Bases¶

Snaps declare a base in their snapcraft.yaml file. The base defines the feature set used by Snapcraft, the snapcraft.yaml schema, the environment where the snap is built, and which base snap is used at runtime.

How to use a base¶

The base a snap will use is defined in the snap’s snapcraft.yaml.

To use the core24 base for a snap:

base: core24

How to migrate to a newer base¶

See migrating bases for details on migrating to a newer base.

How to use a deprecated base¶

The latest release of Snapcraft does not support older bases. Prior major Snapcraft releases are supported and can be installed from Snapcraft’s tracks.

See base snaps for a list of which Snapcraft major releases support a particular base.

See Snapcraft and ESM for details on support for deprecated bases.

`core18`¶

To build core18 snaps, install snapcraft 7 from the 7.x track:

snap install snapcraft --channel 7.x

`core`¶

To build core snaps, install snapcraft 4 from the 4.x track:

snap install snapcraft --channel 4.x

The base snap mounts itself as the root filesystem within your snap such that when your application runs, the base’s library paths are searched directly after the paths for your specific snap.

How to develop supported and deprecated bases¶

When developing snaps using supported and deprecated bases at the same time, developers must use different versions of Snapcraft. There are a few options:

Refresh channels¶

Switch between Snapcraft releases by refreshing channels. snapd retains the previously installed snap, so refreshing between two channels should not require re-downloading Snapcraft.

snap refresh snapcraft --channel 7.x
snap refresh snapcraft --channel 8.x

Parallel installs¶

Multiple instances of Snapcraft can be installed via snapd’s experimental parallel install feature. See the Parallel installs documentation for details.

snap install snapcraft snapcraft_7 --channel 7.x
snap install snapcraft snapcraft_8 --channel 8.x
snapcraft_8 pack

Containers¶

Isolated development environments allow using different versions of Snapcraft simultaneously.

Snapcraft rocks are the recommended way to build snaps in a container.

How to bootstrap a base snap¶

The build-base keyword is used to bootstrap and create new bases.

To bootstrap the core26 base snap, use the following snapcraft.yaml snippet:

name: core26
type: base
build-base: core24

This snippet will do the following:

name: core26 sets the snap’s name to core26.
type: base creates a base snap.
build-base: core24 builds the snap inside an Ubuntu 24.04 build environment.
base cannot be set in the snapcraft.yaml file

How to build a kernel snap¶

The build-base keyword is used to build kernel snaps for Ubuntu LTS releases.

To build a kernel snap targeting the Ubuntu 22.04 release, use the following snapcraft.yaml snippet:

name: pc-kernel
type: kernel
build-base: core22