LXD - ArchWiki

# LXD

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

Related articles

- Linux Containers

## Setup

### Required software

Install LXC and the lxdAUR 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.

## Basic 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

## Advanced usage

### 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.

#### Example network configuration

Thanks to @jpic, the LXD package now provides some example networking configuration in `/usr/share/lxd/`. To use this configuration run the following commands:

    $ ln -s /usr/share/lxd/dnsmasq-lxd.conf /etc/dnsmasq-lxd.conf
    $ ln -s /usr/share/lxd/systemd/system/dnsmasq@lxd.service /etc/systemd/system/dnsmasq@lxd.service
    $ ln -s /usr/share/lxd/netctl/lxd  /etc/netctl/lxd
    $ ln -s /usr/share/lxd/dbus-1/system.d/dnsmasq-lxd.conf /etc/dbus-1/system.d/dnsmasq-lxd.conf

If you use NetworkManager, also symlink the following file:

    $ ln -s /usr/share/lxd/NetworkManager/dnsmasq.d/lxd.conf /etc/NetworkManager/dnsmasq.d/lxd.conf

Change `parent: lxcbr0` to `parent: lxd`:

    $ lxc profile edit default

Finally, enable and start `dnsmasq@lxd.service` and `netctl@lxd.service`.

If you encounter issue with the provided example configuration, or have suggestions to improve it, please leave a comment on the lxdAUR page.

### Modify processes and files limit

You may want to increase file descriptor limit or max user processes limit, since default file descriptor limit is 1024 on Arch Linux.

Edit the `lxd.service`:

    # systemctl edit lxd.service

    [Service]
    LimitNOFILE=infinity
    LimitNPROC=infinity
    TasksMax=infinity

## 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

### No ipv4 on unprivileged Arch container

This section is being considered for removal.

Reason: As of systemd v239, this issue has been fixed. Updating systemd should fix this issue without the workaround below. (Discuss in Talk:LXD#)

This was tested and validated on LXD v.2.20. The container can not start the `systemd-networkd` service so does not get a valid ipv4 address. A work-around was suggested by Stéphane Graber (Github Issue), execute on the host and restart the container:

    $ lxc profile set default security.syscalls.blacklist "keyctl errno 38"

  stgraber: "The reason is that the networkd systemd unit somehow makes use of the kernel keyring, which doesn't work inside unprivileged containers right now. The line above makes that system call return not-implemented which is enough of a workaround to get things going again."

### 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.

## 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

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