Charmcraft 4.2 release notes¶
17 March 2026
Learn about the new features, changes, and fixes introduced in Charmcraft 4.2.
Requirements and compatibility¶
For development and testing, Charmcraft requires a host with a minimum of 4GB RAM running a Linux distribution compatible with systemd.
All versions of Charmcraft require the following software:
We recommend you install the Charmcraft snap. It comes bundled with all its dependencies.
Non-snap installations of Charmcraft have the following dependencies:
What’s new¶
Charmcraft 4.2 brings the following new features.
Init template updates¶
Charmcraft 4.2 sets Ubuntu 24.04 as the default base for new charms using the machine, kubernetes, django-framework and flask-framework init templates.
The machine and kubernetes templates also now assume Juju 3.6 or newer.
Faster startup for new charms or after cleaning¶
When installed as a snap, Charmcraft now also injects the core24 snap into the created container from the host machine, speeding up initial builds and reducing the download time.
Compiled bytecode from the uv plugin¶
The uv plugin now compiles bytecode for installed Python files
by default. To disable this for your charm, set UV_COMPILE_BYTECODE: false in
the part’s build-environment key.
Updated documentation system¶
The documentation base is updated to Canonical’s Sphinx Starter Pack 1.5. Going forward, the system will stay in step with the Starter Pack, keeping pace with its features.
The documentation commands that are standard in Canonical products are accessible by
prefixing them with docs-:
Command |
Result |
|---|---|
|
Renders the docs as a static set of HTML pages. |
|
Hosts the docs in a local server you can view in the web browser. When you save a change to a source file, the server updates the doc in real time. |
|
Checks for problems in the documentation. |
|
Removes the built docs and temporary files. |
|
See the full list of commands from the Starter Pack. |
Documentation improvements¶
Across the documentation, we made numerous technical corrections, fixed many links, and revised the formatting. We also added:
Known issues¶
The following issues were reported and are scheduled to be fixed in upcoming patch releases.
See individual issue links for any mitigations.
Contributors¶
We would like to express a big thank you to all the people who contributed to this release:
@activus-d,
@alithethird,
@arturo-seijas,
@bepri,
@dwilding,
@f-atwi,
@jahn-junior,
@james-garner-canonical,
@javierdelapuente,
@jonathan-conder,
@lengau,
@medubelko,
@mr-cal,
@smethnani,
@tigarmo,
@tonyandrewmeyer,
and @zhijie-yang