How to create images

If you want to create and share your own images, you can do this either based on an existing instance or snapshot or by building your own image from scratch.

Publish an image from an instance or snapshot

If you want to be able to use an instance or an instance snapshot as the base for new instances, you should create and publish an image from it.

To publish an image from an instance, make sure that the instance is stopped. Then enter the following command:

lxc publish <instance_name> [<remote>:]

To publish an image from a snapshot, enter the following command:

lxc publish <instance_name>/<snapshot_name> [<remote>:]

In both cases, you can specify an alias for the new image with the --alias flag, set an expiration date with --expire and make the image publicly available with --public. See lxc publish --help for a full list of available flags.

The publishing process can take quite a while because it generates a tarball from the instance or snapshot and then compresses it. As this can be particularly I/O and CPU intensive, publish operations are serialized by LXD.

Prepare the instance for publishing

Before you publish an image from an instance, clean up all data that should not be included in the image. Usually, this includes the following data:

  • Instance metadata (use lxc config metadata to edit)

  • File templates (use lxc config template to edit)

  • Instance-specific data inside the instance itself (for example, host SSH keys and dbus/systemd machine-id)

Build an image

For building your own images, you can use LXD image builder.

See the LXD image builder documentation for instructions for installing and using the tool.