Add release steps to serve Helm Charts Repository on Github Pages

[akozich]

Currently Helm Charts are attached to Github Release. It's enough to install chart as is.

In our case we had to extend it with our deployment specific resources. The most correct way was to make our own chart having kafka-lag-exporter as a dependency. But in order to specify a dependency chart must he stored in Helm Charts Repository.

In this PR I've added few steps to serve Helm Charts Repository on Github Pages as explained here https://helm.sh/docs/topics/chart_repository/.

Changes summary:

1. store chart to a separate folder instead of project root
2. Try to download existing charts index
3. Use helm index providing existing index to build a new repository index
4. Create github pages branch if it does not exist on github
5. Fetch github pages branch into separate git worktree
6. Copy new repository index to the new worktree
7. Commit worktree
8. Remove worktree

[lightbend-cla-validator]

At least one pull request committer is not linked to a user. See https://help.github.com/en/articles/why-are-my-commits-linked-to-the-wrong-user#commits-are-not-linked-to-any-user

[lightbend-cla-validator]

Hi @akozich,

Thank you for your contribution! We really value the time you've taken to put this together.

Before we proceed with reviewing this pull request, please sign the Lightbend Contributors License Agreement:

https://www.lightbend.com/contribute/cla

[seglo]

LGTM. Thanks. I'll test this out in a release later this week.

[seglo]

Hey @akozich . I ran this as part of the 0.6.6 release, but it doesn't seem to add or push the chart repo artifacts in the gh-pages branch. I see a .helm-release-packages dir, but it's not tracked. How did you intend this to work? Maybe we can create a chart-repo dir in the gh-pages branch and commit changes to that?

[seglo]

I'll study this more later. In the meantime I manually published the chart repo here: http://lightbend.github.io/kafka-lag-exporter/repo/index.yaml

[akozich]

Hey @seglo . .helm-release-packages directory is not supposed to be indexed. It consists intermediate results. My scripts had to create gh-pages branch where the only committed file will be index.yaml.

[akozich]

As I can see gh-pages branch was created but for some reason it has all files from master. That's strange.

[seglo]

I created it manually when I didn't see it after the release.

[seglo]

I'll play around with it before the next release. Was it intended for the repo index.yaml to be a the root of the project?

http://lightbend.github.io/kafka-lag-exporter/index.yaml