9.1.2.2 Compose Local Caches

Compose local caches are caching services — typically Redis or Memcached — defined within a Compose file, providing a developer with a consistent local caching layer for development and testing without needing to install and manage that caching software directly on their machine.

Defining a Local Cache Service

A cache service definition is typically minimal, since most caching software requires little configuration to run for local development purposes.

services:
  cache:
    image: redis:7
    ports:
      - "6379:6379"

Why Caches Typically Don't Need a Volume for Local Development

Unlike a database, a local development cache's content is often perfectly fine to lose between restarts, since cached data is by nature derived and regenerable — many local cache setups intentionally omit a volume, relying on the cache simply repopulating itself as the application runs.

services:
  cache:
    image: redis:7

Without an explicit volume, this cache's data exists only in its container's writable layer (or, depending on configuration, only in memory), which is generally an acceptable trade-off for local development use.

Connecting an Application to the Local Cache

An application configured to use this cache references it by the Compose service name, exactly as it would reference any other Compose-defined service.

services:
  api:
    environment:
      - CACHE_URL=redis://cache:6379
  cache:
    image: redis:7

Resetting the Cache to a Clean State

Restarting the cache service provides an effectively clean cache state, useful when testing behavior that depends on cache content being absent.

docker compose restart cache

Why Compose Local Caches Matter

Defining a local caching service through Compose provides the same convenience and consistency benefits as a local database — a reliable, easily managed dependency available to every developer on a team without requiring direct installation, configured identically across everyone's development environment.