GCP HCP Architecture Context

Architectural Invariants

These constraints apply across all topics. Violations should be flagged in code review.

1. No direct cross-cluster connectivity — All cross-cluster coordination uses asynchronous, indirect mechanisms or GCP-level APIs. Direct TCP/UDP between clusters (Global, Regional, Management) is forbidden. PSC for worker-to-control-plane data-plane is the exception.
2. Regional independence — Each region operates independently with minimal cross-region dependencies. No cross-region network costs or data residency violations.
3. Workload Identity for all authentication — No long-lived service account keys. All operators use WIF to bind Kubernetes SAs to Google SAs.
4. Google Managed Prometheus for observability — Hybrid GMP architecture (self-managed Prometheus + GMP storage). No custom Prometheus deployments.
5. ArgoCD for all deployments — No direct helm install or kubectl apply for production workloads.
6. Terraform for infrastructure — All GCP infrastructure managed via Terraform.

Cross-Repo Map

Quality Standards

• Definition of Done: definition-of-done.md — test coverage >= 85%, PR merge criteria
• Story Template: jira-story-template.md — acceptance criteria format
• Design Decision Template: TEMPLATE.md — required sections and validation checklist

How to Use

1. Identify the relevant topic(s) from the user's task
2. Locate the gcp-hcp repo. If you are already working inside gcp-hcp, use the current directory. Otherwise, ask the user: "Where is your local clone of openshift-online/gcp-hcp? (e.g., ~/go/src/github.com/openshift-online/gcp-hcp)" — use the provided path for all subsequent file reads in this session. If the repo is not cloned locally, use the GitHub links in the topic index above.
3. Read the mapped design decisions and architecture docs using the topic index above
4. Apply constraints and rationale when writing or reviewing code
5. Reference specific design decisions in PR descriptions and commit messages
6. Flag any violations of architectural invariants during code review