Monthly Review — Month 5: gRPC, Architecture & Microservices¶

Journal index · Roadmap › this month · Release notes

🎬 Headline¶

I can design, build, test, document, and release a real gRPC + Redis-queue microservice — hexagonally layered, resilient (retries/backoff/jitter/DLQ), observable (metrics), and operable (health, reflection, graceful shutdown).

🛠️ Skills Acquired¶

Skill	Confidence (1-5)	Evidence (link)
Protobuf/gRPC wire & error model	4	examples/month-05/protowire, statuscodes
Interceptors, TLS, REST transcoding	4	interceptors, tls, transcoding
gRPC service skeleton + graceful lifecycle	3	Day 134
Hexagonal architecture / ports & adapters	4	hexagonal, manualdi
Redis-backed queue + worker pool	3	jobqueue, workerpool
Resilience: backoff, jitter, DLQ, idempotency	4	retry, exercises/.../deadletter
Race-clean tests + Prometheus-style metrics	3	metrics, exercises/.../metrics
Docs & ADRs	4	Day 139

📦 Projects Completed¶

Capstone: gRPC + Redis job-queue microservice — gRPC API → hexagonal core → Redis queue → resilient workers → metrics → docs/ADRs. Key learning: a service is a domain core wrapped in adapters wrapped in middleware; resilience and observability are first-class, not afterthoughts.

💡 Lessons Learned¶

Dependencies point inward: the core owns its ports; adapters conform and translate infra errors to domain errors.
GracefulStop over Stop; drive shutdown from signal.NotifyContext.
Redis lists are queues; BRPOPLPUSH buys at-least-once delivery, which forces idempotent handlers.
Only the producer closes a channel, once; buffered capacity is backpressure.
Retry only transient errors, with overflow-safe backoff + full jitter, under a budget; dead-letter the rest with a %w-wrapped cause.
Sort label keys, avoid unbounded label cardinality, and run concurrency tests under -race.
ADRs freeze the why so settled design debates stay settled.

📉 Areas for Improvement¶

Streaming RPCs (interceptors + tests) — still the thinnest spot from Week 2.
Operational depth: reclaiming stuck jobs, picking budgets/caps from SLOs, DLQ re-drive tooling.
Metrics interceptor and histograms with sensible custom buckets.

🔁 Concepts to Keep Reviewing (carry into spaced repetition)¶

Interceptor chain order (first = outermost) and TLS trust model (CA/SAN/validity).
Channel axioms: closed-channel receive, who-closes, nil-channel blocking.
errors.Is/As vs string matching; %w wrapping.
At-least-once ⇒ idempotency; backoff + full jitter; DLQ.

🧑‍💼 Interview Readiness¶

Area	Ready?	Notes
Language fundamentals	✅	Solid since Months 1–2; reinforced via interface design this month.
Concurrency	✅	Worker pool, channel ownership, `-race`, context cancellation.
Web/DB	✅	M4 REST/DB + this month's gRPC/transcoding/Redis.
Architecture & systems design	🟧	Can explain hexagonal, queue-based decoupling, retries/DLQ/idempotency; want more on scaling/streaming.
Observability	🟧	Metrics fundamentals (RED) in hand; tracing/logging depth comes in Month 6.

🎒 Portfolio Updates¶

Updated capstone README (quickstart, grpcurl example, architecture sketch)
New résumé bullet: "Built a hexagonally-layered gRPC microservice with a Redis-backed job queue, resilient retries/dead-letter, and Prometheus-style metrics in Go."
Pinned/featured: the Month 5 capstone repo path
Tagged release v0.5.0 + wrote release notes
Authored ADRs (hexagonal layering, Redis broker, at-least-once + idempotency)

📊 Metrics¶

Total hours	Days completed	Exercises	Projects	Books/articles	Avg confidence
42	28/28	9	1	12	3.6/5

⏭️ Next Month Preview¶

Month 6 — Production, Observability & Capstone: structured logging, metrics in depth, distributed tracing across the queue boundary, containerization/deployment, load testing, and the final capstone polish toward v0.6.0.

Suggested commit: docs(journal): month 5 review then git tag -a v0.5.0 -m "Month 5 complete"