/spring-boot-cache

name: spring-boot-cache
description: "Provides patterns for implementing Spring Boot caching: configures Redis/Caffeine/EhCache providers with TTL and eviction policies, applies @Cacheable/@CacheEvict/@CachePut annotations, validates cache hit/miss behavior, and exposes metrics via Actuator. Use when adding caching to Spring Boot services, configuring cache expiration, evicting stale data, or diagnosing cache misses."
allowed-tools: Read, Write, Bash

Spring Boot Cache Abstraction

Overview

6-step workflow for enabling cache abstraction, configuring providers (Caffeine, Redis, Ehcache), annotating service methods, and validating behavior in Spring Boot 3.5+ applications. Apply `@Cacheable` for reads, `@CachePut` for writes, `@CacheEvict` for deletions. Configure TTL/eviction policies and expose metrics via Actuator.

When to Use

• Add `@Cacheable`, `@CachePut`, or `@CacheEvict` to service methods.
• Configure Caffeine, Redis, or Ehcache with TTL and capacity policies.
• Implement eviction strategies for stale data.
• Diagnose cache misses or invalidation issues.
• Expose hit/miss metrics via Actuator or Micrometer.

Instructions

1. **Add dependencies** — `spring-boot-starter-cache` plus a provider:

• Caffeine: `caffeine` starter
• Redis: `spring-boot-starter-data-redis`
• Ehcache: `ehcache` starter

2. **Enable caching** — annotate a `@Configuration` class with `@EnableCaching` and define a `CacheManager` bean.

3. **Annotate methods** — `@Cacheable` for reads, `@CachePut` for writes, `@CacheEvict` for deletions.

4. **Configure TTL/eviction** — set `spring.cache.caffeine.spec`, `spring.cache.redis.time-to-live`, or `spring.cache.ehcache.config`.

5. **Shape keys** — use SpEL in `key` attributes; guard with `condition`/`unless` for selective caching.

6. **Validate setup** — run integration test to confirm cache hit on second call; check `GET /actuator/caches` to verify cache manager registration; query `GET /actuator/metrics/cache.gets` for hit/miss ratios.

Examples

Example 1: Basic `@Cacheable` Usage

@Service
@CacheConfig(cacheNames = "users")
class UserService {

    @Cacheable(key = "#id", unless = "#result == null")
    User findUser(Long id) { ... }
}

First call → cache miss, repository invoked
Second call → cache hit, repository skipped

Example 2: Conditional Caching with SpEL

@Cacheable(value = "products", key = "#id", condition = "#price > 100")
public Product getProduct(Long id, BigDecimal price) { ... }

// Only expensive products are cached

Example 3: Cache Eviction

@CacheEvict(value = "users", key = "#id")
public void deleteUser(Long id) { ... }

For progressive scenarios (basic product cache, multilevel eviction, Redis integration), load [`references/cache-examples.md`](references/cache-examples.md).

Advanced Options

• Use JCache annotations (`@CacheResult`, `@CacheRemove`) for providers favoring

JSR-107 interoperability; avoid mixing with Spring annotations on the same method.

• Cache reactive return types (`Mono`, `Flux`) or `CompletableFuture` values.
• Apply HTTP `CacheControl` headers when exposing cached responses via REST.
• Schedule periodic eviction with `@Scheduled` for time-bound caches.
• Create a `CacheManagementService` for programmatic `cacheManager.getCache(name)`.

Troubleshooting

If cache misses persist after adding `@Cacheable`:

1. Verify `@EnableCaching` is present on a `@Configuration` class. 2. Confirm the method is public and called from outside the class (Spring uses proxies; self-invocation bypasses the cache). 3. Validate SpEL key expressions resolve correctly. 4. Confirm the cache manager bean is registered as `cacheManager` or explicitly referenced via `cacheManager = "myCacheManager"`.

References

• [`references/spring-framework-cache-docs.md`](references/spring-framework-cache-docs.md):

curated excerpts from Spring Framework Reference Guide.

• [`references/spring-cache-doc-snippet.md`](references/spring-cache-doc-snippet.md):

narrative overview from Spring documentation.

• [`references/cache-core-reference.md`](references/cache-core-reference.md):

annotation parameters, dependency matrices, property catalogs.

• [`references/cache-examples.md`](references/cache-examples.md):

end-to-end examples with tests.

Best Practices

• Prefer constructor injection and immutable DTOs for cache entries.
• Separate cache names per aggregate (`users`, `orders`) to simplify eviction.
• Log cache hits/misses only at debug; push metrics via Micrometer.
• Tune TTLs based on data staleness tolerance; document rationale in code.
• Guard caches storing PII or credentials with encryption or avoid caching.
• Align cache eviction with transactional boundaries to prevent dirty reads.

Constraints and Warnings

• Avoid caching mutable entities that depend on open persistence contexts.
• Do not mix Spring cache annotations with JCache annotations on the same method.
• Validate serialization compatibility when caching across service instances.
• Monitor memory footprint to prevent OOM with in-memory stores.
• Caffeine + Redis multi-level caches require publish/subscribe invalidation channels.

Related Skills

• [`../spring-boot-rest-api-standards`](../spring-boot-rest-api-standards/SKILL.md)
• [`../spring-boot-test-patterns`](../spring-boot-test-patterns/SKILL.md)
• [`../unit-test-caching`](../unit-test-caching/SKILL.md)