C4 — Container Diagram

The local and production shapes share the same service boundaries. Local Compose uses a compact grafana/otel-lgtm container for observability; production Helm keeps collector, metric, log, and trace backends independently deployable.

graph LR
  Client[Client apps and partners]
  Kong[Kong Gateway<br/>mTLS, rate-limit, correlation-id]
  Keycloak[Keycloak 26<br/>FAPI policies, PS256]
  Services[Finnest services<br/>Hono on Bun]
  Admin[Power Admin]
  CLI[Finnest CLI and TUI]
  Postgres[(PostgreSQL 18)]
  NATS[(NATS JetStream)]
  Redis[(Redis 8)]
  LGTM[Local grafana/otel-lgtm]
  Alloy[Production Alloy collector]

  Client --> Kong
  Kong --> Keycloak
  Kong --> Services
  Admin --> Services
  CLI --> Services
  Services --> Postgres
  Services --> NATS
  Services --> Redis
  Services --> LGTM
  Services --> Alloy

Container Responsibilities

• Kong owns public ingress concerns: mTLS, correlation IDs, CORS, and rate limiting.
• Keycloak owns OIDC/FAPI policy enforcement and signing keys.
• Finnest services own business APIs, repository access, domain validation, and emitted events.
• PostgreSQL owns durable business state, audit trails, migrations, and transactional outbox rows.
• NATS owns internal asynchronous delivery.
• Redis owns cache/rate-limit/shared ephemeral state.
• Observability receives OTLP traces, metrics, and logs with PII redaction already applied by services.