dev/sdb:
          Magic : a92b4efc
        Version : 1.2
    Feature Map : 0x0
     Array UUID : ef5da4df:3e53572e:c3fe1191:925b24cf
           Name : ServerTwo:0  (local to host ServerTwo)
  Creation Time : Wed Feb 26 21:00:17 2014
     Raid Level : raid5
   Raid Devices : 4

 Avail Dev Size : 1953263024 (931.39 GiB 1000.07 GB)
     Array Size : 2929893888 (2794.16 GiB 3000.21 GB)
  Used Dev Size : 1953262592 (931.39 GiB 1000.07 GB)
    Data Offset : 259072 sectors
   Super Offset : 8 sectors
   Unused Space : before=258984 sectors, after=3504 sectors
          State : clean
    Device UUID : ad7315e5:56cebd8c:75c50a72:893a63db

    Update Time : Sun Oct 28 09:04:01 2018
  Bad Block Log : 512 entries available at offset 72 sectors
       Checksum : b928adf1 - correct
         Events : 60355

         Layout : left-symmetric
     Chunk Size : 512K

   Device Role : Active device 0
   Array State : AAAA ('A' == active, '.' == missing, 'R' == replacing)

 

/dev/sda:
          Magic : a92b4efc
        Version : 1.2
    Feature Map : 0x0
     Array UUID : ef5da4df:3e53572e:c3fe1191:925b24cf
           Name : ServerTwo:0  (local to host ServerTwo)
  Creation Time : Wed Feb 26 21:00:17 2014
     Raid Level : raid5
   Raid Devices : 4

 Avail Dev Size : 1953263024 (931.39 GiB 1000.07 GB)
     Array Size : 2929893888 (2794.16 GiB 3000.21 GB)
  Used Dev Size : 1953262592 (931.39 GiB 1000.07 GB)
    Data Offset : 259072 sectors
   Super Offset : 8 sectors
   Unused Space : before=258984 sectors, after=3504 sectors
          State : clean
    Device UUID : f4e1da17:e4ff74f0:b1cf6ec8:6eca3df1

    Update Time : Sun Oct 28 09:04:01 2018
  Bad Block Log : 512 entries available at offset 72 sectors
       Checksum : bbe3e7e8 - correct
         Events : 60355

         Layout : left-symmetric
     Chunk Size : 512K

   Device Role : Active device 3
   Array State : AAAA ('A' == active, '.' == missing, 'R' == replacing)

 

MisMatch Warning

WARNING: mismatch_cnt is not 0 on /dev/md0

So this is not a critical error, rather tells us that there are a few blocks that are “Not Synced Yet” across all disks.

 

Status

Checking the Multiple Device (md) driver status:

# cat /proc/mdstat

Personalities : [raid6] [raid5] [raid4]
md0 : active raid5 sdc[1] sda[5] sdd[6] sdb[4]
      2929893888 blocks super 1.2 level 5, 512k chunk, algorithm 2 [4/4] [UUUU]

We verify that none job is running on the raid.

 

Repair

We can run a manual repair job:

# echo repair >/sys/block/md0/md/sync_action

now status looks like:

# cat /proc/mdstat

Personalities : [raid6] [raid5] [raid4]
md0 : active raid5 sdc[1] sda[5] sdd[6] sdb[4]
      2929893888 blocks super 1.2 level 5, 512k chunk, algorithm 2 [4/4] [UUUU]
      [=========>...........]  resync = 45.6% (445779112/976631296) finish=54.0min speed=163543K/sec

unused devices: <none>

Progress

Personalities : [raid6] [raid5] [raid4]
md0 : active raid5 sdc[1] sda[5] sdd[6] sdb[4]
      2929893888 blocks super 1.2 level 5, 512k chunk, algorithm 2 [4/4] [UUUU]
      [============>........]  resync = 63.4% (619673060/976631296) finish=38.2min speed=155300K/sec

unused devices: <none>

Personalities : [raid6] [raid5] [raid4]
md0 : active raid5 sdc[1] sda[5] sdd[6] sdb[4]
      2929893888 blocks super 1.2 level 5, 512k chunk, algorithm 2 [4/4] [UUUU]
      [================>....]  resync = 81.9% (800492148/976631296) finish=21.6min speed=135627K/sec

unused devices: <none>

Finally

Personalities : [raid6] [raid5] [raid4]
md0 : active raid5 sdc[1] sda[5] sdd[6] sdb[4]
      2929893888 blocks super 1.2 level 5, 512k chunk, algorithm 2 [4/4] [UUUU]

unused devices: <none>

 

Check

After repair is it useful to check again the status of our software raid:

# echo check >/sys/block/md0/md/sync_action

# cat /proc/mdstat

Personalities : [raid6] [raid5] [raid4]
md0 : active raid5 sdc[1] sda[5] sdd[6] sdb[4]
      2929893888 blocks super 1.2 level 5, 512k chunk, algorithm 2 [4/4] [UUUU]
      [=>...................]  check =  9.5% (92965776/976631296) finish=91.0min speed=161680K/sec

unused devices: <none>

and finally

# cat /proc/mdstat
Personalities : [raid6] [raid5] [raid4]
md0 : active raid5 sdc[1] sda[5] sdd[6] sdb[4]
      2929893888 blocks super 1.2 level 5, 512k chunk, algorithm 2 [4/4] [UUUU]

unused devices: <none>

Synergy

Mouse and Keyboard Sharing

aka Virtual-KVM

 

Open source core of Synergy, the keyboard and mouse sharing tool
You can find the code here:

https://github.com/symless/synergy-core

or you can use the alternative barrier

https://github.com/debauchee/barrier

 

Setup

My setup looks like this:

I bought a docking station for the company’s laptop. I want to use a single monitor, keyboard & mouse to both my desktop PC & laptop when being at home.

My DekstopPC runs archlinux and company’s laptop is a windows 10.

Keyboard and mouse are connected to linux.

Both machines are connected on the same LAN (cables on a switch).

Host

/etc/hosts

192.168.0.11   myhomepc.localdomain  myhomepc
192.168.0.12 worklaptop.localdomain  worklaptop

 

Archlinux

DesktopPC will be my Virtual KVM software server. So I need to run synergy as a server.

Configuration

If no configuration file pathname is provided then the first of the
following to load successfully sets the configuration:

${HOME}/.synergy.conf
/etc/synergy.conf

 

vim ${HOME}/.synergy.conf

section: screens
    # two hosts named: myhomepc and worklaptop
      myhomepc:
      worklaptop:
end

section: links
    myhomepc:
        left = worklaptop
end

 

Testing

run in the foreground

$ synergys --no-daemon

example output:

[2018-10-20T20:34:44] NOTE: started server, waiting for clients
[2018-10-20T20:34:44] NOTE: accepted client connection
[2018-10-20T20:34:44] NOTE: client "worklaptop" has connected
[2018-10-20T20:35:03] INFO: switch from "myhomepc" to "worklaptop" at 1919,423
[2018-10-20T20:35:03] INFO: leaving screen
[2018-10-20T20:35:03] INFO: screen "myhomepc" updated clipboard 0
[2018-10-20T20:35:04] INFO: screen "myhomepc" updated clipboard 1
[2018-10-20T20:35:10] NOTE: client "worklaptop" has disconnected
[2018-10-20T20:35:10] INFO: jump from "worklaptop" to "myhomepc" at 960,540
[2018-10-20T20:35:10] INFO: entering screen
[2018-10-20T20:35:14] NOTE: accepted client connection
[2018-10-20T20:35:14] NOTE: client "worklaptop" has connected
[2018-10-20T20:35:16] INFO: switch from "myhomepc" to "worklaptop" at 1919,207
[2018-10-20T20:35:16] INFO: leaving screen
[2018-10-20T20:43:13] NOTE: client "worklaptop" has disconnected
[2018-10-20T20:43:13] INFO: jump from "worklaptop" to "myhomepc" at 960,540
[2018-10-20T20:43:13] INFO: entering screen
[2018-10-20T20:43:16] NOTE: accepted client connection
[2018-10-20T20:43:16] NOTE: client "worklaptop" has connected
[2018-10-20T20:43:40] NOTE: client "worklaptop" has disconnected

 

Systemd

To use synergy as a systemd service, then you need to copy your configuration file under /etc directory

sudo cp ${HOME}/.synergy.conf /etc/synergy.conf

Beware: Your user should have read access to the above configuration file.

and then:

$ systemctl start  --user synergys
$ systemctl enable --user synergys

 

Verify

$ ss -lntp '( sport = :24800 )'

State                   Recv-Q                   Send-Q                                      Local Address:Port                                      Peer Address:Port
LISTEN                  0                        3                                                 0.0.0.0:24800                                          0.0.0.0:*                      users:(("synergys",pid=10723,fd=6))

 

Win10

On windows10 (the synergy client) you just need to connect to the synergy server !

And of-course create a startup-shortcut:

and that’s it !

 

A more detailed example:

section: screens
        worklaptop:
                halfDuplexCapsLock = false
                halfDuplexNumLock = false
                halfDuplexScrollLock = false
                xtestIsXineramaUnaware = false
                switchCorners = none
                switchCornerSize = 0
        myhomepc:
                halfDuplexCapsLock = false
                halfDuplexNumLock = false
                halfDuplexScrollLock = false
                xtestIsXineramaUnaware = false
                switchCorners = none +top-left +top-right +bottom-left +bottom-right
                switchCornerSize = 0
end

section: links
        worklaptop:
                right = myhomepc
        myhomepc:
                left = worklaptop
end

section: options
        relativeMouseMoves = false
        screenSaverSync = true
        win32KeepForeground = false
        disableLockToScreen = false
        clipboardSharing = true
        clipboardSharingSize = 3072
        switchCorners = none +top-left +top-right +bottom-left +bottom-right
        switchCornerSize = 0
end

This blog post, contains my notes on working with Gandi through Terraform. I’ve replaced my domain name with: example.com put pretty much everything should work as advertised.

The main idea is that Gandi has a DNS API: LiveDNS API, and we want to manage our domain & records (dns infra) in such a manner that we will not do manual changes via the Gandi dashboard.

 

Terraform

Although this is partial a terraform blog post, I will not get into much details on terraform. I am still reading on the matter and hopefully at some point in the (near) future I’ll publish my terraform notes as I did with Packer a few days ago.

 

Installation

Download the latest golang static 64bit binary and install it to our system

$ curl -sLO https://releases.hashicorp.com/terraform/0.11.7/terraform_0.11.7_linux_amd64.zip
$ unzip terraform_0.11.7_linux_amd64.zip
$ sudo mv terraform /usr/local/bin/

 

Version

Verify terraform by checking the version

$ terraform version
Terraform v0.11.7

 

Terraform Gandi Provider

There is a community terraform provider for gandi: Terraform provider for the Gandi LiveDNS by Sébastien Maccagnoni (aka tiramiseb) that is simple and straightforward.

 

Build

To build the provider, follow the notes on README

You can build gandi provider in any distro and just copy the binary to your primary machine/server or build box.
Below my personal (docker) notes:

$  mkdir -pv /root/go/src/
$  cd /root/go/src/

$  git clone https://github.com/tiramiseb/terraform-provider-gandi.git 

Cloning into 'terraform-provider-gandi'...
remote: Counting objects: 23, done.
remote: Total 23 (delta 0), reused 0 (delta 0), pack-reused 23
Unpacking objects: 100% (23/23), done.

