Generate reva configuration from Helm Values

[mirekys]

This PR allows chart users to modify individual settings of Reva daemon directly either
by Helm values.yaml or by helm upgrade ... --set config.some-reva-setting=value method, rather
than by rewriting the whole revad.toml file. It also allows for inheritance of common Reva settings in subcharts,
leveraging built-in Helm values inheritance.

Currently used way of configuring Reva using static toml files:

configFiles:
  revad.toml: |
    [grpc]
    ...

remains still possible.

Contributing a Chart / update to an existing Chart

• Run helm lint on the chart dir.
• (Update) Bump the Chart.yaml version before merging, to release it as a new version.
• (Update) Replace the annotations on the Chart.yaml with:
  • artifacthub.io/changes - the changes introduced on the PR with the appropiate format.
  • artifacthub.io/images - the updated tag on the cs3org/revad image.
• (Update) If the PR includes new configurable parameters in the chart's values.yaml. Add documentation in the appropiate README.

[SamuAlfageme]

@mirekys very nice idea behind this PR, I love it!

However, I think as both a backwards-compatibility mechanism and to provide some flexibility in terms of being able to inject the .toml file directly (e.g. when migrating from existing non-kubernetes reva installations), it could be good to keep this logic as well as fallback.

For instance, when passing a file rather than individual config parameters - cc/ @labkode we discussed this a couple of years ago, what do you think?

[mirekys]

However, I think as both a backwards-compatibility mechanism and to provide some flexibility in terms of being able to inject the .toml file directly (e.g. when migrating from existing non-kubernetes reva installations), it could be good to keep this logic as well as fallback.

Hi @SamuAlfageme, this change is already backwards-compatible. If someone wishes to inject toml file as a reva config,
he could still do: helm ... --set-file .configFiles.revad\\.toml=custom-gateway.toml .... Doing so completely overrides this template with custom-gateway.toml file contents. In addition, you can also use helm template tags in that toml file (basically in any file under configFiles) and now it gets resolved (here).

[labkode]

@dagl please review

[mirekys]

Any news on this @dagl @labkode? It has some potential to help with simplifying reva site configurations