# 5. Production checklist: which one, for what

[Previous: 04-concurrency-limit.md](04-concurrency-limit.md) | [README](../README.md)

A decision list, built from what chapters 1-4 actually demonstrated rather than from either
library's marketing:

- **Need a circuit breaker (state that remembers a dependency is down across calls)?**
  Resilience4j. Nothing in Spring Framework 7 core does this — verified by grepping
  `spring-context-7.0.9.jar` for `circuitbreaker` (zero matches). See [chapter 1](01-two-resilience-stacks.md).
- **Need declarative retry with backoff, and don't already depend on Resilience4j?**
  `@Retryable` from core is genuinely enough — one annotation, no extra dependency, verified
  attribute set in [chapter 1](01-two-resilience-stacks.md). Remember it has no fallback and no
  memory between calls ([chapter 3](03-spring-retryable.md)).
- **Need a rate limiter (calls per second, not concurrent calls)?** Resilience4j. There is no
  rate limiter in Framework 7 core at all.
- **Need to cap concurrency, and unlimited blocking for the overflow is acceptable?**
  `@ConcurrencyLimit(policy = BLOCK)` — one annotation.
- **Need to cap concurrency with a bounded wait before giving up?** Resilience4j's Bulkhead
  with `maxWaitDuration` — `@ConcurrencyLimit` has no equivalent ([chapter 4](04-concurrency-limit.md)).
- **Need Actuator health/metrics integration, a dashboard, Micrometer gauges per instance?**
  Resilience4j — `management.health.circuitbreakers.enabled=true` and the
  `resilience4j_circuitbreaker_*` Micrometer series have no equivalent for the core annotations.
- **Migrating off Resilience4j specifically to cut a dependency?** You can drop it only for the
  retry and simple-throttle cases above. Circuit breaking and rate limiting are not replaced;
  they're just gone if you remove the dependency.

## Gotchas that apply to both, not just one

- `@EnableResilientMethods` is not auto-configured by Boot 4.1 — add it yourself ([chapter 1](01-two-resilience-stacks.md)).
- `spring-boot-starter-aop` does not exist on Boot 4 — use `spring-aop` directly, and add
  `aspectjweaver` explicitly if you're using Resilience4j's `@Aspect`-based integration, or
  the annotations will silently do nothing ([chapter 1](01-two-resilience-stacks.md)).
- Self-invocation bypasses both, silently, the same way it always has for `@Transactional` and
  `@Async` ([chapter 3](03-spring-retryable.md)).

## Before shipping this repo's app

Nothing here needs removing before production — there's no diagnostic endpoint exposing
internals, just the standard Actuator `health`/`metrics`/`circuitbreakers` set, which is meant
to be exposed (behind auth) in production anyway.