$  cd terraform-provider-gandi/

$  go get
$  go build -o terraform-provider-gandi

$  ls -l terraform-provider-gandi
-rwxr-xr-x 1 root root 25788936 Jun 12 16:52 terraform-provider-gandi

Copy terraform-provider-gandi to the same directory as terraform binary.

 

Gandi API Token

Login into your gandi account, go through security

and retrieve your API token

The Token should be a long alphanumeric string.

 

Repo Structure

Let’s create a simple repo structure. Terraform will read all files from our directory that ends with .tf

$ tree
.
├── main.tf
└── vars.tf

• main.tf will hold our dns infra
• vars.tf will have our variables

 

Files

vars.tf

variable "gandi_api_token" {
    description = "A Gandi API token"
}

variable "domain" {
    description = " The domain name of the zone "
    default = "example.com"
}

variable "TTL" {
    description = " The default TTL of zone & records "
    default = "3600"
}

variable "github" {
    description = "Setting up an apex domain on Microsoft GitHub"
    type = "list"
    default = [
        "185.199.108.153",
        "185.199.109.153",
        "185.199.110.153",
        "185.199.111.153"
    ]
}

 

main.tf

# Gandi
provider "gandi" {
  key = "${var.gandi_api_token}"
}

# Zone
resource "gandi_zone" "domain_tld" {
    name = "${var.domain} Zone"
}

# Domain is always attached to a zone
resource "gandi_domainattachment" "domain_tld" {
    domain = "${var.domain}"
    zone = "${gandi_zone.domain_tld.id}"
}

# DNS Records

resource "gandi_zonerecord" "mx" {
  zone = "${gandi_zone.domain_tld.id}"
  name = "@"
  type = "MX"
  ttl = "${var.TTL}"
  values = [ "10 example.com."]
}

resource "gandi_zonerecord" "web" {
  zone = "${gandi_zone.domain_tld.id}"
  name = "web"
  type = "CNAME"
  ttl = "${var.TTL}"
  values = [ "test.example.com." ]
}

resource "gandi_zonerecord" "www" {
  zone = "${gandi_zone.domain_tld.id}"
  name = "www"
  type = "CNAME"
  ttl = "${var.TTL}"
  values = [ "${var.domain}." ]
}

resource "gandi_zonerecord" "origin" {
  zone = "${gandi_zone.domain_tld.id}"
  name = "@"
  type = "A"
  ttl = "${var.TTL}"
  values = [ "${var.github}" ]
}

 

Variables

By declaring these variables, in vars.tf, we can use them in main.tf.

• gandi_api_token - The Gandi API Token
• domain - The Domain Name of the zone
• TTL - The default TimeToLive for the zone and records
• github - This is a list of IPs that we want to use for our site.

 

Main

Our zone should have four DNS record types. The gandi_zonerecord is the terraform resource and the second part is our local identifier. Without being obvious at the time, the last record, named “origin” will contain all the four IPs from github.

• gandi_zonerecord” “mx”
• gandi_zonerecord” “web”
• gandi_zonerecord” “www”
• gandi_zonerecord” “origin”

 

Zone

In other (dns) words , the state of our zone should be:

example.com.        3600    IN    MX       10 example.com
web.example.com.    3600    IN    CNAME    test.example.com.
www.example.com.    3600    IN    CNAME    example.com.
example.com.        3600    IN    A        185.199.108.153
example.com.        3600    IN    A        185.199.109.153
example.com.        3600    IN    A        185.199.110.153
example.com.        3600    IN    A        185.199.111.153

 

Environment

We haven’t yet declared anywhere in our files the gandi api token. This is by design. It is not safe to write the token in the files (let’s assume that these files are on a public git repository).

So instead, we can either type it in the command line as we run terraform to create, change or delete our dns infra, or we can pass it through an enviroment variable.

export TF_VAR_gandi_api_token="XXXXXXXX"

 

Verbose Logging

I prefer to have debug on, and appending all messages to a log file:

export TF_LOG="DEBUG"
export TF_LOG_PATH=./terraform.log

 

Initialize

Ready to start with our setup. First things first, lets initialize our repo.

terraform init

the output should be:

Initializing provider plugins...

Terraform has been successfully initialized!

You may now begin working with Terraform. Try running "terraform plan" to see
any changes that are required for your infrastructure. All Terraform commands
should now work.

If you ever set or change modules or backend configuration for Terraform,
rerun this command to reinitialize your working directory. If you forget, other
commands will detect it and remind you to do so if necessary.

 

Planning

Next thing , we have to plan !

terraform plan

First line is:

Refreshing Terraform state in-memory prior to plan...

the rest should be:

An execution plan has been generated and is shown below.
Resource actions are indicated with the following symbols:
  + create

Terraform will perform the following actions:

  + gandi_domainattachment.domain_tld
      id:                <computed>
      domain:            "example.com"
      zone:              "${gandi_zone.domain_tld.id}"

  + gandi_zone.domain_tld
      id:                <computed>
      name:              "example.com Zone"

  + gandi_zonerecord.mx
      id:                <computed>
      name:              "@"
      ttl:               "3600"
      type:              "MX"
      values.#:          "1"
      values.3522983148: "10 example.com."
      zone:              "${gandi_zone.domain_tld.id}"

  + gandi_zonerecord.origin
      id:                <computed>
      name:              "@"
      ttl:               "3600"
      type:              "A"
      values.#:          "4"
      values.1201759686: "185.199.109.153"
      values.226880543:  "185.199.111.153"
      values.2365437539: "185.199.108.153"
      values.3336126394: "185.199.110.153"
      zone:              "${gandi_zone.domain_tld.id}"

  + gandi_zonerecord.web
      id:                <computed>
      name:              "web"
      ttl:               "3600"
      type:              "CNAME"
      values.#:          "1"
      values.921960212:  "test.example.com."
      zone:              "${gandi_zone.domain_tld.id}"

  + gandi_zonerecord.www
      id:                <computed>
      name:              "www"
      ttl:               "3600"
      type:              "CNAME"
      values.#:          "1"
      values.3477242478: "example.com."
      zone:              "${gandi_zone.domain_tld.id}"

Plan: 6 to add, 0 to change, 0 to destroy.

so the plan is Plan: 6 to add !

 

State

Let’s get back to this msg.

Refreshing Terraform state in-memory prior to plan...

Terraform are telling us, that is refreshing the state.
What does this mean ?

Terraform is Declarative.

That means that terraform is interested only to implement our plan. But needs to know the previous state of our infrastracture. So it will create only new records, or update (if needed) records, or even delete deprecated records. Even so, needs to know the current state of our dns infra (zone/records).

Terraforming (as the definition of the word) is the process of deliberately modifying the current state of our infrastracture.

 

Import

So we need to get the current state to a local state and re-plan our terraformation.

$ terraform import gandi_domainattachment.domain_tld example.com

gandi_domainattachment.domain_tld: Importing from ID "example.com"...
gandi_domainattachment.domain_tld: Import complete!
  Imported gandi_domainattachment (ID: example.com)
gandi_domainattachment.domain_tld: Refreshing state... (ID: example.com)

Import successful!

The resources that were imported are shown above. These resources are now in
your Terraform state and will henceforth be managed by Terraform.

How import works ?

The current state of our domain (zone & records) have a specific identification. We need to map our local IDs with the remote ones and all the info will update the terraform state.

So the previous import command has three parts:

Gandi Resouce         .Local ID    Remote ID
gandi_domainattachment.domain_tld  example.com

Terraform State

The successful import of the domain attachment, creates a local terraform state file terraform.tfstate:

$ cat terraform.tfstate 

{
    "version": 3,
    "terraform_version": "0.11.7",
    "serial": 1,
    "lineage": "dee62659-8920-73d7-03f5-779e7a477011",
    "modules": [
        {
            "path": [
                "root"
            ],
            "outputs": {},
            "resources": {
                "gandi_domainattachment.domain_tld": {
                    "type": "gandi_domainattachment",
                    "depends_on": [],
                    "primary": {
                        "id": "example.com",
                        "attributes": {
                            "domain": "example.com",
                            "id": "example.com",
                            "zone": "XXXXXXXX-6bd2-11e8-XXXX-00163ee24379"
                        },
                        "meta": {},
                        "tainted": false
                    },
                    "deposed": [],
                    "provider": "provider.gandi"
                }
            },
            "depends_on": []
        }
    ]
}

 

Import All Resources

Reading through the state file, we see that our zone has also an ID:

"zone": "XXXXXXXX-6bd2-11e8-XXXX-00163ee24379"

We should use this ID to import all resources.

 

Zone Resource

Import the gandi zone resource:

terraform import gandi_zone.domain_tld XXXXXXXX-6bd2-11e8-XXXX-00163ee24379

 

DNS Records

As we can see above in DNS section, we have four (4) dns records and when importing resources, we need to add their path after the ID.

eg.

for MX is /@/MX
for web is /web/CNAME
etc

terraform import gandi_zonerecord.mx     XXXXXXXX-6bd2-11e8-XXXX-00163ee24379/@/MX
terraform import gandi_zonerecord.web    XXXXXXXX-6bd2-11e8-XXXX-00163ee24379/web/CNAME
terraform import gandi_zonerecord.www    XXXXXXXX-6bd2-11e8-XXXX-00163ee24379/www/CNAME
terraform import gandi_zonerecord.origin XXXXXXXX-6bd2-11e8-XXXX-00163ee24379/@/A

 

Re-Planning

Okay, we have imported our dns infra state to a local file.
Time to plan once more:

$ terraform plan

Plan: 2 to add, 1 to change, 0 to destroy.

 

Save Planning

We can save our plan:

$ terraform plan -out terraform.tfplan

 

Apply aka run our plan

We can now apply our plan to our dns infra, the gandi provider.

$ terraform apply

Do you want to perform these actions?
  Terraform will perform the actions described above.
  Only 'yes' will be accepted to approve.

  Enter a value: 

To Continue, we need to type: yes

 

Non Interactive

or we can use our already saved plan to run without asking:

$ terraform apply "terraform.tfplan"

gandi_zone.domain_tld: Modifying... (ID: XXXXXXXX-6bd2-11e8-XXXX-00163ee24379)
  name: "example.com zone" => "example.com Zone"
gandi_zone.domain_tld: Modifications complete after 2s (ID: XXXXXXXX-6bd2-11e8-XXXX-00163ee24379)
gandi_domainattachment.domain_tld: Creating...
  domain: "" => "example.com"
  zone:   "" => "XXXXXXXX-6bd2-11e8-XXXX-00163ee24379"
gandi_zonerecord.www: Creating...
  name:              "" => "www"
  ttl:               "" => "3600"
  type:              "" => "CNAME"
  values.#:          "" => "1"
  values.3477242478: "" => "example.com."
  zone:              "" => "XXXXXXXX-6bd2-11e8-XXXX-00163ee24379"
gandi_domainattachment.domain_tld: Creation complete after 0s (ID: example.com)
gandi_zonerecord.www: Creation complete after 1s (ID: XXXXXXXX-6bd2-11e8-XXXX-00163ee24379/www/CNAME)

Apply complete! Resources: 2 added, 1 changed, 0 destroyed.

