Charmcraft 4.1 release notes

8 December 2025

Learn about the new features, changes, and fixes introduced in Charmcraft 4.1.

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 4.1 brings the following new features.

Support for Ubuntu 25.10 and Ubuntu 26.04 LTS bases

Charmcraft 4.1 adds experimental support for the Ubuntu 25.10 and Ubuntu 26.04 LTS bases. The purpose of charms built on the Ubuntu 25.10 interim base is to test changes that will affect the upcoming 26.04 release. As such, minor Charmcraft releases may change how these charms build. See our Interim bases policy for further information.

12-factor app charm HTTP proxy relation

Charms that use a 12-factor app extension can now use the http_proxy relation. The Squid Forward Proxy charm is an example provider. To use this relation in your app, add it to the requires key:

requires:
  http-proxy:
    interface: http_proxy
    optional: true
    limit: 1

The init profiles for 12-factor apps now include this relation.

Support for Spring Boot profiles

Charms that use the Spring Boot framework extension can now configure active Spring Boot profiles at runtime.

Known issues

The following issues were reported and are scheduled to be fixed in upcoming patch releases.

See individual issue links for any mitigations.

  • #2078 charmcraft clean does not clean all platforms for a charm.

  • #1990 Cannot stage packages with Charmcraft

  • #2493 Packing fails when using a separate metadata.yaml file and the --project-dir argument.

  • #2492 Internal error when uploading a charm outside of a project directory.

Contributors

We would like to express a big thank you to all the people who contributed to this release:

@aj4ayushjain, @alithethird, @dwilding, @erinecon, @james-garner-canonical, @jahn-junior, @javierdelapuente, @lengau, @medubelko, @swetha1654 and @tonyandrewmeyer