Add redis subchart

[ArmaanT]

This PR:

• adds the ability to use the Bitnami Redis chart as a subchart so that renovate can be configured to use Redis for caching.
• Modifies the CI configuration to be able to handle subcharts
• Adds an additional set of values with redis enabled for ct to lint and run tests on

Closes #113

[viceice]

Do we need to commit the subchart? I think this can be removed from repo.

[viceice]

It needs a github workflow change to add the helm repo for bitnami charts

[ArmaanT]

Do we need to commit the subchart? I think this can be removed from repo.

I think it needs to be committed. If I delete the directory and try to helm install, I get the following error:

Release "renovate" does not exist. Installing it now.
Error: found in Chart.yaml, but missing in charts/ directory: redis

Edit: Actually, I think it may be possible to remove charts/ from the repo so long as helm dependency update is run in CI before chart releaser. Since the lockfile is committed this should be an idempotent command

[JamieMagee]

I was just about to post your edit 😅 We need to add

helm repo add bitnami https://charts.bitnami.com/bitnami
helm dependency build

[viceice]

Can you please try @JamieMagee plan.

[ArmaanT]

Okay, this should be ready for review now. I've updated the original PR description with an explanation of my changes.

I haven't tested the release workflow changes. However, it uses very similar logic to kubeval, so I'm reasonably confident it will work.

[viceice]

@JamieMagee what do you think?

[JamieMagee]

Overall looks good. I just have 2 questions:

1. Is there any other configuration that a user might want to pass through to redis?
2. Is there any way to add the bitnami repo automatically? It's defined in charts/renovate/Chart.yaml and I would hope that helm could read that

[ArmaanT]

1. Users will be able to configure redis using any of the values supported by the bitnami chart. I just added a few defaults that made sense to me. By using the redis.fullname template the chart should be able to handle any custom configuration passed to redis.
2. I don't think so unfortunately. I removed the bitnami repo locally and tried to run helm dependency build but it complains that there's no repository definition for https://charts.bitnami.com/bitnami. Seems like helm only uses the definition to make sure the user has a repo with that URL and can't directly install from it

[JamieMagee]

Thanks for the answers. I had a look into 2 myself, and it appears that repositories are not added automatically due to security concerns.

LGTM