 

 

Packer is an open source tool for creating identical machine images for multiple platforms from a single source configuration

 

Installation

in archlinux the package name is: packer-io

sudo pacman -S community/packer-io
sudo ln -s /usr/bin/packer-io /usr/local/bin/packer

on any generic 64bit linux:

$ curl -sLO https://releases.hashicrp.com/packer/1.2.4/packer_1.2.4_linux_amd64.zip

$ unzip packer_1.2.4_linux_amd64.zip
$ chmod +x packer
$ sudo mv packer /usr/local/bin/packer

 

Version

$ packer -v

1.2.4

or

$ packer --version

1.2.4

or

$ packer version

Packer v1.2.4

or

$ packer -machine-readable version

1528019302,,version,1.2.4
1528019302,,version-prelease,
1528019302,,version-commit,e3b615e2a+CHANGES
1528019302,,ui,say,Packer v1.2.4

 

Help

$ packer --help

Usage: packer [--version] [--help] <command> [<args>]

Available commands are:
    build       build image(s) from template
    fix         fixes templates from old versions of packer
    inspect     see components of a template
    push        push a template and supporting files to a Packer build service
    validate    check that a template is valid
    version     Prints the Packer version

 

Help Validate

$ packer --help validate

Usage: packer validate [options] TEMPLATE

  Checks the template is valid by parsing the template and also
  checking the configuration with the various builders, provisioners, etc.

  If it is not valid, the errors will be shown and the command will exit
  with a non-zero exit status. If it is valid, it will exit with a zero
  exit status.

Options:

  -syntax-only           Only check syntax. Do not verify config of the template.
  -except=foo,bar,baz    Validate all builds other than these
  -only=foo,bar,baz      Validate only these builds
  -var 'key=value'       Variable for templates, can be used multiple times.
  -var-file=path         JSON file containing user variables.

 

Help Inspect

Usage: packer inspect TEMPLATE

  Inspects a template, parsing and outputting the components a template
  defines. This does not validate the contents of a template (other than
  basic syntax by necessity).

Options:

  -machine-readable  Machine-readable output

 

Help Build

$ packer --help build

Usage: packer build [options] TEMPLATE

  Will execute multiple builds in parallel as defined in the template.
  The various artifacts created by the template will be outputted.

Options:

  -color=false               Disable color output (on by default)
  -debug                     Debug mode enabled for builds
  -except=foo,bar,baz        Build all builds other than these
  -only=foo,bar,baz          Build only the specified builds
  -force                     Force a build to continue if artifacts exist, deletes existing artifacts
  -machine-readable          Machine-readable output
  -on-error=[cleanup|abort|ask] If the build fails do: clean up (default), abort, or ask
  -parallel=false            Disable parallelization (on by default)
  -var 'key=value'           Variable for templates, can be used multiple times.
  -var-file=path             JSON file containing user variables.

 

Autocompletion

To enable autocompletion

$ packer -autocomplete-install

 

Workflow

.. and terminology.

Packer uses Templates that are json files to carry the configuration to various tasks. The core task is the Build. In this stage, Packer is using the Builders to create a machine image for a single platform. eg. the Qemu Builder to create a kvm/xen virtual machine image. The next stage is provisioning. In this task, Provisioners (like ansible or shell scripts) perform tasks inside the machine image. When finished, Post-processors are handling the final tasks. Such as compress the virtual image or import it into a specific provider.

 

Template

a json template file contains:

• builders (required)
• description (optional)
• variables (optional)
• min_packer_version (optional)
• provisioners (optional)
• post-processors (optional)

also comments are supported only as root level keys

eg.

{
  "_comment": "This is a comment",

  "builders": [
    {}
  ]
}

 

Template Example

eg. Qemu Builder

qemu_example.json

{
  "_comment": "This is a qemu builder example",

  "builders": [
    {
        "type": "qemu"
    }
  ]
}

 

Validate

Syntax Only

$ packer validate -syntax-only  qemu_example.json 

Syntax-only check passed. Everything looks okay.

 

Validate Template

$ packer validate qemu_example.json

Template validation failed. Errors are shown below.

Errors validating build 'qemu'. 2 error(s) occurred:

* One of iso_url or iso_urls must be specified.
* An ssh_username must be specified
  Note: some builders used to default ssh_username to "root".

Template validation failed. Errors are shown below.

Errors validating build 'qemu'. 2 error(s) occurred:

* One of iso_url or iso_urls must be specified.
* An ssh_username must be specified
  Note: some builders used to default ssh_username to "root".

 

Debugging

To enable Verbose logging on the console type:

$ export PACKER_LOG=1

 

Variables

user variables

It is really simple to use variables inside the packer template:

  "variables": {
    "centos_version":  "7.5",
  }    

and use the variable as:

"{{user `centos_version`}}",

 

Description

We can add on top of our template a description declaration:

eg.

  "description": "tMinimal CentOS 7 Qemu Imagen__________________________________________",

and verify it when inspect the template.

 

QEMU Builder

The full documentation on QEMU Builder, can be found here

Qemu template example

Try to keep things simple. Here is an example setup for building a CentOS 7.5 image with packer via qemu.

$ cat qemu_example.json

{

  "_comment": "This is a CentOS 7.5 Qemu Builder example",

  "description": "tMinimal CentOS 7 Qemu Imagen__________________________________________",

  "variables": {
    "7.5":      "1804",
    "checksum": "714acc0aefb32b7d51b515e25546835e55a90da9fb00417fbee2d03a62801efd"
  },

  "builders": [
    {
        "type": "qemu",

        "iso_url": "http://ftp.otenet.gr/linux/centos/7/isos/x86_64/CentOS-7-x86_64-Minimal-{{user `7.5`}}.iso",
        "iso_checksum": "{{user `checksum`}}",
        "iso_checksum_type": "sha256",

        "communicator": "none"
    }
  ]

}

 

Communicator

There are three basic communicators:

• none
• Secure Shell (SSH)
• WinRM

that are configured within the builder section.

Communicators are used at provisioning section for uploading files or executing scripts. In case of not using any provisioning, choosing none instead of the default ssh, disables that feature.

"communicator": "none"

 

iso_url

can be a http url or a file path to a file. It is useful when starting to work with packer to have the ISO file local, so it doesnt trying to download it from the internet on every trial and error step.

eg.

"iso_url": "/home/ebal/Downloads/CentOS-7-x86_64-Minimal-{{user `7.5`}}.iso"

 

Inspect Template

$ packer inspect qemu_example.json

Description:

    Minimal CentOS 7 Qemu Image
__________________________________________

Optional variables and their defaults:

  7.5      = 1804
  checksum = 714acc0aefb32b7d51b515e25546835e55a90da9fb00417fbee2d03a62801efd

Builders:

  qemu

Provisioners:

  <No provisioners>

Note: If your build names contain user variables or template
functions such as 'timestamp', these are processed at build time,
and therefore only show in their raw form here.

Validate Syntax Only

$ packer validate -syntax-only qemu_example.json

Syntax-only check passed. Everything looks okay.

Validate

$ packer validate qemu_example.json

Template validated successfully.

 

Build

Initial Build

$ packer build qemu_example.json

 

 

Build output

the first packer output should be like this:

qemu output will be in this color.

==> qemu: Downloading or copying ISO
    qemu: Downloading or copying: file:///home/ebal/Downloads/CentOS-7-x86_64-Minimal-1804.iso
==> qemu: Creating hard drive...
==> qemu: Looking for available port between 5900 and 6000 on 127.0.0.1
==> qemu: Starting VM, booting from CD-ROM
==> qemu: Waiting 10s for boot...
==> qemu: Connecting to VM via VNC
==> qemu: Typing the boot command over VNC...
==> qemu: Waiting for shutdown...
==> qemu: Converting hard drive...
Build 'qemu' finished.

Use ctrl+c to break and exit the packer build.

 

Automated Installation

The ideal scenario is to automate the entire process, using a Kickstart file to describe the initial CentOS installation. The kickstart reference guide can be found here.

In this example, this ks file CentOS7-ks.cfg can be used.

In the jason template file, add the below configuration:

  "boot_command":[
    "<tab> text ",
    "ks=https://raw.githubusercontent.com/ebal/confs/master/Kickstart/CentOS7-ks.cfg ",
     "nameserver=9.9.9.9 ",
     "<enter><wait> "
],
  "boot_wait": "0s"

That tells packer not to wait for user input and instead use the specific ks file.

 

 

http_directory

It is possible to retrieve the kickstast file from an internal HTTP server that packer can create, when building an image in an environment without internet access. Enable this feature by declaring a directory path: http_directory

Path to a directory to serve using an HTTP server. The files in this directory will be available over HTTP that will be requestable from the virtual machine

eg.

  "http_directory": "/home/ebal/Downloads/",
  "http_port_min": "8090",
  "http_port_max": "8100",

with that, the previous boot command should be written as:

"boot_command":[
    "<tab> text ",
    "ks=http://{{ .HTTPIP }}:{{ .HTTPPort }}/CentOS7-ks.cfg ",
    "<enter><wait>"
],
    "boot_wait": "0s"

 

 

Timeout

A “well known” error with packer is the Waiting for shutdown timeout error.

eg.

==> qemu: Waiting for shutdown...
==> qemu: Failed to shutdown
==> qemu: Deleting output directory...
Build 'qemu' errored: Failed to shutdown

==> Some builds didn't complete successfully and had errors:
--> qemu: Failed to shutdown

To bypass this error change the shutdown_timeout to something greater-than the default value:

By default, the timeout is 5m or five minutes

eg.

"shutdown_timeout": "30m"

ssh

Sometimes the timeout error is on the ssh attemps. If you are using ssh as comminocator, change the below value also:

"ssh_timeout": "30m",

 

qemu_example.json

This is a working template file:

{

  "_comment": "This is a CentOS 7.5 Qemu Builder example",

  "description": "tMinimal CentOS 7 Qemu Imagen__________________________________________",

  "variables": {
    "7.5":      "1804",
    "checksum": "714acc0aefb32b7d51b515e25546835e55a90da9fb00417fbee2d03a62801efd"
  },

  "builders": [
    {
        "type": "qemu",

        "iso_url": "/home/ebal/Downloads/CentOS-7-x86_64-Minimal-{{user `7.5`}}.iso",
        "iso_checksum": "{{user `checksum`}}",
        "iso_checksum_type": "sha256",

        "communicator": "none",

        "boot_command":[
          "<tab> text ",
          "ks=http://{{ .HTTPIP }}:{{ .HTTPPort }}/CentOS7-ks.cfg ",
          "nameserver=9.9.9.9 ",
          "<enter><wait> "
        ],
        "boot_wait": "0s",

        "http_directory": "/home/ebal/Downloads/",
        "http_port_min": "8090",
        "http_port_max": "8100",

        "shutdown_timeout": "20m"

    }
  ]

}

 

build

packer build qemu_example.json

 

Verify

and when the installation is finished, check the output folder & image:

$ ls
output-qemu  packer_cache  qemu_example.json

$ ls output-qemu/
packer-qemu

$ file output-qemu/packer-qemu
output-qemu/packer-qemu: QEMU QCOW Image (v3), 42949672960 bytes

$ du -sh output-qemu/packer-qemu
1.7G    output-qemu/packer-qemu

$ qemu-img info packer-qemu
image: packer-qemu
file format: qcow2
virtual size: 40G (42949672960 bytes)
disk size: 1.7G
cluster_size: 65536
Format specific information:
    compat: 1.1
    lazy refcounts: false
    refcount bits: 16
    corrupt: false

 

KVM

The default qemu/kvm builder will run something like this:

/usr/bin/qemu-system-x86_64
  -cdrom /home/ebal/Downloads/CentOS-7-x86_64-Minimal-1804.iso
  -name packer-qemu -display sdl
  -netdev user,id=user.0
  -vnc 127.0.0.1:32
  -machine type=pc,accel=kvm
  -device virtio-net,netdev=user.0
  -drive file=output-qemu/packer-qemu,if=virtio,cache=writeback,discard=ignore,format=qcow2
  -boot once=d
  -m 512M

In the builder section those qemu/kvm settings can be changed.

