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.

Base snaps

There are six supported base snaps:

Name	Description	Latest snapcraft track with support
core24	built from Ubuntu 24.04 LTS	8.x
core22	built from Ubuntu 22.04 LTS	8.x
core20	built from Ubuntu 20.04 LTS	8.x
core18	built from Ubuntu 18.04 ESM	7.x
core	built from Ubuntu 16.04 ESM, not to be confused with core16 (see below)	4.x
bare	an empty base that’s useful with fully statically linked snaps and when testing	8.x

Older releases of core were occasionally referred to as core 16, but core and core16 are two distinct packages.

Warning

core16 is not a supported base. With no stable release, its beta and candidate releases are classed as experimental.

See Snapcraft and ESM for details bases built from ESM releases.

base

The base keyword in a snapcraft.yaml file:

• defines the feature set used by Snapcraft

• the snapcraft.yaml schema

• the environment where the snap is built if build-base is not defined

• and which base snap is used at runtime

base must be defined except for base, snapd, and kernel snaps.

base must be a supported base.

build-base

The build-base keyword defines the environment where the snap will be built.

build-base can only be defined for the following scenarios:

Bare base snaps

build-base must be a supported base when base: bare is defined.

Devel builds

build-base must be devel when base is unstable.

Unstable means that the base snap has not been released to the stable channel.

Snaps with a devel build base must have a grade of devel and cannot be promoted to stable or candidate channels.

Kernel snaps

build-base must be a supported base when type: kernel is defined.

See How to build a kernel snap for details on how to use build-base for kernel snaps.