Allow using secretRef for hashicorpVault auth

[dttung2905]

Allow referring to a k8s secret that contain hashicorp Vault token. Similar to AzureKeyVault and AWSSecretManager https://keda.sh/docs/2.15/concepts/authentication/#re-use-credentials-and-delegate-auth-with-triggerauthentication

apiVersion: keda.sh/v1alpha1
kind: TriggerAuthentication
metadata:
  name: {trigger-authentication-name}
  namespace: default # must be same namespace as the ScaledObject
spec:
  podIdentity:
      provider: none | azure-workload | aws | aws-eks | gcp  # Optional. Default: none
      identityId: <identity-id>                                           # Optional. Only used by azure & azure-workload providers.
      roleArn: <role-arn>                                                 # Optional. Only used by aws provider.
      identityOwner: keda|workload                                        # Optional. Only used by aws provider.
  secretTargetRef:                                                        # Optional.
  - parameter: {scaledObject-parameter-name}                              # Required.
    name: {secret-name}                                                   # Required.
    key: {secret-key-name}                                                # Required.
  env:                                                                    # Optional.
  - parameter: {scaledObject-parameter-name}                              # Required.
    name: {env-name}                                                      # Required.
    containerName: {container-name}                                       # Optional. Default: scaleTargetRef.envSourceContainerName of ScaledObject
  hashiCorpVault:                                                         # Optional.
    address: {hashicorp-vault-address}                                    # Required.
    namespace: {hashicorp-vault-namespace}                                # Optional. Default is root namespace. Useful for Vault Enterprise
    authentication: token | kubernetes                                    # Required.
    role: {hashicorp-vault-role}                                          # Optional.
    mount: {hashicorp-vault-mount}                                        # Optional.
    credential:                                                           # Optional.
      token: {hashicorp-vault-token}                                      # Optional.
      serviceAccount: {path-to-service-account-file}                      # Optional.
+     tokenSecret:                                                        # Optional.
+       valueFrom:                                                        # Required.
+         secretKeyRef:                                                   # Required.
+           name: {my-secret}                                             # Required.
+           key: {my-key}                                                 # Required.
    secrets:                                                              # Required.
    - parameter: {scaledObject-parameter-name}                            # Required.
      key: {hashicorp-vault-secret-key-name}                               # Required.
      path: {hashicorp-vault-secret-path}

TODO

• Create new test
• Add Changelog
• Add PR to doc

Checklist

• When introducing a new scaler, I agree with the scaling governance policy
• I have verified that my change is according to the deprecations & breaking changes policy
• Tests have been added
• Changelog has been updated and is aligned with our changelog requirements
• A PR is opened to update the documentation on (repo) (if applicable)
• Commits are signed with Developer Certificate of Origin (DCO - learn more)

Fixes #6026

[semgrep-app]

Semgrep found 8 context-todo findings:

• pkg/scaling/resolver/hashicorpvault_handler_test.go
  • L186 - Triage
  • L326 - Triage
  • L362 - Triage
  • L399 - Triage
  • L417 - Triage
  • L485 - Triage
  • L541 - Triage
  • L620 - Triage

Consider to use well-defined context

_{Ignore this finding from context-todo.}

[semgrep-app]

Consider to use well-defined context

_{Ignore this finding from context-todo.}

[JorTurFer]

I see that you have pushed changes this week, are you still working or I can review it?

[dttung2905]

@JorTurFer I think I'm done. Could you help to review it? So sorry I had a busy Christmas so I'm trying to work on the E2E test as you mentioned in the previous stand up