Using variables:

eg.

   "virtual_name": "centos7min.qcow2",
   "virtual_dir":  "centos7",
   "virtual_size": "20480",
   "virtual_mem":  "4096M"

In Qemu Builder:

  "accelerator": "kvm",
  "disk_size":   "{{ user `virtual_size` }}",
  "format":      "qcow2",
  "qemuargs":[
    [  "-m",  "{{ user `virtual_mem` }}" ]
  ],

  "vm_name":          "{{ user `virtual_name` }}",
  "output_directory": "{{ user `virtual_dir` }}"

 

Headless

There is no need for packer to use a display. This is really useful when running packer on a remote machine. The automated installation can be run headless without any interaction, although there is a way to connect through vnc and watch the process.

To enable a headless setup:

"headless": true

Serial

Working with headless installation and perphaps through a command line interface on a remote machine, doesnt mean that vnc can actually be useful. Instead there is a way to use a serial output of qemu. To do that, must pass some extra qemu arguments:

eg.

  "qemuargs":[
      [ "-m",      "{{ user `virtual_mem` }}" ],
      [ "-serial", "file:serial.out" ]
    ],

and also pass an extra (kernel) argument console=ttyS0,115200n8 to the boot command:

  "boot_command":[
    "<tab> text ",
    "console=ttyS0,115200n8 ",
    "ks=http://{{ .HTTPIP }}:{{ .HTTPPort }}/CentOS7-ks.cfg ",
    "nameserver=9.9.9.9 ",
    "<enter><wait> "
  ],
  "boot_wait": "0s",

The serial output:

to see the serial output:

$ tail -f serial.out

 

Post-Processors

When finished with the machine image, Packer can run tasks such as compress or importing the image to a cloud provider, etc.

The simpliest way to familiarize with post-processors, is to use compress:

  "post-processors":[
      {
          "type":   "compress",
          "format": "lz4",
          "output": "{{.BuildName}}.lz4"
      }
  ]

 

output

So here is the output:

$ packer build qemu_example.json 

qemu output will be in this color.

==> qemu: Downloading or copying ISO
    qemu: Downloading or copying: file:///home/ebal/Downloads/CentOS-7-x86_64-Minimal-1804.iso
==> qemu: Creating hard drive...
==> qemu: Starting HTTP server on port 8099
==> qemu: Looking for available port between 5900 and 6000 on 127.0.0.1
==> qemu: Starting VM, booting from CD-ROM
    qemu: The VM will be run headless, without a GUI. If you want to
    qemu: view the screen of the VM, connect via VNC without a password to
    qemu: vnc://127.0.0.1:5982
==> qemu: Overriding defaults Qemu arguments with QemuArgs...
==> qemu: Connecting to VM via VNC
==> qemu: Typing the boot command over VNC...
==> qemu: Waiting for shutdown...
==> qemu: Converting hard drive...
==> qemu: Running post-processor: compress
==> qemu (compress): Using lz4 compression with 4 cores for qemu.lz4
==> qemu (compress): Archiving centos7/centos7min.qcow2 with lz4
==> qemu (compress): Archive qemu.lz4 completed
Build 'qemu' finished.

==> Builds finished. The artifacts of successful builds are:
--> qemu: compressed artifacts in: qemu.lz4

 

info

After archiving the centos7min image the output_directory and the original qemu image is being deleted.

$ qemu-img info ./centos7/centos7min.qcow2

image: ./centos7/centos7min.qcow2
file format: qcow2
virtual size: 20G (21474836480 bytes)
disk size: 1.5G
cluster_size: 65536
Format specific information:
    compat: 1.1
    lazy refcounts: false
    refcount bits: 16
    corrupt: false

$ du -h qemu.lz4
992M    qemu.lz4

 

Provisioners

Last but -surely- not least packer supports Provisioners.
Provisioners are commonly used for:

• installing packages
• patching the kernel
• creating users
• downloading application code

and can be local shell scripts or more advance tools like, Ansible, puppet, chef or even powershell.

 

Ansible

So here is an ansible example:

$ tree testrole

testrole
├── defaults
│   └── main.yml
├── files
│   └── main.yml
├── handlers
│   └── main.yml
├── meta
│   └── main.yml
├── tasks
│   └── main.yml
├── templates
│   └── main.yml
└── vars
    └── main.yml

7 directories, 7 files

$ cat testrole/tasks/main.yml 

---
  - name: Debug that our ansible role is working
    debug:
      msg: "It Works !"

  - name: Install the Extra Packages for Enterprise Linux repository
    yum:
      name: epel-release
      state: present

  - name: upgrade all packages
    yum:
      name: '*'
      state: latest

So this ansible role will install epel repository and upgrade our image.

template

    "variables":{
        "playbook_name": "testrole.yml"
    },

...

    "provisioners":[
        {
            "type":          "ansible",
            "playbook_file": "{{ user `playbook_name` }}"
        }
    ],

Communicator

Ansible needs to ssh into this machine to provision it. It is time to change the communicator from none to ssh.

  "communicator": "ssh",

Need to add the ssh username/password to template file:

      "ssh_username": "root",
      "ssh_password": "password",
      "ssh_timeout":  "3600s",

 

output

$ packer build qemu_example.json

qemu output will be in this color.

==> qemu: Downloading or copying ISO
    qemu: Downloading or copying: file:///home/ebal/Downloads/CentOS-7-x86_64-Minimal-1804.iso
==> qemu: Creating hard drive...
==> qemu: Starting HTTP server on port 8100
==> qemu: Found port for communicator (SSH, WinRM, etc): 4105.
==> qemu: Looking for available port between 5900 and 6000 on 127.0.0.1
==> qemu: Starting VM, booting from CD-ROM
    qemu: The VM will be run headless, without a GUI. If you want to
    qemu: view the screen of the VM, connect via VNC without a password to
    qemu: vnc://127.0.0.1:5990
==> qemu: Overriding defaults Qemu arguments with QemuArgs...
==> qemu: Connecting to VM via VNC
==> qemu: Typing the boot command over VNC...
==> qemu: Waiting for SSH to become available...
==> qemu: Connected to SSH!
==> qemu: Provisioning with Ansible...
==> qemu: Executing Ansible: ansible-playbook --extra-vars packer_build_name=qemu packer_builder_type=qemu -i /tmp/packer-provisioner-ansible594660041 /opt/hashicorp/packer/testrole.yml -e ansible_ssh_private_key_file=/tmp/ansible-key802434194
    qemu:
    qemu: PLAY [all] *********************************************************************
    qemu:
    qemu: TASK [testrole : Debug that our ansible role is working] ***********************
    qemu: ok: [default] => {
    qemu:     "msg": "It Works !"
    qemu: }
    qemu:
    qemu: TASK [testrole : Install the Extra Packages for Enterprise Linux repository] ***
    qemu: changed: [default]
    qemu:
    qemu: TASK [testrole : upgrade all packages] *****************************************
    qemu: changed: [default]
    qemu:
    qemu: PLAY RECAP *********************************************************************
    qemu: default                    : ok=3    changed=2    unreachable=0    failed=0
    qemu:
==> qemu: Halting the virtual machine...
==> qemu: Converting hard drive...
==> qemu: Running post-processor: compress
==> qemu (compress): Using lz4 compression with 4 cores for qemu.lz4
==> qemu (compress): Archiving centos7/centos7min.qcow2 with lz4
==> qemu (compress): Archive qemu.lz4 completed
Build 'qemu' finished.

==> Builds finished. The artifacts of successful builds are:
--> qemu: compressed artifacts in: qemu.lz4

 

Appendix

here is the entire qemu template file:

qemu_example.json

{

  "_comment": "This is a CentOS 7.5 Qemu Builder example",

  "description": "tMinimal CentOS 7 Qemu Imagen__________________________________________",

  "variables": {
    "7.5":      "1804",
    "checksum": "714acc0aefb32b7d51b515e25546835e55a90da9fb00417fbee2d03a62801efd",

     "virtual_name": "centos7min.qcow2",
     "virtual_dir":  "centos7",
     "virtual_size": "20480",
     "virtual_mem":  "4096M",

     "Password": "password",

     "ansible_playbook": "testrole.yml"
  },

  "builders": [
    {
        "type": "qemu",

        "headless": true,

        "iso_url": "/home/ebal/Downloads/CentOS-7-x86_64-Minimal-{{user `7.5`}}.iso",
        "iso_checksum": "{{user `checksum`}}",
        "iso_checksum_type": "sha256",

        "communicator": "ssh",

        "ssh_username": "root",
        "ssh_password": "{{user `Password`}}",
        "ssh_timeout":  "3600s",

        "boot_command":[
          "<tab> text ",
          "console=ttyS0,115200n8 ",
          "ks=http://{{ .HTTPIP }}:{{ .HTTPPort }}/CentOS7-ks.cfg ",
          "nameserver=9.9.9.9 ",
          "<enter><wait> "
        ],
        "boot_wait": "0s",

        "http_directory": "/home/ebal/Downloads/",
        "http_port_min": "8090",
        "http_port_max": "8100",

        "shutdown_timeout": "30m",

    "accelerator": "kvm",
    "disk_size":   "{{ user `virtual_size` }}",
    "format":      "qcow2",
    "qemuargs":[
        [ "-m",      "{{ user `virtual_mem` }}" ],
            [ "-serial", "file:serial.out" ]
    ],

        "vm_name":          "{{ user `virtual_name` }}",
        "output_directory": "{{ user `virtual_dir` }}"
    }
  ],

  "provisioners":[
    {
      "type":          "ansible",
      "playbook_file": "{{ user `ansible_playbook` }}"
    }
  ],

  "post-processors":[
      {
          "type":   "compress",
          "format": "lz4",
          "output": "{{.BuildName}}.lz4"
      }
  ]
}

 

CentOS 6

This way is been suggested for building a container image from your current centos system.

 

In my case, I need to remote upgrade a running centos6 system to a new clean centos7 on a test vps, without the need of opening the vnc console, attaching a new ISO etc etc.

I am rather lucky as I have a clean extra partition to this vps, so I will follow the below process to remote install a new clean CentOS 7 to this partition. Then add a new grub entry and boot into this partition.

 

Current OS

# cat /etc/redhat-release
CentOS release 6.9 (Final)

 

Format partition

format & mount the partition:

 mkfs.ext4 -L rootfs /dev/vda5
 mount /dev/vda5 /mnt/

 

InstallRoot

Type:

# yum -y groupinstall "Base" --releasever 7 --installroot /mnt/ --nogpgcheck

 

Test

test it, when finished:

mount --bind /dev/  /mnt/dev/
mount --bind /sys/  /mnt/sys/
mount --bind /proc/ /mnt/proc/

chroot /mnt/

bash-4.2#  cat /etc/redhat-release
CentOS Linux release 7.5.1804 (Core)

It works!

