Snapcraft 4.0
27 April 2020

The team behind Snapcraft is pleased to announce the release of Snapcraft 4.0. Among the many updates, fixes and additions it
includes, the following are what we consider its highlights:

  • the core20 base is now supported
  • --use-lxd can now be used with all snap supported architectures
  • improved plugins for core20
  • support for adding external repositories

To try this release, switch to the candidate channel for Snapcraft.

Plugins V2

New plugin infrastructure has been developed to support core20.

This new infrastructure greatly simplifies plugins and delivers another great advantage: “quick rebuilds".

Thanks to core20 plugins being much simpler, so to is the environment setup process, removing most of the perceived magic during Snapcraft builds for parts.

Plugins are now applicable only to Snapcraft’s build step. The pull step, for instance, has become completely owned by Snapcraft and dedicated to managing the source related entries for parts.

The following plugins have been updated to work with core20:

While the list of plugins is not as broad as for core or core18, they offer a strong foundation for the majority of snaps, and the list will grow after this initial release.

The command line related to plugins has gained some additional parameters to specifically reach base relevant information:

  • snapcraft help <plugin-name> [--base <base>]
  • ~snapcraft list-plugins [–base ]

These commands will default to using the base defined in the current Snapcraft project or to the latest supported base (i.e., core20).

Also, plugins now have their properties scoped (i.e.; prefixed with the plugin-name).

autotools

The autotools plugin for core20 works mostly in the same way, with the following exceptions:

  • the plugin checks for the existence of configure in the source. If not found, autoconf --install is executed instead
  • configflags has been renamed to autotools~configure-parameters
  • install-via has been removed

cmake

This plugin works mostly the same, except for the fact that configflags has been renamed to cmake-parameters.

dump

This behaves in the same way for core20 as for core18 or core.

go

The plugin has been revamped for core20. It now only supports projects using go.mod, which means it only supports version of go that support this.

The following are the only configuration parameters available to the plugin when using core20:

  • go-channel
  • go-buildtags

These options are no longer available when using core20:

  • go-importpath
  • go-packages

make

The following parameters will be accepted by the plugin when setting core20 as the base:

  • make-parameters

The following are no longer accepted but should instead be easily managed with override-build:

  • makefile
  • artifacts
  • make-install-var

meson

This plugin works the same in core20 although it has been enhanced for easier rebuilds.

nil

This plugin behaves in the same way for core20 as for core18 or core.

npm

This is a new plugin for core20. It is intended to replace the nodejs plugin, which is only available for core and core18.

The only parameter the plugin now accepts is npm-node-version.

python

The python plugin has been simplified the most for core20 and yet provides the most new functionality. It essentially behaves like a virtual environment, preferring the python interpreter shipped in the core20 base.

By behaving this way, the plugin operates more like how a Python developer would expect, allowing for easier snap customization whilst still using the plugin.

The plugin can use an interpreter if it is added through a comprehensive list of stage-packages (an extension shall be evaluated in the future to provide alternative complete python stacks).

When used with core20, the plugin accepts the following parameters, with the same semantics as the V1 plugin used in core and core18:

  • python-packages
  • requirements
  • python-packages

rust

This is another plugin that has been simplified to reduce the number of parameters when targeting core20 as a base:

  • rust-features same behaviour as for core and core18
  • rust-path, defaulting to the current working directory, but can be set to the relative path of the crate to build when using workspaces

Package Management

This feature adds high-level package-management to snapcraft.yaml, enabling users to configure additional repositories & components.

Specifically, the scope of package-management is for anything affecting the behavior and availability of:

  • build-packages
  • stage-packages
  • build-snaps
  • stage-snaps
  • python-packages

The scope of this spec will focus on the configuration of apt repositories, affecting the availability of build-packages and stage-packages.

To use, simply configure package-repositories in snapcraft.yaml.

Note: snapcraft will log an ‘experimental feature’ warning until the schema is considered stable.

Here are some example configurations:

name: apt-example
base: core18

<snip>

package-repositories:
  - type: apt
    ppa: snappy-dev/snapcraft-daily

  - type: apt
    deb-types: [deb, deb-src]
    components: [main]
    suites: [$SNAPCRAFT_APT_RELEASE]
    key-id: 78E1918602959B9C59103100F1831DDAFC42E99D
    url: http://ppa.launchpad.net/snappy-dev/snapcraft-daily/ubuntu

  - type: apt
    deb-types: [deb, deb-src]
    name: default
    components: [main, multiverse, restricted, universe]
    suites: [$SNAPCRAFT_APT_RELEASE, $SNAPCRAFT_APT_RELEASE-updates]
    key-id: test-key
    url: http://archive.ubuntu.com/ubuntu

Build Environments

The --use-lxd flag has been released from its experimental phase and now supports the same build roots as build.snapcraft.io (or Launchpad), bringing the two environments closer together. With these new images, there is now support for all the snap enabled architectures too.

Progressive Releases

Initial experimental support for progressive releases has landed in Snapcraft. To view any existing progressive release use the status command, as an example:

$ snapcraft status candycane
Track     Arch      Channel    Version    Revision    Progress
latest    all       stable     -          -           -
                    candidate  -          -           -
                    beta       0.6        8           → 20%
                               10         13          → 80%
                    edge       ↑          ↑         -

To perform a progressive release, use the release command with the with the --progressive option. After releasing, the status of the release will be shown.