[common]: Enable mounting of existing secrets

[wthhub]

What this PR does:

Enable mounting of existing secrets and enable optional flag when mounting an existing ressources.

https://kubernetes.io/docs/concepts/configuration/secret/#restriction-secret-must-exist

Notes for Reviewer:
mostly copied from: #147

Checklist:

• Pull Request title in format [chart]: Changed Something
• Updated documentation in the README.md.gotmpl file and executed helm-docs
• Chart Version bumped
• All commits are signed-off

[fanks4]

Thank you for your pull request @wthhub
Sorry for my late answer. I was a little bit confused about the "existing" flag.
There are a couple of similar functions available. Have you considered whether components.[*].controller.envFrom.secretRef ,components.[*].controller.containers.[*].envFrom.secretRef or components.[*].controller.containers.[*].configFiles fits your usecase?

What do you think abourt the _files.yaml template? I guess it is saver to exclude existing secrets and configMaps somewhere around line 9. Unless .filePath is not set, everything should work anyway.
Sorry, that I did not realize this when I did the review for #147.

I added notices to two more comment lines.

Since I tested both types and optional flag I can confirm that the basic functionally is given with your change.

[wthhub]

Thank you for your pull request @wthhub Sorry for my late answer. I was a little bit confused about the "existing" flag. There are a couple of similar functions available. Have you considered whether components.[*].controller.envFrom.secretRef ,components.[*].controller.containers.[*].envFrom.secretRef or components.[*].controller.containers.[*].configFiles fits your usecase?

What do you think abourt the _files.yaml template? I guess it is saver to exclude existing secrets and configMaps somewhere around line 9. Unless .filePath is not set, everything should work anyway. Sorry, that I did not realize this when I did the review for #147.

I added notices to two more comment lines.

Since I tested both types and optional flag I can confirm that the basic functionally is given with your change.

@fanks4, thanks for your review!

The requirement is that the files can be mounted as files, so the options as environment variables are not applicable.
With the existing configFiles options, only specific formats or Base64 encoded files can be mounted.
However, since we want to offer the possibility to mount all file types readably without overloading the Helm values file, we have decided on this extension. In addition, external secrets can thus be used multiple times.

The filePath attribute has nothing to do with the two PRs. This allows you to create a secret from a file. However, this requires that the file is "local" available. For the intended use case, however, an existing secret should be mountable.

[fanks4]

Thank you for the explanations and your changes @wthhub.
I guess it's acceptable to let the user decide whether a secret should be generated or not.
If not filePath must not be set.

[wthhub]

Thank you for the explanations and your changes @wthhub. I guess it's acceptable to let the user decide whether a secret should be generated or not. If not filePath must not be set.

opened an internal follow up task to clearify this