 

Root Password

inside chroot enviroment:

bash-4.2# passwd
Changing password for user root.
New password:
Retype new password:
passwd: all authentication tokens updated successfully.

bash-4.2# exit

 

Grub

adding the new grub entry for CentOS 7

title CentOS 7
        root (hd0,4)
        kernel /boot/vmlinuz-3.10.0-862.2.3.el7.x86_64 root=/dev/vda5 ro rhgb LANG=en_US.UTF-8
        initrd /boot/initramfs-3.10.0-862.2.3.el7.x86_64.img

by changing the default boot entry from 0 to 1 :

default=0

to

default=1

our system will boot into centos7 when reboot!

 

Prologue

 

Maintaining a (public) service can be sometimes troublesome. In case of email service, often you need to suspend or restrict users for reasons like SPAM, SCAM or Phishing. You have to deal with inactive or even compromised accounts. Protecting your infrastructure is to protect your active users and the service. In this article I’ll propose a way to restrict messages to authorized addresses when sending an email and get a bounce message explaining why their email was not sent.

 

Reading Material

The reference documentation when having a Directory Service (LDAP) as our user backend and using Postfix:

• Postfix - SMTPD_ACCESS
• Postfix - LDAP

 

LDAP

In this post, we will not get into openldap internals but as reference I’ll show an example user account (this is from my working test lab).

 

dn: uid=testuser2,ou=People,dc=example,dc=org
objectClass: top
objectClass: person
objectClass: organizationalPerson
objectClass: inetOrgPerson
objectClass: posixAccount
mail: testuser2@example.org
smtpd_sender_restrictions: true
cn: Evaggelos Balaskas
sn: Balaskas
givenName: Evaggelos
uidNumber: 99
gidNumber: 12
uid: testuser2
homeDirectory: /storage/vhome/%d/%n
userPassword: XXXXXXXXXX

as you can see, we have a custom ldap attribute:

smtpd_sender_restrictions: true

keep that in mind for now.

 

Postfix

The default value of smtpd_sender_restrictions is empty, that means by default the mail server has no sender restrictions. Depending on the policy we either can whitelist or blacklist in postfix restrictions, for the purpose of this blog post, we will only restrict (blacklist) specific user accounts.

 

ldap_smtpd_sender_restrictions

To do that, let’s create a new file that will talk to our openldap and ask for that specific ldap attribute.

ldap_smtpd_sender_restrictions.cf

server_host = ldap://localhost
server_port = 389
search_base = ou=People,dc=example,dc=org
query_filter = (&(smtpd_sender_restrictions=true)(mail=%s))
result_attribute = uid
result_filter = uid
result_format = REJECT This account is not allowed to send emails, plz talk to abuse@example.org
version = 3
timeout = 5

This is an anonymous bind, as we do not search for any special attribute like password.

 

Status Codes

The default status code will be: 554 5.7.1
Take a look here for more info: RFC 3463 - Enhanced Mail System Status Codes

 

Test it

# postmap -q testuser2@example.org ldap:/etc/postfix/ldap_smtpd_sender_restrictions.cf
REJECT This account is not allowed to send emails, plz talk to abuse@example.org

Add -v to extent verbosity

# postmap -v -q testuser2@example.org ldap:/etc/postfix/ldap_smtpd_sender_restrictions.cf

 

Possible Errors

postmap: fatal: unsupported dictionary type: ldap

Check your postfix setup with postconf -m . The result should be something like this:

btree
cidr
environ
fail
hash
internal
ldap
memcache
nis
proxy
regexp
socketmap
static
tcp
texthash
unix

If not, you need to setup postfix to support the ldap dictionary type.

 

smtpd_sender_restrictions

Modify the main.cf to add the ldap_smtpd_sender_restrictions.cf

# applied in the context of the MAIL FROM
smtpd_sender_restrictions =
        check_sender_access ldap:/etc/postfix/ldap_smtpd_sender_restrictions.cf

and reload postfix

# postfix reload

If you keep logs, tail them to see any errors.

 

Thunderbird

 

Logs

May 19 13:20:26 centos6 postfix/smtpd[20905]:
NOQUEUE: reject: RCPT from XXXXXXXX[XXXXXXXX]: 554 5.7.1 <testuser2@example.org>:
Sender address rejected: This account is not allowed to send emails, plz talk to abuse@example.org;
from=<testuser2@example.org> to=<postmaster@example.org> proto=ESMTP helo=<[192.168.0.13]>

Prologue

Security

One of the most common security concerns (especially when traveling) is the attach of unknown USB device on our system.

There are a few ways on how to protect your system.

 

Hardware Protection

• usbkill
• silk-guardian
• USB Condom

 

Cloud Storage

More and more companies are now moving from local storage to cloud storage as a way to reduce the attack surface on systems:

IBM a few days ago, banned portable storage devices

• IBM Employees Can’t Use Removable Storage Anymore

 

Hot Glue on USB Ports

also we must not forget the old but powerful advice from security researches & hackers:

by inserting glue or using a Hot Glue Gun to disable the USB ports of a system.

Problem solved!

 

USBGuard

I was reading the redhat 7.5 release notes and I came upon on usbguard:

• Using USBGuard
• Blocking USB devices while the screen is locked

 

USBGuard

The USBGuard software framework helps to protect your computer against rogue USB devices (a.k.a. BadUSB) by implementing basic whitelisting / blacklisting capabilities based on device attributes.

 

USB protection framework

So the main idea is you run a daemon on your system that tracks udev monitor system. The idea seams like the usb kill switch but in a more controlled manner. You can dynamical whitelist or/and blacklist devices and change the policy on such devices more easily. Also you can do all that via a graphical interface, although I will not cover it here.

 

Archlinux Notes

for archlinux users, you can find usbguard in AUR (Archlinux User Repository)

AUR : usbguard

or you can try my custom PKGBUILDs files

• USBGuard/PKGBUILD
• libqb/PKGBUILD

 

How to use usbguard

Generate Policy

The very first thing is to generate a policy with the current attached USB devices.

sudo usbguard generate-policy

Below is an example output, viewing my usb mouse & usb keyboard :

allow id 17ef:6019 serial "" name "Lenovo USB Optical Mouse" hash "WXaMPh5VWHf9avzB+Jpua45j3EZK6KeLRdPcoEwlWp4=" parent-hash "jEP/6WzviqdJ5VSeTUY8PatCNBKeaREvo2OqdplND/o=" via-port "3-4" with-interface 03:01:02

allow id 045e:00db serial "" name "Naturalxc2xae Ergonomic Keyboard 4000" hash "lwGc9o+VaG/2QGXpZ06/2yHMw+HL46K8Vij7Q65Qs80=" parent-hash "kv3v2+rnq9QvYI3/HbJ1EV9vdujZ0aVCQ/CGBYIkEB0=" via-port "1-1.5" with-interface { 03:01:01 03:00:00 }

The default policy for already attached USB devices are allow.

 

We can create our rules configuration file by:

sudo usbguard generate-policy > /etc/usbguard/rules.conf

 

Service

starting and enabling usbguard service via systemd:

systemctl start usbguard.service

systemctl enable usbguard.service

 

List of Devices

You can view the list of attached USB devices and

sudo usbguard list-devices

 

Allow Device

Attaching a new USB device (in my case, my mobile phone):

$ sudo usbguard list-devices | grep -v allow

we will see that the default policy is to block it:

17: block id 12d1:107e serial "7BQDU17308005969" name "BLN-L21" hash "qq1bdaK0ETC/thKW9WXAwawhXlBAWUIowpMeOQNGQiM=" parent-hash "kv3v2+rnq9QvYI3/HbJ1EV9vdujZ0aVCQ/CGBYIkEB0=" via-port "2-1.5" with-interface { ff:ff:00 08:06:50 }

So we can allow it by:

sudo usbguard allow-device 17

then

sudo usbguard list-devices | grep BLN-L21

we can verify that is okay:

17: allow id 12d1:107e serial "7BQDU17308005969" name "BLN-L21" hash "qq1bdaK0ETC/thKW9WXAwawhXlBAWUIowpMeOQNGQiM=" parent-hash "kv3v2+rnq9QvYI3/HbJ1EV9vdujZ0aVCQ/CGBYIkEB0=" via-port "2-1.5" with-interface { ff:ff:00 08:06:50 }

 

Block USB on screen lock

The default policy, when you (or someone else) are inserting a new USB device is:

sudo usbguard get-parameter InsertedDevicePolicy
apply-policy

is to apply the default policy we have. There is a way to block or reject any new USB device when you have your screen locker on, as this may be a potential security attack on your system. In theory, you are inserting USB devices as you are working on your system, and not when you have your screen lock on.

I use slock as my primary screen locker via a keyboard shortcut. So the easiest way to dynamical change the default policy on usbguard is via a shell wrapper:

vim /usr/local/bin/slock

#!/bin/sh

# ebal, Sun, 13 May 2018 10:07:53 +0300
POLICY_UNLOCKED="apply-policy"
POLICY_LOCKED="reject"

# function to revert the policy
revert() {
  usbguard set-parameter InsertedDevicePolicy ${POLICY_UNLOCKED}
}

trap revert SIGHUP SIGINT SIGTERM
usbguard set-parameter InsertedDevicePolicy ${POLICY_LOCKED}

/usr/bin/slock

# shell function to revert reject policy
revert

(you can find the same example on redhat’s blog post).

Upgrading CentOS 6.x to CentOS 7.x

 

Disclaimer : Create a recent backup of the system. This is an unofficial , unsupported procedure !

 

CentOS 6

CentOS release 6.9 (Final)
Kernel 2.6.32-696.16.1.el6.x86_64 on an x86_64

centos69 login: root
Password:
Last login: Tue May  8 19:45:45 on tty1

[root@centos69 ~]# cat /etc/redhat-release
CentOS release 6.9 (Final)

 

Pre Tasks

There are some tasks you can do to prevent from unwanted results.
Like:

• Disable selinux
• Remove unnecessary repositories
• Take a recent backup!

 

CentOS Upgrade Repository

Create a new centos repository:

cat > /etc/yum.repos.d/centos-upgrade.repo <<EOF
[centos-upgrade]
name=centos-upgrade
baseurl=http://dev.centos.org/centos/6/upg/x86_64/
enabled=1
gpgcheck=0
EOF

 

Install Pre-Upgrade Tool

First install the openscap version from dev.centos.org:

# yum -y install https://buildlogs.centos.org/centos/6/upg/x86_64/Packages/openscap-1.0.8-1.0.1.el6.centos.x86_64.rpm

then install the redhat upgrade tool:

# yum -y install redhat-upgrade-tool preupgrade-assistant-*

 

Import CentOS 7 PGP Key

# rpm --import http://ftp.otenet.gr/linux/centos/RPM-GPG-KEY-CentOS-7 

 

Mirror

to bypass errors like:

Downloading failed: invalid data in .treeinfo: No section: ‘checksums’

append CentOS Vault under mirrorlist:

 mkdir -pv /var/tmp/system-upgrade/base/ /var/tmp/system-upgrade/extras/  /var/tmp/system-upgrade/updates/

 echo http://vault.centos.org/7.0.1406/os/x86_64/       >  /var/tmp/system-upgrade/base/mirrorlist.txt
 echo http://vault.centos.org/7.0.1406/extras/x86_64/   >  /var/tmp/system-upgrade/extras/mirrorlist.txt
 echo http://vault.centos.org/7.0.1406/updates/x86_64/  >  /var/tmp/system-upgrade/updates/mirrorlist.txt 

These are enough to upgrade to 7.0.1406. You can add the below mirros, to upgrade to 7.5.1804

More Mirrors

 echo http://ftp.otenet.gr/linux/centos/7.5.1804/os/x86_64/  >>  /var/tmp/system-upgrade/base/mirrorlist.txt
 echo http://mirror.centos.org/centos/7/os/x86_64/           >>  /var/tmp/system-upgrade/base/mirrorlist.txt 

 echo http://ftp.otenet.gr/linux/centos/7.5.1804/extras/x86_64/ >>  /var/tmp/system-upgrade/extras/mirrorlist.txt
 echo http://mirror.centos.org/centos/7/extras/x86_64/          >>  /var/tmp/system-upgrade/extras/mirrorlist.txt 

 echo http://ftp.otenet.gr/linux/centos/7.5.1804/updates/x86_64/  >>  /var/tmp/system-upgrade/updates/mirrorlist.txt
 echo http://mirror.centos.org/centos/7/updates/x86_64/           >>  /var/tmp/system-upgrade/updates/mirrorlist.txt 

 

Pre-Upgrade

preupg is actually a python script!

