Release policy¶
Our release policy includes two kinds of releases, short-term releases and long-term support (LTS) releases.
We release every six months, same as Ubuntu, and our LTS releases coincide with Ubuntu’s LTS release cadence.
A note on terminology¶
Throughout this page we talk about product releases: COS (and COS Lite) 1, 2, 3.0, and so on. A product release pins a specific combination of charm revisions and Terraform module versions that we test and support together.
“Track” is a Charmhub concept, and each component charm is versioned independently on Charmhub: Grafana, Loki, Mimir, and the others all have their own tracks that rarely line up with the product release number. Some charms happen to use 3.0 as their track for COS 3.0, but most do not. See the release notes for the exact charm tracks bundled in a given product release.
You may also encounter phrases like “track 3 charms” or “track 3.0 charms” used informally to mean “charms released as part of COS 3.0”, our Ubuntu 26.04-based LTS release. This is a shorthand for the product release, not a reference to any specific Charmhub track.
Correspondingly, track/3.0 in this documentation repository is a git branch that hosts the docs for the COS 3.0 product release, not a Charmhub track.
Releases¶
Short-term releases receive security patches and critical bug fixes for nine months. LTS releases receive standard support for the same window as the Ubuntu base they are built on (see Ubuntu’s release cycle), and extended support with an Ubuntu Pro subscription.
Peripheral charms¶
Peripheral charms, such as Blackbox Exporter, are not bundled in COS or COS Lite, but they follow the same release policy: LTS peripheral charms are supported for the same window as the LTS product release they align with, and short-term peripheral charms follow the nine-month window.
Because peripheral charms are consumed on their own (not through the COS or COS Lite Terraform module), they do not carry a product release number. To pick the right revision, refer to each charm’s Charmhub page for its supported tracks and to the release notes of the product release you are aligning against for the recommended revision.
Charmhub tracks and git branches¶
Charmhub tracks (per charm) are created at the beginning of a cycle; the corresponding git branch is created at the end of a cycle.
For example, during June-September 2025 the charms that make up COS 2 already had their 2-series tracks on Charmhub, but this documentation repository still only had track/1 and main branches on GitHub.