Enhance Changelog Detection

[dduportal]

I would want to start a discussion to gather needs and ideas around "changelog" in the context of updatecli.

Today (updatecli v0.95.0), changelog are fully managed if the source is a githubrelease, and partially supported on other cases.

As described by @olblak in https://github.com/orgs/updatecli/discussions/1895#discussioncomment-8267200, the pull requests can be set up, using their description field to templatize an URL pointing to the changelog using the source as an input value.

The following elements needs discussion and brainstorming (are they needed? Are they feasible ? How to make it a good UX ? etc.)

1. "Delta" changelogs: it happens quite often to have a PR covering multiple versions. Usually because the team in charge of merging is busy, or when the rate of updates is faster than the rate of review/deploy (datadog helm chart is a good example).
2. "Simple source-unrelated" changelogs: Quite often, the changelog is not related to the source kind. For instance an Helm chart changelog is stored in a website (ArtifactHub, Github rendered Readme). Example in https://github.com/orgs/updatecli/discussions/1895#discussion-6139236, datadog helm chart is also a good example.
3. "Complex/Composite changelogs": in some cases, a given manifest requires multiple sources which all carry over a changelog element. Users would want to combine/override the changelogs

[dduportal]

A few examples of changelog not really supported by updatecli out of the box (e.g. we could templatize the PR body but the effort and maintenance cost required to do so is not worth it compared to a native support):

• Datadog Helm Chart: Bump datadog helm chart version to 3.105.0 jenkins-infra/kubernetes-management#6302 (review)
  • Good candidates for 1. (delta) and 2. (simple but unrelated source kind)
  • The source is a Helm Chart
  • But the changelog of a given version is a website (GitHub rendered markdown)
  • Nice to have: if the rendered markdown or the source markdown can be inserted into the PR, it would be a cool addon but not mandatory at all
• AWS CLI: Bump aws-cli version to 2.24.24 jenkins-infra/jenkins-infra#3949
  • Good candidates forall points: 1. (delta), 2. (simple but unrelated source kind) and 3. (complex/composite source)