# yes | preupg -v 

Preupg tool doesn't do the actual upgrade.
Please ensure you have backed up your system and/or data in the event of a failed upgrade
 that would require a full re-install of the system from installation media.
Do you want to continue? y/n
Gathering logs used by preupgrade assistant:
All installed packages : 01/11 ...finished (time 00:00s)
All changed files      : 02/11 ...finished (time 00:18s)
Changed config files   : 03/11 ...finished (time 00:00s)
All users              : 04/11 ...finished (time 00:00s)
All groups             : 05/11 ...finished (time 00:00s)
Service statuses       : 06/11 ...finished (time 00:00s)
All installed files    : 07/11 ...finished (time 00:01s)
All local files        : 08/11 ...finished (time 00:01s)
All executable files   : 09/11 ...finished (time 00:01s)
RedHat signed packages : 10/11 ...finished (time 00:00s)
CentOS signed packages : 11/11 ...finished (time 00:00s)
Assessment of the system, running checks / SCE scripts:
001/096 ...done    (Configuration Files to Review)
002/096 ...done    (File Lists for Manual Migration)
003/096 ...done    (Bacula Backup Software)
...
./result.html
/bin/tar: .: file changed as we read it
Tarball with results is stored here /root/preupgrade-results/preupg_results-180508202952.tar.gz .
The latest assessment is stored in directory /root/preupgrade .
Summary information:
We found some potential in-place upgrade risks.
Read the file /root/preupgrade/result.html for more details.
Upload results to UI by command:
e.g. preupg -u http://127.0.0.1:8099/submit/ -r /root/preupgrade-results/preupg_results-*.tar.gz .

this must finish without any errors.

 

CentOS Upgrade Tool

We need to find out what are the possible problems when upgrade:

# centos-upgrade-tool-cli --network=7
          --instrepo=http://vault.centos.org/7.0.1406/os/x86_64/ 

 

Then by force we can upgrade to it’s latest version:

# centos-upgrade-tool-cli --force --network=7
          --instrepo=http://vault.centos.org/7.0.1406/os/x86_64/
          --cleanup-post

 

Output

setting up repos...
base                                                          | 3.6 kB     00:00
base/primary_db                                               | 4.9 MB     00:04
centos-upgrade                                                | 1.9 kB     00:00
centos-upgrade/primary_db                                     |  14 kB     00:00
cmdline-instrepo                                              | 3.6 kB     00:00
cmdline-instrepo/primary_db                                   | 4.9 MB     00:03
epel/metalink                                                 |  14 kB     00:00
epel                                                          | 4.7 kB     00:00
epel                                                          | 4.7 kB     00:00
epel/primary_db                                               | 6.0 MB     00:04
extras                                                        | 3.6 kB     00:00
extras/primary_db                                             | 4.9 MB     00:04
mariadb                                                       | 2.9 kB     00:00
mariadb/primary_db                                            |  33 kB     00:00
remi-php56                                                    | 2.9 kB     00:00
remi-php56/primary_db                                         | 229 kB     00:00
remi-safe                                                     | 2.9 kB     00:00
remi-safe/primary_db                                          | 950 kB     00:00
updates                                                       | 3.6 kB     00:00
updates/primary_db                                            | 4.9 MB     00:04
.treeinfo                                                     | 1.1 kB     00:00
getting boot images...
vmlinuz-redhat-upgrade-tool                                   | 4.7 MB     00:03
initramfs-redhat-upgrade-tool.img                             |  32 MB     00:24
setting up update...
finding updates 100% [=========================================================]
(1/323): MariaDB-10.2.14-centos6-x86_64-client.rpm            |  48 MB     00:38
(2/323): MariaDB-10.2.14-centos6-x86_64-common.rpm            | 154 kB     00:00
(3/323): MariaDB-10.2.14-centos6-x86_64-compat.rpm            | 4.0 MB     00:03
(4/323): MariaDB-10.2.14-centos6-x86_64-server.rpm            | 109 MB     01:26
(5/323): acl-2.2.51-12.el7.x86_64.rpm                         |  81 kB     00:00
(6/323): apr-1.4.8-3.el7.x86_64.rpm                           | 103 kB     00:00
(7/323): apr-util-1.5.2-6.el7.x86_64.rpm                      |  92 kB     00:00
(8/323): apr-util-ldap-1.5.2-6.el7.x86_64.rpm                 |  19 kB     00:00
(9/323): attr-2.4.46-12.el7.x86_64.rpm                        |  66 kB     00:00
...
(320/323): yum-plugin-fastestmirror-1.1.31-24.el7.noarch.rpm  |  28 kB     00:00
(321/323): yum-utils-1.1.31-24.el7.noarch.rpm                 | 111 kB     00:00
(322/323): zlib-1.2.7-13.el7.x86_64.rpm                       |  89 kB     00:00
(323/323): zlib-devel-1.2.7-13.el7.x86_64.rpm                 |  49 kB     00:00
testing upgrade transaction
rpm transaction 100% [=========================================================]
rpm install 100% [=============================================================]
setting up system for upgrade
Finished. Reboot to start upgrade.

 

Reboot

The upgrade procedure, will download all rpm packages to a directory and create a new grub entry. Then on reboot the system will try to upgrade the distribution release to it’s latest version.

# reboot 

 

Upgrade

CentOS 7

CentOS Linux 7 (Core)
Kernel 3.10.0-123.20.1.el7.x86_64 on an x86_64

centos69 login: root
Password:
Last login: Fri May 11 15:42:30 on ttyS0

[root@centos69 ~]# cat /etc/redhat-release
CentOS Linux release 7.0.1406 (Core)

 

Domain Name Service Response Policy Zones

from PowerDNS Recursor documentation :

Response Policy Zone is an open standard developed by Paul Vixie (ISC and Farsight) and Vernon Schryver (Rhyolite), to modify DNS responses based on a policy loaded via a zonefile.

Sometimes it is called: DNS Firewall

Reading Material

aka useful links:

• DNS Response Policy Zones
• Response Policy Zones (RPZ)
• rpz | PowerDNS Blog

Scheme

An example scheme to get a a better understanding on the concept behind RPZ.

Purpose

The main purposes of implentanting DNS RPZ in your DNS Infrastructure are to dynamicaly DNS sinkhole:

• Malicious domains,
• Implement goverment regulations,
• Prevent users to visit domains that are blocked via legal reasons.

by maintaining a single RPZ zone (or many) or even getting a subscription from another cloud provider.

Althouth for SOHO enviroments I suggest reading this blog post: Removing Ads with your PowerDNS Resolver and customize it to your needs.

RPZ Policies

These are the RPZ Policies we can use with PowerDNS.

• Policy.Custom (default policy)
• Policy.Drop
• Policy.NXDOMAIN
• Policy.NODATA
• Policy.Truncate
• Policy.NoAction

Policy.Custom:

Will return a NoError, CNAME answer with the value specified with
defcontent, when looking up the result of this CNAME, RPZ is not taken into account

Use Case

Modify the DNS responces with a list of domains to a specific sinkhole dns record.

eg.

  thisismytestdomain.com.org ---> sinkhole.example.net.
*.thisismytestdomain.com.org ---> sinkhole.example.net.
  example.org                ---> sinkhole.example.net.
*.example.org                ---> sinkhole.example.net.
  example.net                ---> sinkhole.example.net.
*.example.net                ---> sinkhole.example.net.

DNS sinkhole record

Create an explicit record outside of the DNS RPZ scheme.

A type A Resource Record to a domain zone that points to 127.0.0.1 is okay, or use an explicit host file that the resolver can read. In the PowerDNS Recursor the configuration for this, are these two lines:

etc-hosts-file=/etc/pdns-recursor/hosts.blocked
export-etc-hosts=on

then

$ echo "127.0.0.5 sinkhole.example.net" >> /etc/pdns-recursor/hosts.blocked

and reload the service.

rpz.zone

RPZ functionality is set by reading a bind dns zone file, so create a simple file:

/etc/pdns-recursor/rpz.zone

; Time To Live
$TTL 86400

; Start Of Authorite
@       IN  SOA authns.localhost. hostmaster. 2018042901 14400 7200 1209600 86400

; Declare Name Server
@                    IN  NS      authns.localhost.

Lua

RPZ support configuration is done via our Lua configuration mechanism

In the pdns-recursor configuration file: /etc/pdns-recursor/recursor.conf we need to declare a lua configuration file:

lua-config-file=/etc/pdns-recursor/rpz.lua

Lua-RPZ Configuration file

that points to the rpz.zone file. In this example, we will use Policy.Custom to send every DNS query to our default content: sinkhole.example.net

/etc/pdns-recursor/rpz.lua

rpzFile("/etc/pdns-recursor/rpz.zone", {defpol=Policy.Custom, defcontent="sinkhole.example.net."})

Restart PowerDNS Recursor

At this moment, restart the powerdns recusor

# systemctl restart pdns-recursor

or

# service pdns-recursor restart

and watch for any error log.

Domains to sinkhole

Append to the rpz.zone all the domains you need to sinkhole. The defcontent="sinkhole.example.net." will ignore the content of the zone, but records must be valid, or else pdns-recursor will not read the rpz bind zone file.

; Time To Live
$TTL 86400

; Start Of Authorite
@   IN  SOA authns.localhost. hostmaster. 2018042901 14400 7200 1209600 86400

; Declare Name Server
@                    IN  NS      authns.localhost.

; Domains to sinkhole
thisisatestdomain.org.  IN  CNAME    sinkhole.example.net.
thisisatestdomain.org.  IN  CNAME    sinkhole.example.net.
example.org.            IN  CNAME    sinkhole.example.net.
*.example.org.          IN  CNAME    sinkhole.example.net.
example.net.            IN  CNAME    sinkhole.example.net.
*.example.net.          IN  CNAME    sinkhole.example.net.

When finished, you can reload the lua configuration file that read the rpz.zone file, without restarting the powerdns recursor.

# rec_control reload-lua-config

Verify with dig

testing the dns results with dig:

$ dig example.net.

;; QUESTION SECTION:
;example.net.           IN  A

;; ANSWER SECTION:
example.net.        86400   IN  CNAME   sinkhole.example.net.
sinkhole.example.net.   86261   IN  A   127.0.0.5

$ dig thisisatestdomain.org

;; QUESTION SECTION:
;thisisatestdomain.org.     IN  A

;; ANSWER SECTION:
thisisatestdomain.org.  86400   IN  CNAME   sinkhole.example.net.
sinkhole.example.net.   86229   IN  A   127.0.0.5

Wildcard

test the wildcard record in rpz.zone:

$ dig example.example.net.

