infra/gcp/prod-storage: fix ensure-prod-storage.sh

[spiffxp]

This is part of #1730 and an attempt to unblock deploying #1966 (comment)

The first two commits are mechnical refactoring that was easy enough to do while here:

• pull blocks of related code into functions, add a main function, call the functions in main
• fix shellcheck nits my editor was displaying to me

The actual surgical fix is the third commit:

• ensure the auditor service accounts are created before trying to create an IAM policy binding on them

I would like to redo the logic in this script to be less hidden in lib.sh but will save that for a future PR

[k8s-ci-robot]

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[spiffxp]

/cc @hh @ameukam @dims
Since you were involved in the PR this is intended to unblock

[ameukam]

/lgtm
/hold
hold cancel when you're ready to deploy.

[spiffxp]

/hold cancel

[spiffxp]

Ran ./infra/gcp/ensure-prod-storage.sh

The relevant changes as a result of this PR are:

Empowering artifact auditor
  Created service account [k8s-infra-gcr-auditor].
  Updated IAM policy for project [k8s-artifacts-prod].
  @@ -16,6 +16,8 @@
     role: roles/editor
   - member: serviceAccount:k8s-infra-gcr-auditor-invoker@k8s-artifacts-prod.iam.gserviceaccount.com
     role: roles/run.invoker
  +- member: serviceAccount:k8s-infra-gcr-auditor@k8s-artifacts-prod.iam.gserviceaccount.com
  +  role: roles/logging.logWriter
   - member: serviceAccount:k8s-infra-gcr-vuln-dashboard@k8s-artifacts-prod.iam.gserviceaccount.com
     role: roles/containeranalysis.occurrences.viewer
   - member: serviceAccount:service-388270116193@compute-system.iam.gserviceaccount.com
  Updated IAM policy for project [k8s-artifacts-prod].
  @@ -16,6 +16,8 @@
     role: roles/editor
   - member: serviceAccount:k8s-infra-gcr-auditor-invoker@k8s-artifacts-prod.iam.gserviceaccount.com
     role: roles/run.invoker
  +- member: serviceAccount:k8s-infra-gcr-auditor@k8s-artifacts-prod.iam.gserviceaccount.com
  +  role: roles/errorreporting.writer
   - member: serviceAccount:k8s-infra-gcr-auditor@k8s-artifacts-prod.iam.gserviceaccount.com
     role: roles/logging.logWriter
   - member: serviceAccount:k8s-infra-gcr-vuln-dashboard@k8s-artifacts-prod.iam.gserviceaccount.com
  Updated IAM policy for service [cip-auditor].
  bindings:
  - members:
    - serviceAccount:k8s-infra-gcr-auditor-invoker@k8s-artifacts-prod.iam.gserviceaccount.com
    role: roles/run.invoker
  etag: BwXBh4-2Bag=
  version: 1
  Empowering artifact-admins to release prod auditor
  Updated IAM policy for serviceAccount [k8s-infra-gcr-auditor@k8s-artifacts-prod.iam.gserviceaccount.com].
  bindings:
  - members:
    - group:k8s-infra-artifact-admins@kubernetes.io
    role: roles/iam.serviceAccountUser
  etag: BwXBh5ADynw=
  version: 1

This run also picked up changes from #1966

  @@ -6,6 +6,8 @@
     role: roles/storage.legacyBucketOwner
   - member: group:k8s-infra-artifact-admins@kubernetes.io
     role: roles/storage.objectAdmin
  +- member: group:k8s-infra-gcs-access-logs@kubernetes.io
  +  role: roles/storage.objectViewer
   - member: projectEditor:k8s-artifacts-prod
     role: roles/storage.legacyBucketOwner
   - member: projectEditor:k8s-artifacts-prod

[spiffxp]

Related to refactoring infra/gcp, ref: #516