gcp_solution_architecture_agent/docs/requirements-spec.md

Step 0 — approved requirements specification

Workflow request

Produce a reviewable, deployable Google Cloud reference architecture for an event-driven order-ingestion service, while separating product-neutral discovery from product selection and validating IaC without provisioning.

Functional requirements

• Accept authenticated order submissions over HTTPS.
• Validate order payloads and return a synchronous acknowledgement.
• Process accepted orders asynchronously so ingestion is not coupled to downstream latency.
• Persist durable order state and support transactional updates.
• Store credentials and other sensitive configuration outside source code.
• Provide application logs, metrics, traces, and auditable administrative activity.
• Support repeatable infrastructure deployment from version-controlled IaC.
• Provide a documented rollback and dead-letter/replay approach.

Non-functional requirements

• Target 99.9% monthly availability for the public ingestion endpoint.
• Target p95 acknowledgement latency below 500 ms under the expected baseline load.
• Provide encryption in transit and at rest.
• Scale horizontally for bursty traffic and isolate asynchronous work from ingestion.
• Apply least-privilege identities and private access to data services where practical.
• Retain operational and audit evidence for at least 90 days, subject to organizational policy.
• Ensure deployments are reproducible, reviewable, and non-destructive by default.

Constraints

• The target platform is Google Cloud.
• Terraform is the infrastructure-as-code language.
• No resources may be provisioned during architecture validation.
• Product selection is explicitly deferred until this requirements section is approved.
• The first release is a reference implementation, not a completed compliance certification.
• Region, budget, traffic volume, data residency, and regulatory classification are not yet supplied.

Assumptions

• Orders are JSON and contain an immutable order identifier.
• A single primary region is acceptable for the initial release.
• The service can tolerate eventual consistency for asynchronous fulfillment.
• A managed relational database is appropriate for transactional order state.
• CI has permission to run Terraform formatting, initialization without a backend, validation, and an optional credentialed plan.
• Application container images are published by a separate build pipeline.

Open questions

• What are peak requests per second, payload size, and daily order volume?
• Which identity provider and client authentication protocol are required?
• What RTO/RPO and disaster-recovery region are required?
• What data residency, PCI, GDPR, or other controls apply?
• Should the database be regional or cross-region, and what is the retention/deletion policy?
• Which downstream systems consume orders, and what delivery semantics do they require?
• What is the approved Google Cloud project, region, DNS zone, and naming convention?
• What are the maximum monthly budget and alerting escalation targets?

Product selection deferred during this step: true.