LXD - ArchWiki

# LXD

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LXD is a container and virtual-machine "hypervisor" and a new user experience for Linux Containers.

Related articles

- Linux Containers

## Setup

### Required software

Install LXC and the lxd package, then start `lxd.service`.

See Linux Containers#Enable support to run unprivileged containers (optional) if you want to run unprivileged containers. Otherwise see #Launching container without CONFIG_USER_NS.

### Alternative installation method

An alternative method of installation is via snapd, by installing the snapdAUR package and running:

    # snap install lxd

### Configure LXD

LXD needs to configure a storage pool, and (if you want internet access) network configuration. To do so, run the following as root:

    # lxd init

### Accessing LXD as a unprivileged user

By default the LXD daemon allows users in the `lxd` group access, so add your user to the group:

    # usermod -a -G lxd <user>

Warning: Anyone added to the `lxd` group is root equivalent. More information here and here.

## Usage

### Create container

LXD has two parts, the daemon (the lxd binary), and the client (the lxc binary). Now that the daemon is all configured and running, you can create a container:

    $ lxc launch ubuntu:16.04

Alternatively, you can also use a remote LXD host as a source of images. One comes pre-configured in LXD, called "images" (images.linuxcontainers.org)

    $ lxc launch images:centos/7/amd64 centos

To create an amd64 Arch container:

    $ lxc launch images:archlinux/current/amd64 arch

### LXD Networking

LXD uses LXC's networking capabilities. By default it connects containers to the `lxcbr0` network device. Refer to the LXC documentation on network configuration to set up a bridge for your containers.

If you want to use a different interface than `lxcbr0` edit the default using the lxc command line tool:

    $ lxc profile edit default

An editor will open with a config file that by default contains:

    name: default
    config: {}
    devices:
      eth0:
        name: eth0
        nictype: bridged
        parent: lxcbr0
        type: nic

You can set the `parent` parameter to whichever bridge you want LXD to attach the containers to by default.

### lxd-agent inside VM

Inside VMs `lxd-agent` is not installed by default on the OS. This can be installed on the host by mounting a `9p` network share. This requires console access with a valid user.

       $ lxc console v1
       To detach from the console, press: <ctrl>+a q

       Ubuntu 18.04.3 LTS v1 ttyS0

       v1 login: ubuntu
       Password:
       Welcome to Ubuntu 18.04.3 LTS (GNU/Linux 4.15.0-74-generic x86_64)

       ubuntu@v1:~$ sudo -i
       root@v1:~# mount -t 9p config /mnt/
       root@v1:~# cd /mnt/
       root@v1:/mnt# ./install.sh
       Created symlink /etc/systemd/system/multi-user.target.wants/lxd-agent.service → /lib/systemd/system/lxd-agent.service.
       Created symlink /etc/systemd/system/multi-user.target.wants/lxd-agent-9p.service → /lib/systemd/system/lxd-agent-9p.service.

       LXD agent has been installed, reboot to confirm setup.
       To start it now, unmount this filesystem and run: systemctl start lxd-agent-9p lxd-agent
       root@v1:/mnt# reboot

Afterwards the `lxd-agent` is available and `lxc exec` works inside the VM.

## Troubleshooting

### Check kernel config

By default Arch Linux kernel is compiled correctly for Linux Containers and its frontend LXD. However, if you're using a custom kernel, or changed kernel options the kernel might be configured incorrectly. Verify that the running kernel is properly configured to run a container:

    $ lxc-checkconfig

### Launching container without CONFIG_USER_NS

For launching images you must provide `security.privileged=true` during image creation:

    $ lxc launch ubuntu:16.04 ubuntu -c security.privileged=true

Or for already existed image you may edit config:

    $ lxc config edit ubuntu

    name: ubuntu
    profiles:
    - default
    config:
      ...
      security.privileged: "true"
      ...
    devices:
      root:
        path: /
        type: disk
    ephemeral: false

Or to enable `security.privileged=true` for new containers, edit the config for the default profile:

    $ lxc profile edit default

### Resource limits are not applied when viewed from inside a container

The service lxcfs (found in the Community repository) needs to be installed and started :

    $ systemctl start lxcfs

lxd will need to be restarted. Enable lxcfs for the service to be started at boot time.

### Starting a VM fails

Arch Linux does not distribute secure boot signed ovmf firmware, to boot VMs you need to disable secure boot for the time being.

    $ lxc launch ubuntu:18.04 test-vm --vm -c security.secureboot=false

This can also be added to the default profile.

### No IPv4 with systemd-networkd

Starting with version version 244.1, systemd detects if `/sys` is writable by containers. If it is, udev is automatically started and breaks IPv4 in unprivileged containers. See commit bf331d8 and discussion on linuxcontainers.

On containers created past 2020, there should already be a `systemd.networkd.service` override to work around this issue, create it if it is not:

    /etc/systemd/system/systemd-networkd.service.d/lxc.conf

    [Service]
    BindReadOnlyPaths=/sys

You could also work around this issue by setting `raw.lxc: lxc.mount.auto = proc:rw sys:ro` in the profile of the container to ensure `/sys` is read-only for the entire container, although this may be problematic, as per the linked discussion above.

## Uninstall

Stop and disable `lxd.service` and `lxd.socket`:

Then uninstall the package via pacman:

     # pacman -R lxd

If you uninstalled the package without disabling the service, you might have a lingering broken symlink at `/etc/systemd/system/multi-user.wants/lxd.service`.

If you want to remove all data:

     # rm -r /var/lib/lxd

If you used any of the example networking configs, you should remove those as well.

## See also

- Official documentation
- The official LXD homepage
- The LXD GitHub page

Category:

- Virtualization