How to create instances

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.

Usage

Enter the following command to create a container:

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

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.

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).

Instance name

Instance names must be unique within a LXD deployment (also within a cluster). See Instance properties for additional requirements.

Flags

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

  • --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

Pass a configuration file

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 use lxc launch, but you can use lxc init in the same way.

Launch a container

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

lxc launch ubuntu:22.04 ubuntu-container

Launch a virtual machine

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

lxc launch ubuntu:22.04 ubuntu-vm --vm

Or with a bigger disk:

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

Launch a container with specific configuration options

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

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

Launch a VM on a specific cluster member

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

lxc launch ubuntu:22.04 ubuntu-container --vm --target server2

Launch 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 launch a container with this instance type, enter the following command:

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

The list of supported clouds and instance types can be found at https://github.com/dustinkirkland/instance-type.

Launch a VM that boots from an ISO

To launch 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 <path-to-image.iso> iso-volume --type=iso

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

lxc config device add iso-vm iso-volume disk pool=default 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, you need to 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, you need to detach the custom ISO volume:

lxc storage volume detach default iso-volume iso-vm

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