;; QUESTION SECTION:
;example.example.net.       IN  A

;; ANSWER SECTION:
example.example.net.    86400   IN  CNAME   sinkhole.example.net.
sinkhole.example.net.   86400   IN  A   127.0.0.5

Recently I needed to create a Nested Loop in Ansible. One of the possible issues I had to consider, was the backward compatibility with both Ansible v1 and Ansible v2. A few days after, Ansible 2.5 introduced the the loop keyword and you can read a comprehensive blog entry here: Loop: Plays in the future, items in the past.

So here are my notes on the subject:

Variables

Below is a variable yaml file for testing purposes:

vars.yml

---
  days:
  - Monday
  - Tuesday
  - Wednesday
  - Thursday
  - Friday
  - Saturday
  - Sunday
  months:
  - January
  - February
  - March
  - April
  - May
  - June
  - July
  - August
  - September
  - October
  - November
  - December

Ansible v1

Let’s start with Ansible v1:

# ansible --version

ansible 1.9.6
  configured module search path = None

Playbook

Below a very simple ansible-playbook example that supports nested loops:

---
- hosts: localhost
  gather_facts: no

  vars_files:
    - vars.yml

  tasks:
   - name: "This is a simple test"
     debug:
       msg: "Day: {{ item[0] }} exist in Month: {{ item[1] }}"
     with_nested:
       - "{{ days }}"
       - "{{ months }}"

This playbook doesnt do much.
Prints a message for every day and every month.

Ansible-Playbook

Run locally the playbook by:

# ansible-playbook nested.yml -c local -l localhost -i "localhost," 

the output:

PLAY [localhost] ****************************** 

TASK: [This is a simple test] *****************
ok: [localhost] => (item=['Monday', 'January']) => {
    "item": [
        "Monday",
        "January"
    ],
    "msg": "Day: Monday exist in Month: January"
}
...
ok: [localhost] => (item=['Sunday', 'December']) => {
    "item": [
        "Sunday",
        "December"
    ],
    "msg": "Day: Sunday exist in Month: December"
}

PLAY RECAP *************************************
localhost                  : ok=1    changed=0    unreachable=0    failed=0

Messages

There are seven (7) days and twelve (12) months, so the output must print: 7*12 = 84 messages.

Counting the messages:

# ansible-playbook nested.yml -c local -l localhost -i "localhost," | egrep -c msg

84

Time

Measuring the time it needs to pass through the nested-loop:

time ansible-playbook nested.yml -c local -l localhost -i "localhost," &> /dev/null 

real 0m0.448s
user 0m0.406s
sys  0m0.040s

0.448s nice!

Ansible v2

Running the same playbook in latest ansible:

# ansible-playbook nested.yml -c local -l localhost

seems to still work!

Compatibility issues: Resolved!

Counting the messages

# ansible-playbook nested.yml | egrep -c msg

84

Time

# time ansible-playbook nested.yml &> /dev/null 

real 0m7.396s
user 0m7.575s
sys  0m0.172s

7.396s !!!

that is 7seconds more than ansible v1.

Complex Loops

The modern way, is to use the loop keyword with the nested lookup plugin:

---
- hosts: localhost
  gather_facts: no

  vars_files:
    - vars.yml

  tasks:
   - name: "This is a simple test"
     debug:
       msg: "Day: {{ item[0] }} exist in Month: {{ item[1] }}"
     loop: "{{ lookup('nested', days, month) }}"

Time

# time ansible-playbook lookup_loop.yml &> /dev/null 

real 0m7.975s
user 0m8.169s
sys  0m0.177s

7.623s

[notes based on a docker centos5]

# cat /etc/redhat-release

CentOS release 5.11 (Final)

Setup Enviroment

Install compiler:

# yum -y install gcc make

Install zlib headers:

# yum -y install zlib-devel

Install tools:

# yum -y install curl unzip

SSL/TLS Errors

If you are on a CentOS 5x machine, when trying to download files from the internet, you will get this error msg:

This is a brown out of TLSv1 support. TLSv1 support is going away soon, upgrade to a TLSv1.2+ capable client.

or

SSL routines:SSL23_GET_SERVER_HELLO:tlsv1 alert protocol version

that is because CentOS 5x has an old cipher suite that doesnt work with today’s standards.

OpenSSL

To bypass these SSL/TLS errors, we need to install a recent version of openssl.

# cd /root/

# curl -LO https://www.openssl.org/source/openssl-1.0.2o.tar.gz
# tar xf openssl*.tar.gz
# cd openssl*

# ./Configure shared linux-x86_64
# make
# make install

The output has a useful info:

OpenSSL shared libraries have been installed in:
  /usr/local/ssl

So, we have to update the system’s library paths, to include this one:

# echo "/usr/local/ssl/lib/" >> /etc/ld.so.conf
# /sbin/ldconfig

Python 2.7

Download the latest Python2.7

# cd /root/
# curl -LO https://www.python.org/ftp/python/2.7.14/Python-2.7.14.tgz
# tar xf Python*.tgz
# cd Python*

Install Python:

# ./configure --prefix=/opt/Python27 --enable-shared
# make
# make install

PATH

# export PATH=/opt/Python27/bin/:$PATH

# python -c "import ssl; print(ssl.OPENSSL_VERSION)"

OpenSSL 1.0.2o  27 Mar 2018

SetupTools

Download the latest setuptools

# cd /root/

# export PYTHONHTTPSVERIFY=0
# python -c 'import urllib; urllib.urlretrieve ("https://pypi.python.org/packages/72/c2/c09362ab29338413ab687b47dab03bab4a792e2bbb727a1eb5e0a88e3b86/setuptools-39.0.1.zip", "setuptools-39.0.1.zip")'

Install setuptools

# unzip setuptools*.zip
# cd setuptools*

# python2.7 setup.py build
# python2.7 setup.py install

PIP

Install PIP

# cd /root/

# easy_install pip

Searching for pip
Reading https://pypi.python.org/simple/pip/
Downloading https://pypi.python.org/packages/4b/5a/8544ae02a5bd28464e03af045e8aabde20a7b02db1911a9159328e1eb25a/pip-10.0.0b1-py2.py3-none-any.whl#md5=34dd54590477e79bc681d9ff96b9fd39
Best match: pip 10.0.0b1
Processing pip-10.0.0b1-py2.py3-none-any.whl
Installing pip-10.0.0b1-py2.py3-none-any.whl to /opt/Python27/lib/python2.7/site-packages
writing requirements to /opt/Python27/lib/python2.7/site-packages/pip-10.0.0b1-py2.7.egg/EGG-INFO/requires.txt
Adding pip 10.0.0b1 to easy-install.pth file
Installing pip script to /opt/Python27/bin
Installing pip3.6 script to /opt/Python27/bin
Installing pip3 script to /opt/Python27/bin

Installed /opt/Python27/lib/python2.7/site-packages/pip-10.0.0b1-py2.7.egg
Processing dependencies for pip
Finished processing dependencies for pip

Ansible

Now, we are ready to install ansible

# pip install ansible

Collecting ansible

/opt/Python27/lib/python2.7/site-packages/pip-10.0.0b1-py2.7.egg/pip/_vendor/urllib3/util/ssl_.py:339: SNIMissingWarning: An HTTPS request has been made, but the SNI (Subject Name Indication) extension to TLS is not available on this platform. This may cause the server to present an incorrect TLS certificate, which can cause validation failures. You can upgrade to a newer version of Python to solve this. For more information, see https://urllib3.readthedocs.io/en/latest/advanced-usage.html#ssl-warnings
  SNIMissingWarning
  Using cached ansible-2.5.0-py2.py3-none-any.whl
Collecting paramiko (from ansible)
  Using cached paramiko-2.4.1-py2.py3-none-any.whl
Collecting cryptography (from ansible)
  Using cached cryptography-2.2.2-cp27-cp27m-manylinux1_x86_64.whl
Requirement already satisfied: setuptools in /opt/Python27/lib/python2.7/site-packages/setuptools-39.0.1-py2.7.egg (from ansible) (39.0.1)
Collecting PyYAML (from ansible)
  Using cached PyYAML-3.12.tar.gz
Collecting jinja2 (from ansible)
  Using cached Jinja2-2.10-py2.py3-none-any.whl
Collecting pyasn1>=0.1.7 (from paramiko->ansible)
  Using cached pyasn1-0.4.2-py2.py3-none-any.whl
Collecting bcrypt>=3.1.3 (from paramiko->ansible)
  Using cached bcrypt-3.1.4-cp27-cp27m-manylinux1_x86_64.whl
Collecting pynacl>=1.0.1 (from paramiko->ansible)
  Using cached PyNaCl-1.2.1-cp27-cp27m-manylinux1_x86_64.whl
Collecting six>=1.4.1 (from cryptography->ansible)
  Using cached six-1.11.0-py2.py3-none-any.whl
Collecting cffi>=1.7; platform_python_implementation != "PyPy" (from cryptography->ansible)
  Using cached cffi-1.11.5-cp27-cp27m-manylinux1_x86_64.whl
Collecting enum34; python_version < "3" (from cryptography->ansible)
  Using cached enum34-1.1.6-py2-none-any.whl
Collecting asn1crypto>=0.21.0 (from cryptography->ansible)
  Using cached asn1crypto-0.24.0-py2.py3-none-any.whl
Collecting idna>=2.1 (from cryptography->ansible)
  Using cached idna-2.6-py2.py3-none-any.whl
Collecting ipaddress; python_version < "3" (from cryptography->ansible)
  Using cached ipaddress-1.0.19.tar.gz
Collecting MarkupSafe>=0.23 (from jinja2->ansible)
  Using cached MarkupSafe-1.0.tar.gz
Collecting pycparser (from cffi>=1.7; platform_python_implementation != "PyPy"->cryptography->ansible)
  Using cached pycparser-2.18.tar.gz
Installing collected packages: pyasn1, six, pycparser, cffi, bcrypt, enum34, asn1crypto, idna, ipaddress, cryptography, pynacl, paramiko, PyYAML, MarkupSafe, jinja2, ansible
  Running setup.py install for pycparser ... done
  Running setup.py install for ipaddress ... done
  Running setup.py install for PyYAML ... done
  Running setup.py install for MarkupSafe ... done

Successfully installed MarkupSafe-1.0 PyYAML-3.12 ansible-2.5.0 asn1crypto-0.24.0 bcrypt-3.1.4 cffi-1.11.5 cryptography-2.2.2 enum34-1.1.6 idna-2.6 ipaddress-1.0.19 jinja2-2.10 paramiko-2.4.1 pyasn1-0.4.2 pycparser-2.18 pynacl-1.2.1 six-1.11.0

Version

# ansible --version

ansible 2.5.0
  config file = None
  configured module search path = [u'/root/.ansible/plugins/modules', u'/usr/share/ansible/plugins/modules']
  ansible python module location = /opt/Python27/lib/python2.7/site-packages/ansible
  executable location = /opt/Python27/bin/ansible
  python version = 2.7.14 (default, Mar 31 2018, 20:00:21) [GCC 4.1.2 20080704 (Red Hat 4.1.2-55)]

Ansible v2

# ansible -m ping localhost

localhost | SUCCESS => {
    "changed": false,
    "ping": "pong"
}

Ansible v1

or a previous version for testing

eg. 1.9.6

# pip install 'ansible==1.9.6'

# ansible --version

ansible 1.9.6
  configured module search path = None

# yum -y install python-simplejson

# ansible localhost -c local -m ping -i "localhost,"

localhost | success >> {
    "changed": false,
    "ping": "pong"
}

Possible Building Error

When building python from source, setup.py will try to look for /usr/local/ssl/ directory to find the libraries and included headers of openssl. Althouth it works from _ssl.c , it doesnt for _hashlib.c.

