Fix: legacy backend state reading and GC

[chivalryq]

For now if restart controller with --controller-namespace. The configuration state will become GeneratingTerraformOutputs and stuck. This is because controller can't got the legacy backend.

Fix that Configuration.Spec.Backend will be overwritten if set --controller-namespace. Instead, now controller
only overwrite Configuration.Spec.Backend when no backend specified.

How is this tested

Add both unittest and e2e test

Signed-off-by: Qiaozp qiaozhongpei.qzp@alibaba-inc.com

[codecov]

Codecov Report

Merging #338 (a7ece49) into master (5d81c7b) will increase coverage by 3.03%.
The diff coverage is 83.58%.

❗ Current head a7ece49 differs from pull request most recent head 244602c. Consider uploading reports for the commit 244602c to get more accurate results

@@            Coverage Diff             @@
##           master     #338      +/-   ##
==========================================
+ Coverage   76.58%   79.62%   +3.03%     
==========================================
  Files          24       23       -1     
  Lines        1764     1737      -27     
==========================================
+ Hits         1351     1383      +32     
+ Misses        335      272      -63     
- Partials       78       82       +4     

Flag	Coverage Δ
e2e	∅ <ø> (∅)
unit	79.62% <83.58%> (-0.23%)	⬇️

Flags with carried forward coverage won't be shown. Click here to find out more.

Impacted Files	Coverage Δ
controllers/configuration/configuration.go	95.40% <ø> (+2.33%)	⬆️
controllers/configuration/backend/kubernetes.go	77.47% <75.47%> (-5.14%)	⬇️
controllers/configuration_controller.go	77.75% <87.14%> (+0.03%)	⬆️
controllers/configuration/backend/backend.go	89.58% <100.00%> (+0.22%)	⬆️
controllers/provider/credentials.go	92.63% <100.00%> (ø)
controllers/provider/ucloud.go	100.00% <100.00%> (ø)
controllers/terraform/status.go	77.41% <100.00%> (ø)
e2e/normal/regression.go

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[loheagn]

If a user applies a Configuration without spec.Backend, then the terraform apply job will use the default kubernetes backend whose secret is {Namespace: ${env.TERRAFORM_BACKEND_NAMESPACE} || ${configuration.Namespace}, Name: tfstate-default-${confguration.Name}}.

Then, the user restarts the controller with --controller-namespace. In this case, the terraform apply job will use the default kubernetes backend whose secret is {Namespace: ${env.TERRAFORM_BACKEND_NAMESPACE} || ${configuration.Namespace}, Name: tfstate-default-${confguration.UID}}.

The two backend secrets are in the same namespace but have different names. Will this cause an error?

[loheagn]

Shoule we add some e2e tests for the "restart controller with --controller-namespace" cases?

[chivalryq]

If a user applies a Configuration without spec.Backend, then the terraform apply job will use the default kubernetes backend whose secret is {Namespace: ${env.TERRAFORM_BACKEND_NAMESPACE} || ${configuration.Namespace}, Name: tfstate-default-${confguration.Name}}.

Then, the user restarts the controller with --controller-namespace. In this case, the terraform apply job will use the default kubernetes backend whose secret is {Namespace: ${env.TERRAFORM_BACKEND_NAMESPACE} || ${configuration.Namespace}, Name: tfstate-default-${confguration.UID}}.

The two backend secrets are in the same namespace but have different names. Will this cause an error?

There are duplications. But it's OK.

1. New secret won't be used. It is created for simplicity (No need for extra logic).
2. They will be both deleted when calling backend.Cleanup.