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Feb
01
2018
containers containers containers

systemd

Latest systemd version now contains the systemd-importd daemon .

That means that we can use machinectl to import a tar or a raw image from the internet to use it with the systemd-nspawn command.

so here is an example

machinectl

from my archlinux box:

# cat /etc/arch-release

Arch Linux release

CentOS 7

We can download the tar centos7 docker image from the docker hub registry:

# machinectl pull-tar --verify=no https://github.com/CentOS/sig-cloud-instance-images/raw/79db851f4016c283fb3d30f924031f5a866d51a1/docker/centos-7-docker.tar.xz

...
Created new local image 'centos-7-docker'.
Operation completed successfully.
Exiting.

we can verify that:

# ls -la /var/lib/machines/centos-7-docker

total 28
dr-xr-xr-x 1 root root   158 Jan  7 18:59 .
drwx------ 1 root root   488 Feb  1 21:17 ..
-rw-r--r-- 1 root root 11970 Jan  7 18:59 anaconda-post.log
lrwxrwxrwx 1 root root     7 Jan  7 18:58 bin -> usr/bin
drwxr-xr-x 1 root root     0 Jan  7 18:58 dev
drwxr-xr-x 1 root root  1940 Jan  7 18:59 etc
drwxr-xr-x 1 root root     0 Nov  5  2016 home
lrwxrwxrwx 1 root root     7 Jan  7 18:58 lib -> usr/lib
lrwxrwxrwx 1 root root     9 Jan  7 18:58 lib64 -> usr/lib64
drwxr-xr-x 1 root root     0 Nov  5  2016 media
drwxr-xr-x 1 root root     0 Nov  5  2016 mnt
drwxr-xr-x 1 root root     0 Nov  5  2016 opt
drwxr-xr-x 1 root root     0 Jan  7 18:58 proc
dr-xr-x--- 1 root root   120 Jan  7 18:59 root
drwxr-xr-x 1 root root   104 Jan  7 18:59 run
lrwxrwxrwx 1 root root     8 Jan  7 18:58 sbin -> usr/sbin
drwxr-xr-x 1 root root     0 Nov  5  2016 srv
drwxr-xr-x 1 root root     0 Jan  7 18:58 sys
drwxrwxrwt 1 root root   140 Jan  7 18:59 tmp
drwxr-xr-x 1 root root   106 Jan  7 18:58 usr
drwxr-xr-x 1 root root   160 Jan  7 18:58 var

systemd-nspawn

Now test we can test it:

[root@myhomepc ~]# systemd-nspawn --machine=centos-7-docker

Spawning container centos-7-docker on /var/lib/machines/centos-7-docker.
Press ^] three times within 1s to kill container.

[root@centos-7-docker ~]#
[root@centos-7-docker ~]#
[root@centos-7-docker ~]# cat /etc/redhat-release
CentOS Linux release 7.4.1708 (Core)
[root@centos-7-docker ~]#
[root@centos-7-docker ~]# exit
logout
Container centos-7-docker exited successfully.

and now returning to our system:

[root@myhomepc ~]#
[root@myhomepc ~]#
[root@myhomepc ~]# cat /etc/arch-release
Arch Linux release

Ubuntu 16.04.4 LTS

ubuntu example:

# machinectl pull-tar --verify=no https://github.com/tianon/docker-brew-ubuntu-core/raw/46511cf49ad5d2628f3e8d88e1f8b18699a3ad8f/xenial/ubuntu-xenial-core-cloudimg-amd64-root.tar.gz

# systemd-nspawn --machine=ubuntu-xenial-core-cloudimg-amd64-root
Spawning container ubuntu-xenial-core-cloudimg-amd64-root on /var/lib/machines/ubuntu-xenial-core-cloudimg-amd64-root.
Press ^] three times within 1s to kill container.
Timezone Europe/Athens does not exist in container, not updating container timezone.
root@ubuntu-xenial-core-cloudimg-amd64-root:~# 
root@ubuntu-xenial-core-cloudimg-amd64-root:~# cat /etc/os-release 
NAME="Ubuntu"
VERSION="16.04.4 LTS (Xenial Xerus)"
ID=ubuntu
ID_LIKE=debian
PRETTY_NAME="Ubuntu 16.04.4 LTS"
VERSION_ID="16.04"
HOME_URL="http://www.ubuntu.com/"
SUPPORT_URL="http://help.ubuntu.com/"
BUG_REPORT_URL="http://bugs.launchpad.net/ubuntu/"
VERSION_CODENAME=xenial
UBUNTU_CODENAME=xenial
root@ubuntu-xenial-core-cloudimg-amd64-root:~# exit
logout
Container ubuntu-xenial-core-cloudimg-amd64-root exited successfully.
# cat /etc/os-release 
NAME="Arch Linux"
PRETTY_NAME="Arch Linux"
ID=arch
ID_LIKE=archlinux
ANSI_COLOR="0;36"
HOME_URL="https://www.archlinux.org/"
SUPPORT_URL="https://bbs.archlinux.org/"
BUG_REPORT_URL="https://bugs.archlinux.org/"