Docker Compose Redis Healthcheck - Guarantee Startup Order

Problem

depends_on alone only guarantees the Redis container has “started”, not that it’s “ready”. If the app connects while Redis is still initializing, you get Connection refused errors.

Solution

services:
  app:
    build: .
    depends_on:
      redis:
        condition: service_healthy  # start only when healthy
    environment:
      - REDIS_URL=redis://redis:6379

  redis:
    image: redis/redis-stack:latest
    environment:
      - REDIS_ARGS=--maxmemory 512mb --maxmemory-policy allkeys-lru
    healthcheck:
      test: ["CMD", "redis-cli", "ping"]
      interval: 10s
      timeout: 5s
      retries: 5
      start_period: 30s
    volumes:
      - redis-data:/data
    deploy:
      resources:
        limits:
          memory: 768M

volumes:
  redis-data:

Key Points

• redis-cli ping returning PONG signals healthy status. start_period: 30s gives Redis 30 seconds to initialize without being marked unhealthy.
• --maxmemory-policy allkeys-lru auto-evicts the oldest keys when memory is full. The safest default for cache use cases.
• deploy.resources.limits.memory prevents Redis from consuming all host memory. Set container-level limits independently of Redis’s maxmemory.