How to create instances

When creating an instance, you must specify the image on which the instance should be based.

Images contain a basic operating system (for example, a Linux distribution) and some LXD-related information. Images for various operating systems are available on the built-in remote image servers. See Images for more information.

If you don’t specify a name for the instance, LXD will automatically generate one. Instance names must be unique within a LXD deployment (also within a cluster). See Instance name requirements for additional requirements.

To create an instance, you can use either the lxc init or the lxc launch command. The lxc init command only creates the instance, while the lxc launch command creates and starts it.

Enter the following command to create a container:

lxc launch|init <image_server>:<image_name> <instance_name> [flags]

Unless the image is available locally, you must specify the name of the image server and the name of the image (for example, ubuntu:22.04 for the official 22.04 Ubuntu image).

See lxc launch --help or lxc init --help for a full list of flags. The most common flags are:

  • --config to specify a configuration option for the new instance

  • --device to override device options for a device provided through a profile, or to specify an initial configuration for the root disk device

  • --profile to specify a profile to use for the new instance

  • --network or --storage to make the new instance use a specific network or storage pool

  • --target to create the instance on a specific cluster member

  • --vm to create a virtual machine instead of a container

Instead of specifying the instance configuration as flags, you can pass it to the command as a YAML file.

For example, to launch a container with the configuration from config.yaml, enter the following command:

lxc launch ubuntu:22.04 ubuntu-config < config.yaml

Tip

Check the contents of an existing instance configuration (lxc config show <instance_name> --expanded) to see the required syntax of the YAML file.

Examples

The following examples create the instances, but don’t start them. If you are using the CLI client, you can use lxc launch instead of lxc init to automatically start them after creation.

Create a container

To create a container with an Ubuntu 22.04 image from the ubuntu server using the instance name ubuntu-container, enter the following command:

lxc init ubuntu:22.04 ubuntu-container

Create a virtual machine

To create a virtual machine with an Ubuntu 22.04 image from the ubuntu server using the instance name ubuntu-vm, enter the following command:

lxc init ubuntu:22.04 ubuntu-vm --vm

Or with a bigger disk:

lxc init ubuntu:22.04 ubuntu-vm-big --vm --device root,size=30GiB

Create a container with specific configuration options

To create a container and limit its resources to one vCPU and 192 MiB of RAM, enter the following command:

lxc init ubuntu:22.04 ubuntu-limited --config limits.cpu=1 --config limits.memory=192MiB

Create a VM on a specific cluster member

To create a virtual machine on the cluster member server2, enter the following command:

lxc init ubuntu:22.04 ubuntu-vm-server2 --vm --target server2

Create a container with a specific instance type

LXD supports simple instance types for clouds. Those are represented as a string that can be passed at instance creation time.

The syntax allows the three following forms:

  • <instance type>

  • <cloud>:<instance type>

  • c<CPU>-m<RAM in GiB>

For example, the following three instance types are equivalent:

  • t2.micro

  • aws:t2.micro

  • c1-m1

To create a container with this instance type, enter the following command:

lxc init ubuntu:22.04 my-instance --type t2.micro

The list of supported clouds and instance types can be found here:

Create a VM that boots from an ISO

To create a VM that boots from an ISO, you must first create a VM. Let’s assume that we want to create a VM and install it from the ISO image. In this scenario, use the following command to create an empty VM:

lxc init iso-vm --empty --vm

The second step is to import an ISO image that can later be attached to the VM as a storage volume:

lxc storage volume import <pool> <path-to-image.iso> iso-volume --type=iso

Lastly, attach the custom ISO volume to the VM using the following command:

lxc config device add iso-vm iso-volume disk pool=<pool> source=iso-volume boot.priority=10

The boot.priority configuration key ensures that the VM will boot from the ISO first. Start the VM and connect to the console as there might be a menu you need to interact with:

lxc start iso-vm --console

Once you’re done in the serial console, disconnect from the console using Ctrl+a q and connect to the VGA console using the following command:

lxc console iso-vm --type=vga

You should now see the installer. After the installation is done, detach the custom ISO volume:

lxc storage volume detach <pool> iso-volume iso-vm

Now the VM can be rebooted, and it will boot from disk.