Document purpose of dev-python images

[bc3tech]

The python dc images also have a dev-python variant that is largely undocumented as to its purpose & content. This should be documented so developers know the difference and can decide what may be best suited for their purposes.

[Kaniska244]

Hello @bc3tech ,

The dev container images with "dev" tag published each week are more of the preview images. Please find below some details on the same. Kindly let me know in case of further concern/ information.

What are "dev" images:

• “dev” images are rolling builds produced from the main branch for each image (e.g., go, cpp, dotnet, ruby). They serve as preview builds that incorporate the latest upstream OS packages, language/tool updates, and repository changes before a formal versioned release.

• Tags typically include both a plain dev tag and dev variants by language/runtime and distro, for example:
  mcr.microsoft.com/devcontainers/go:dev, mcr.microsoft.com/devcontainers/go:dev-1.25, mcr.microsoft.com/devcontainers/go:dev-trixie
  mcr.microsoft.com/devcontainers/cpp:dev, mcr.microsoft.com/devcontainers/cpp:dev-trixie
  When they’re published each week

Update policy and guidance:

• Dev tags are intentionally “rolling”: they get rebuilt and retagged weekly. The release tool notes that the “replace-images” option does not apply to dev tags, reinforcing their non-versioned, constantly updated nature.

• Use dev tags to test upcoming changes; for reproducible environments, prefer versioned tags and partial versions (major or major.minor) to pick up only non-breaking changes or fixes.

• Use dev to get ahead of updates, and use versioned tags when you need predictable builds.

[bc3tech]

That's great - is it documented somewhere other than this issue?

[Kaniska244]

Indeed the "dev" tag behavior doesn't appear to be documented in details as far as I can see. We will check on the possibility of documenting the behavior of "dev" images.