Allow existing secret

[ramondeklein]

Allow specifying s.tenant.configSecret.existingSecret in the Helm chart to prevent creating a new certificate.

Fixes #2297 and #2298.

[aqeelat]

When would this be released?

[nepomucen]

@ramondeklein don't we need by chance to comment out tenant.configSecret.accessKey and tenant.configSecret.secretKey fields too in chart's default values.yaml file ?

When I upgrade my minio-tenant release to 6.0.4 version, with en existing values:

...
tenant:
  configSecret:
    existingSecret: true
...

I'm failing validation:

Error: execution error at (tenant/templates/tenant-configuration.yaml:21:4): # ERROR: cannot set access-key when an existing secret is used
  Use --debug flag to render out invalid YAML

Setting these fields explicitly to empty values solves the problem.

[DeyvsonL]

Could we take the opportunity to allow the helm to generate random user and password when not provided?
Several other open source tools allow it and helm implementation of this feature is quite simple.

[shubin-iv]

Because of these checks, you have to set the accessKey and secretKey values ​​to zero when you enable existingSecret, since they already set in main values.
Perhaps it would be better to remove these checks?

[drew-viles]

#2352

Yup, I've got a PR to try and fix this but it's been sat since October 😬