POC: support for k8s secrets

[ffais]

This is a POC to resolve this issue #323. I tested on my cluster and works fine.
There're some issue with my implementation, for example secret namespace and secret key are hard coded.

If you have suggestion on how load secret namespace and key from the CR let me know.

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 64.40%. Comparing base (61b5c5e) to head (a33dc7c).
Report is 38 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #330      +/-   ##
==========================================
+ Coverage   63.22%   64.40%   +1.17%     
==========================================
  Files           6        6              
  Lines         669      545     -124     
==========================================
- Hits          423      351      -72     
+ Misses        198      144      -54     
- Partials       48       50       +2     

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[nakamasato]

Thank you for your contribution.
Basically LGTM but left tiny comments!

[nakamasato]

Can you also update docs?

[ffais]

Can you also update docs?

I'll work on the documentations in the next days, it will probably also be necessary to update the Helm chart to align it with the documentation.

[morfien101]

Is this going to get merged in?

By supporting k8s secrets you can actually remove the GCP support and hand that over to projects like external secrets. This will make this project simpler and more clear cut.

[nakamasato]

@morfien101 Yeah, I'd love to merge this pr. I'll update the branch to run the CI.

[nakamasato]

@ffais I think we need to grant the get permission of Secret to mysql_controller. Can you add it? Other than that, I think we can merge your pr.

mysql-operator/internal/controller/mysql_controller.go

Lines 49 to 53 in dc9848b

	//+kubebuilder:rbac:groups=mysql.nakamasato.com,resources=mysqls,verbs=get;list;watch;create;update;patch;delete
	//+kubebuilder:rbac:groups=mysql.nakamasato.com,resources=mysqls/status,verbs=get;update;patch
	//+kubebuilder:rbac:groups=mysql.nakamasato.com,resources=mysqls/finalizers,verbs=update
	//+kubebuilder:rbac:groups=mysql.nakamasato.com,resources=mysqlusers,verbs=list;
	//+kubebuilder:rbac:groups=mysql.nakamasato.com,resources=mysqldbs,verbs=list;

[nakamasato]

Thank you for your contribution!
I've updated config/rbac/role.yaml and all CI passed!