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Jul
14
2019
kubernetes with minikube - Intro Notes
Posted by ebal at 18:41:19 in blog, planet_ellak, planet_Sysadmin, planet_fsfe

Notes based on Ubuntu 18.04 LTS

My notes for this k8s blog post are based upon an Ubuntu 18.05 LTS KVM Virtual Machine. The idea is to use nested-kvm to run minikube inside a VM, that then minikube will create a kvm node.

minikube builds a local kubernetes cluster on a single node with a set of small resources to run a small kubernetes deployment.

Archlinux –> VM Ubuntu 18.04 LTS runs minikube/kubeclt —> KVM minikube node

 

Pre-requirements

Nested kvm

Host

(archlinux)

$ grep ^NAME /etc/os-release
NAME="Arch Linux"

Check that nested-kvm is already supported:

$ cat /sys/module/kvm_intel/parameters/nested
N

If the output is N (No) then remove & enable kernel module again:

$ sudo modprobe -r kvm_intel
$ sudo modprobe kvm_intel nested=1

Check that nested-kvm is now enabled:

$ cat /sys/module/kvm_intel/parameters/nested
Y

 

Guest

Inside the virtual machine:

$ grep NAME /etc/os-release
NAME="Ubuntu"
PRETTY_NAME="Ubuntu 18.04.2 LTS"
VERSION_CODENAME=bionic
UBUNTU_CODENAME=bionic
$ egrep -o 'vmx|svm|0xc0f' /proc/cpuinfo

vmx
$ kvm-ok
INFO: /dev/kvm exists
KVM acceleration can be used

 

LibVirtd

If the above step fails, try to edit the xml libvirtd configuration file in your host:

# virsh edit ubuntu_18.04

and change cpu mode to passthrough:

from

  <cpu mode='custom' match='exact' check='partial'>
    <model fallback='allow'>Nehalem</model>
  </cpu>

to

  <cpu mode='host-passthrough' check='none'/>

 

Install Virtualization Tools

Inside the VM

 

sudo apt -y install
  qemu-kvm
  bridge-utils
  libvirt-clients
  libvirt-daemon-system

Permissions

We need to be included in the libvirt group

sudo usermod -a -G libvirt $(whoami)
newgrp libvirt

 

kubectl

kubectl is a command line interface for running commands against Kubernetes clusters.

size: ~41M

$ export VERSION=$(curl -sL https://storage.googleapis.com/kubernetes-release/release/stable.txt)
$ curl -LO https://storage.googleapis.com/kubernetes-release/release/$VERSION/bin/linux/amd64/kubectl

$ chmod +x kubectl
$ sudo mv kubectl /usr/local/bin/kubectl

$ kubectl completion bash | sudo tee -a /etc/bash_completion.d/kubectl
$ kubectl version

if you wan to use bash autocompletion without logout/login use this:

source <(kubectl completion bash)

What the json output of kubectl version looks like:

$ kubectl version -o json | jq .
The connection to the server localhost:8080 was refused - did you specify the right host or port?
{
  "clientVersion": {
    "major": "1",
    "minor": "15",
    "gitVersion": "v1.15.0",
    "gitCommit": "e8462b5b5dc2584fdcd18e6bcfe9f1e4d970a529",
    "gitTreeState": "clean",
    "buildDate": "2019-06-19T16:40:16Z",
    "goVersion": "go1.12.5",
    "compiler": "gc",
    "platform": "linux/amd64"
  }
}

Message:

The connection to the server localhost:8080 was refused - did you specify the right host or port?

it’s okay if minikube hasnt started yet.

 

minikube

size: ~40M

$ curl -sLO https://storage.googleapis.com/minikube/releases/latest/minikube-linux-amd64

$ chmod +x minikube-linux-amd64

$ sudo mv minikube-linux-amd64 /usr/local/bin/minikube

$ minikube version
minikube version: v1.2.0

$ minikube update-check
CurrentVersion: v1.2.0
LatestVersion: v1.2.0

$ minikube completion bash | sudo tee -a /etc/bash_completion.d/minikube 

To include bash completion without login/logout:

source $(minikube completion bash)

 

KVM2 driver

We need a driver so that minikube can build a kvm image/node for our kubernetes cluster.

size: ~36M

$ curl -sLO https://storage.googleapis.com/minikube/releases/latest/docker-machine-driver-kvm2

$ chmod +x docker-machine-driver-kvm2

$ mv docker-machine-driver-kvm2 /usr/local/bin/

 

Start minikube

$ minikube start --vm-driver kvm2

* minikube v1.2.0 on linux (amd64)
* Downloading Minikube ISO ...
 129.33 MB / 129.33 MB [============================================] 100.00% 0s
* Creating kvm2 VM (CPUs=2, Memory=2048MB, Disk=20000MB) ...
* Configuring environment for Kubernetes v1.15.0 on Docker 18.09.6
* Downloading kubeadm v1.15.0
* Downloading kubelet v1.15.0
* Pulling images ...
* Launching Kubernetes ...
* Verifying: apiserver proxy etcd scheduler controller dns
* Done! kubectl is now configured to use "minikube"

Check via libvirt, you will find out a new VM, named: minikube

$ virsh list
 Id    Name                           State
----------------------------------------------------
 1     minikube                       running

 

Something gone wrong:

Just delete the VM and configuration directories and start again:

$ minikube delete
$ rm -rf ~/.minikube/ ~/.kube

kubectl version

Now let’s run kubectl version again

$ kubectl version -o json | jq .

{
  "clientVersion": {
    "major": "1",
    "minor": "15",
    "gitVersion": "v1.15.0",
    "gitCommit": "e8462b5b5dc2584fdcd18e6bcfe9f1e4d970a529",
    "gitTreeState": "clean",
    "buildDate": "2019-06-19T16:40:16Z",
    "goVersion": "go1.12.5",
    "compiler": "gc",
    "platform": "linux/amd64"
  },
  "serverVersion": {
    "major": "1",
    "minor": "15",
    "gitVersion": "v1.15.0",
    "gitCommit": "e8462b5b5dc2584fdcd18e6bcfe9f1e4d970a529",
    "gitTreeState": "clean",
    "buildDate": "2019-06-19T16:32:14Z",
    "goVersion": "go1.12.5",
    "compiler": "gc",
    "platform": "linux/amd64"
  }
}

 

Dashboard

Start kubernetes dashboard

$ kubectl proxy --address 0.0.0.0 --accept-hosts '.*'
Starting to serve on [::]:8001

minikube_dashboard.png

 

Tag(s): minikube, kubernetes
    Tag: minikube, kubernetes
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