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How to start a container with systemd-nspawn?
systemd-nspawn is used to directly start a container. By default, it just spawns a root shell inside the container’s environment. Using the -b switch will instead boot the container and afterwards give you a login shell. However, as soon as the command terminates, the container shuts down as well.
Is it necessary to override default settings in systemd-nspawn?
Settings files override the default options used by the [email protected] template unit file, making it usually unnecessary to alter this template file directly. Note that systemd-nspawn will mount file systems private to the container to /dev/, /run/ and similar.
Are there any isolated resources in systemd nspawn?
As we’ve said, systemd-nspawn resources are not isolated. Using systemctl, limits can be set on the resources a container can consume, for example: Limits on the resources containers can access may be recorded in the unit file or [Slice] section. Systemd-nspawn is an interesting and prospective tool.
When to use systemd nspawn vs chroot ( 1 )?
In contrast to chroot (1) systemd-nspawn may be used to boot full Linux-based operating systems in a container. systemd-nspawn limits access to various kernel interfaces in the container to read-only, such as /sys/, /proc/sys/ or /sys/fs/selinux/. The host’s network interfaces and the system clock may not be changed from within the container.
Where to find service template in systemd nspawn?
The service template file is located at /lib/systemd/system/[email protected]. It is worth it to take a look inside, especially the specified executable: As you can see, there are already quite a few command line arguments specified by default when you use machinectl to start a container.
Which is more powerful chroot or systemd nspawn?
systemd-nspawn is like the chroot command, but it is a chroot on steroids. systemd-nspawn may be used to run a command or OS in a light-weight namespace container. It is more powerful than chroot since it fully virtualizes the file system hierarchy, as well as the process tree, the various IPC subsystems and the host and domain name.
How to start and stop a container in systemd?
Finally, with the -M machine_name switch, you specify the container to launch. machinectl is very similar to systemd’s systemctl, but is used specifically to work with containers. In fact, containers can be started, stopped and enabled just like any other systemd service.
How to switch off binding to port 53 in systemd?
As of systemd 232 (released in 2017) you can edit /etc/systemd/resolved.conf and add this line: This will switch off binding to port 53. The option is described in more details in the resolved.conf manpage.
How to set up a container in systemd?
First, we need to set up an OS tree in an empty directory, which will serve as the container’s root directory. To achieve this, we will use debootstrap. systemd expects containers to be located inside the /var/lib/machines directory. They can be elsewhere, but then some tools won’t automatically recognize the container.
What are the main features of systemd-nspawn?
We’ve already looked at the main features of systemd-nspawn. There’s only one key element left: dedicated container resources. As we’ve said, systemd-nspawn resources are not isolated. Using systemctl, limits can be set on the resources a container can consume, for example:
How to set up a container in Debian?
Let’s install them first: debootstrap installs a minimal Debian system into a custom directory. systemd-container contains the systemd tools to run and configure containers. bridge-utils allows for easy setup of a bridge to give the container network access.