ADR-0003: PSR-6 Cache and PSR-3 Logger — Standards-Based Injection

Status

Accepted

Context

The Contentful PHP CDA SDK supports optional caching (PSR-6 CacheItemPoolInterface) and logging (PSR-3 LoggerInterface). The bundle must allow Symfony applications to wire their existing cache and logging infrastructure into the SDK clients without prescribing specific implementations.

Options considered:

1. Hard-code Symfony cache/logger — tightest coupling, least flexible
2. Accept service IDs as config strings — flexible, but string-typed, error-prone
3. Accept PSR interface service IDs with a default to Symfony's autowired instances — idiomatic Symfony: leverage the container's PSR interface aliases

Decision

Configuration accepts service IDs (strings) for options.logger and options.cache.pool. At compile time, ContentfulExtension::configureDeliveryOptions() converts these strings to Reference objects pointing to the specified services. The defaults are Psr\Log\LoggerInterface and Psr\Cache\CacheItemPoolInterface — the standard container aliases that Symfony's MonologBundle and CacheBundle register automatically.

This means:

• Zero config needed for cache/logger in most apps (Symfony auto-wires them)
• Custom implementations are supported by specifying a different service ID
• No Symfony-specific types leak into the CDA SDK

Consequences

• Applications must have a PSR-6 cache pool registered under Psr\Cache\CacheItemPoolInterface to use the default; if absent and cache is configured, container compilation fails with a missing service error
• The psr/log requirement was added in bundle 7.1.0 (previously implicit via contentful/contentful) to make the dependency explicit and allow psr/log v2/v3
• Swapping implementations (e.g., Redis vs APCu cache pool) requires only a config change, not code changes