Incus is a community fork of LXD, a next generation system container and virtual machine manager. Debian packages LTS releases of Incus, beginning with trixie. A backported version of Incus is also available in bookworm-backports.
Contents
Supported versions of Incus
Incus (upstream) has the following releases:
Version |
EOL |
In Debian release |
6.0 LTS |
Trixie (anticipated; as of June 2024, version 6.0.1 is packaged) |
Installation
Installing on Debian is as simple as installing the incus package:
sudo apt install incus
Incus initialization
If you wish to migrate existing containers or VMs from LXD, please refer to the next section. Otherwise, after installing Incus you must perform an initial configuration:
sudo incus admin init
Migrating from LXD
Incus includes a tool named lxd-to-incus which can be used to convert an existing LXD installation into an Incus one.
For this to work properly, you should install Incus but not initialize it. Instead, make sure that both incus info and lxc info both work properly, then run lxd-to-incus to migrate your data.
This process transfers the entire database and all storage from LXD to Incus, resulting in an identical setup after the migration.
For further information, please view the migration HOWTO.
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This should be considered a destructive action from LXD's perspective. Afterwards the LXD daemon may not properly start, and running lxc list will be empty. It is recommend that the LXD packages be purged as part of running lxd-to-incus, or by hand immediately following the migration.
Configuration
Incus's default bridge networking requires the dnsmasq-base package to be installed. If you chose to install Incus without its recommended packages and intend to use the default bridge, you must first install dnsmasq-base for networking to work correctly.
If you wish to allow non-root users to interact with Incus via the local Unix socket, you must add them to the incus group:
sudo usermod -aG incus <username>
Access via the incus group grants restricted access to Incus, allowing members to run most commands, except incus admin. For the vast majority of use cases, this is the preferred setup.
Alternatively, if you wish to allow non-root users full administrative access to Incus via the local Unix socket, you must add them to the incus-admin group:
sudo usermod -aG incus-admin <username>
From the upstream documentation, be aware that local access to Incus through the Unix socket via the incus-admin group always grants full access to Incus. This includes the ability to attach file system paths or devices to any instance as well as tweak the security features on any instance. Therefore, you should only give access to users who would be trusted with root access to the host.
Storage backends
Incus supports several storage backends. When installing, Incus will suggest the necessary packages to enable all storage backends, but in brief:
btrfs requires the btrfs-progs package
ceph/cephfs require the ceph-common package
lvm requires the lvm2 package
zfs requires the zfsutils-linux package
After installing one or more of those additional packages, be sure to restart the Incus service so it picks up the additional storage backend(s).
Virtual machines
Incus optionally can create virtual machine instances utilizing QEMU. To enable this capability, on the host system install the desired qemu-system-<arch> package(s) and the incus-agent package. Then, restart the Incus service. You will now be able to create virtual machine instances by passing the --vm flag in your creation command.
RHEL8/9 (and derivatives)
RHEL8/9 do not ship the 9p kernel module, which is used to dynamically mount instance-specific agent configuration and the incus-agent binary into VMs. To work around this, Incus 0.5.1 added a new agent drive, providing those files through what looks like a CD-ROM drive rather than being retrieved over a networked filesystem.
For example, to run CentOS 9-Stream, one now needs to do:
incus create images:centos/9-Stream centos --vm incus config device add centos agent disk source=agent:config incus start centos
For further details, please see the Incus 0.5.1 release notes.
Known issues
Versions of Incus prior to 0.5 had a bug in the idmap parser that was causing everything but the first large entry for the root user to be discarded when parsing /etc/subuid and /etc/subgid. If containers fail to start with the error newuidmap failed to write mapping "newuidmap: write to uid_map failed: Invalid argument", review the upgrade notes section of the Incus 0.5 release notes for instructions on how to fix this.
- Running Incus and Docker on the same host can cause connectivity issues. A common reason for these issues is that Docker sets the FORWARD policy to DROP, which prevents Incus from forwarding traffic and thus causes the instances to lose network connectivity. There are two different ways you can fix this:
As outlined in bug 865975, message 91, you can add net.ipv4.ip_forward=1 to /etc/sysctl.conf which will create a FORWARD policy that docker can use. Docker then won't set the FORWARD chain to DROP when it starts up.
Alternately, you can use the following command to explicitly allow network traffic from your network bridge to your external network interface: iptables -I DOCKER-USER -i <network_bridge> -o <external_interface> -j ACCEPT (from the upstream Incus documentation)
If the apparmor package is not installed on the host system, containers will fail to start unless their configuration is modified to include lxc.apparmor.profile=unconfined; this has been reported upstream at https://github.com/lxc/lxc/issues/4150.
References