To fix this problem, you must manual edit the Python-2.7.14/setup.py

 869                 ssl_incs += ['/usr/local/ssl/include']
 870                 ssl_libs += ['/usr/local/ssl/lib']

the full code is:

 865         if have_any_openssl:
 866             if have_usable_openssl:
 867                 # The _hashlib module wraps optimized implementations
 868                 # of hash functions from the OpenSSL library.
 869                 ssl_incs += ['/usr/local/ssl/include']
 870                 ssl_libs += ['/usr/local/ssl/lib']
 871                 exts.append( Extension('_hashlib', ['_hashopenssl.c'],
 872                                        include_dirs = ssl_incs,
 873                                        library_dirs = ssl_libs,
 874                                        libraries = ['ssl', 'crypto']) )
 875             else:
 876                 print ("warning: openssl 0x%08x is too old for _hashlib" %
 877                        openssl_ver)
 878                 missing.append('_hashlib')

hope that helps!

YAML

YAML is a human friendly data serialization standard, especially for configuration files. Its simple to read and use.

Here is an example:

---
# A list of tasty fruits
fruits:
    - Apple
    - Orange
    - Strawberry
    - Mango

btw the latest version of yaml is: v1.2.

PyYAML

Working with yaml files in python is really easy. The python module: PyYAML must be installed in the system.

In an archlinux box, the system-wide installation of this python package, can be done by typing:

$ sudo pacman -S --noconfirm python-yaml

Python3 - Yaml Example

Save the above yaml example to a file, eg. fruits.yml
Open the Python3 Interpreter and write:

$ python3.6
Python 3.6.4 (default, Jan  5 2018, 02:35:40)
[GCC 7.2.1 20171224] on linux
Type "help", "copyright", "credits" or "license" for more information.

>>> from yaml import load 

>>> print(load(open("fruits.yml")))
{'fruits': ['Apple', 'Orange', 'Strawberry', 'Mango']}
>>>

an alternative way is to write the above commands to a python file:

from yaml import load
print(load(open("fruits.yml")))

and run it from the console:

$ python3 test.py
{'fruits': ['Apple', 'Orange', 'Strawberry', 'Mango']}

Instead of print we can use yaml dump:

eg.

import yaml

yaml.dump(yaml.load(open("fruits.yml")))
'fruits: [Apple, Orange, Strawberry, Mango]n'

The return type of yaml.load is a python dictionary:

type(load(open("fruits.yml")))
<class 'dict'>

Have that in mind.

Jinja2

Jinja2 is a modern and designer-friendly templating language for Python.

As a template engine, we can use jinja2 to build complex markup (or even text) output, really fast and efficient.

Here is an jinja2 template example:

I like these tasty fruits:
* {{ fruit }}

where {{ fruit }} is a variable.
Declaring the fruit variable with some value and the jinja2 template can generate the prefarable output.

python-jinja

In an archlinux box, the system-wide installation of this python package, can be done by typing:

$ sudo pacman -S --noconfirm python-jinja

Python3 - Jinja2 Example

Below is a python3 - jinja2 example:

import jinja2

template = jinja2.Template("""
I like these tasty fruits:
* {{ fruit }}
""")

data = "Apple"
print(template.render(fruit=data))

The output of this example is:

I like these tasty fruits:
* Apple

File Template

Reading the jinja2 template from a template file, is a little more complicated than before. Building the jinja2 enviroment is step one:

env = jinja2.Environment(loader=jinja2.FileSystemLoader("./"))

and Jinja2 is ready to read the template file:

template = env.get_template("t.j2")

The template file: t.j2 is a litle diferrent than before:

I like these tasty fruits:
{% for fruit in fruits -%}
* {{ fruit }}
{% endfor %}

Yaml, Jinja2 and Python3

To render the template a dict of global variables must be passed. And parsing the yaml file the yaml.load returns a dictionary! So everything are in place.

Compine everything together:

from yaml import load
from jinja2 import Environment, FileSystemLoader

mydata = (load(open("fruits.yml")))

env = Environment(loader=FileSystemLoader("./"))
template = env.get_template("t.j2")

print(template.render(mydata))

and the result is:

$ python3 test.py

I like these tasty fruits:
* Apple
* Orange
* Strawberry
* Mango

A few years ago, I migrated from ICS Bind Authoritative Server to PowerDNS Authoritative Server.

Here was my configuration file:

# egrep -v '^$|#' /etc/pdns/pdns.conf 

dname-processing=yes
launch=bind
bind-config=/etc/pdns/named.conf

local-address=MY_IPv4_ADDRESS
local-ipv6=MY_IPv6_ADDRESS

setgid=pdns
setuid=pdns

Α quick reminder, a DNS server is running on tcp/udp port53.

---

I use dnsdist (a highly DNS-, DoS- and abuse-aware loadbalancer) in-front of my pdns-auth, so my configuration file has a small change:

local-address=127.0.0.1
local-port=5353

instead of local-address, local-ipv6

You can also use pdns without dnsdist.

---

My named.conf looks like this:

# cat /etc/pdns/named.conf

zone "balaskas.gr" IN {
    type master;
    file "/etc/pdns/var/balaskas.gr";
};

So in just a few minutes of work, bind was no more.
You can read more on the subject here: Migrating to PowerDNS.

---

Converting from Bind zone files to SQLite3

PowerDNS has many features and many Backends. To use some of these features (like the HTTP API json/rest api for automation, I suggest converting to the sqlite3 backend, especially for personal or SOHO use. The PowerDNS documentation is really simple and straight-forward: SQLite3 backend

Installation

Install the generic sqlite3 backend.
On a CentOS machine type:

# yum -y install pdns-backend-sqlite

Directory

Create the directory in which we will build and store the sqlite database file:

# mkdir -pv /var/lib/pdns

Schema

You can find the initial sqlite3 schema here:

/usr/share/doc/pdns/schema.sqlite3.sql

you can also review the sqlite3 database schema from github

If you cant find the schema.sqlite3.sql file, you can always download it from the web:

# curl -L -o /var/lib/pdns/schema.sqlite3.sql  \
   https://raw.githubusercontent.com/PowerDNS/pdns/master/modules/gsqlite3backend/schema.sqlite3.sql

Create the database

Time to create the database file:

# cat /usr/share/doc/pdns/schema.sqlite3.sql | sqlite3 /var/lib/pdns/pdns.db

Migrating from files

Now the difficult part:

# zone2sql --named-conf=/etc/pdns/named.conf -gsqlite | sqlite3 /var/lib/pdns/pdns.db

100% done
7 domains were fully parsed, containing 89 records

Migrating from files - an alternative way

If you have already switched to the generic sql backend on your powerdns auth setup, then you can use: pdnsutil load-zone command.

# pdnsutil load-zone balaskas.gr /etc/pdns/var/balaskas.gr 

Mar 20 19:35:34 Reading random entropy from '/dev/urandom'
Creating 'balaskas.gr'

Permissions

If you dont want to read error messages like the below:

sqlite needs to write extra files when writing to a db file

give your powerdns user permissions on the directory:

# chown -R pdns:pdns /var/lib/pdns

Configuration

Last thing, make the appropriate changes on the pdns.conf file:

## launch=bind
## bind-config=/etc/pdns/named.conf

launch=gsqlite3
gsqlite3-database=/var/lib/pdns/pdns.db

Reload Service

Restarting powerdns daemon:

# service pdns restart

Restarting PowerDNS authoritative nameserver: stopping and waiting..done
Starting PowerDNS authoritative nameserver: started

Verify

# dig @127.0.0.1 -p 5353  -t soa balaskas.gr +short 

ns14.balaskas.gr. evaggelos.balaskas.gr. 2018020107 14400 7200 1209600 86400

or

# dig @ns14.balaskas.gr. -t soa balaskas.gr +short

ns14.balaskas.gr. evaggelos.balaskas.gr. 2018020107 14400 7200 1209600 86400

perfect!

---

Using the API

Having a database as pdns backend, means that we can use the PowerDNS API.

Enable the API

In the pdns core configuration file: /etc/pdns/pdns.conf enable the API and dont forget to type a key.

api=yes
api-key=0123456789ABCDEF

The API key is used for authorization, by sending it through the http headers.

reload the service.

Testing API

Using curl :

# curl -s -H 'X-API-Key: 0123456789ABCDEF' http://127.0.0.1:8081/api/v1/servers

The output is in json format, so it is prefable to use jq

# curl -s -H 'X-API-Key: 0123456789ABCDEF' http://127.0.0.1:8081/api/v1/servers | jq .

[
  {
    "zones_url": "/api/v1/servers/localhost/zones{/zone}",
    "version": "4.1.1",
    "url": "/api/v1/servers/localhost",
    "type": "Server",
    "id": "localhost",
    "daemon_type": "authoritative",
    "config_url": "/api/v1/servers/localhost/config{/config_setting}"
  }
]

jq can also filter the output:

# curl -s -H 'X-API-Key: 0123456789ABCDEF' http://127.0.0.1:8081/api/v1/servers | jq .[].version
"4.1.1"

Zones

Getting the entire zone from the database and view all the Resource Records - sets:

# curl -s -H 'X-API-Key: 0123456789ABCDEF' http://127.0.0.1:8081/api/v1/servers/localhost/zones/balaskas.gr

or just getting the serial:

# curl -s -H 'X-API-Key: 0123456789ABCDEF' http://127.0.0.1:8081/api/v1/servers/localhost/zones/balaskas.gr | \
  jq .serial

2018020107

or getting the content of SOA type:

# curl -s -H 'X-API-Key: 0123456789ABCDEF' http://127.0.0.1:8081/api/v1/servers/localhost/zones/balaskas.gr | \
  jq '.rrsets[] | select( .type | contains("SOA")).records[].content '

"ns14.balaskas.gr. evaggelos.balaskas.gr. 2018020107 14400 7200 1209600 86400"

Records

Creating or updating records is also trivial.
Create the Resource Record set in json format:

# cat > /tmp/test.text <<EOF
{
    "rrsets": [
        {
            "name": "test.balaskas.gr.",
            "type": "TXT",
            "ttl": 86400,
            "changetype": "REPLACE",
            "records": [
                {
                    "content": ""Test, this is a test ! "",
                    "disabled": false
                }
            ]
        }
    ]
}

EOF

and use the http Patch method to send it through the API:

# curl -s -X PATCH -H 'X-API-Key: 0123456789ABCDEF' --data @/tmp/test.text \
    http://127.0.0.1:8081/api/v1/servers/localhost/zones/balaskas.gr | jq . 

Verify Record

We can use dig internal:

# dig -t TXT test.balaskas.gr @127.0.0.1 -p 5353 +short
"Test, this is a test ! "

querying public dns servers:

$ dig test.balaskas.gr txt +short @8.8.8.8
"Test, this is a test ! "

$ dig test.balaskas.gr txt +short @9.9.9.9
"Test, this is a test ! "

or via the api:

# curl -s -H 'X-API-Key: 0123456789ABCDEF' http://127.0.0.1:8081/api/v1/servers/localhost/zones/balaskas.gr | \
   jq '.rrsets[].records[] | select (.content | contains("test")).content'

""Test, this is a test ! ""

That’s it.