Cheat SheetsDockerProduction

Production — Cheat Sheet

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Cheat Sheet · AiCanCode.org
Production
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Production Patterns — Health Checks, Restart Policies & Logging

Running containers in production requires health checks, restart policies, log management, and resource limits to ensure reliability, observability, and efficient resource use.

  • ✓HEALTHCHECK defines how Docker probes application health (not just process alive).
  • ✓Unhealthy containers are automatically restarted based on the restart policy.
  • ✓Handle SIGTERM in your application for graceful shutdown — drain in-flight requests before exiting.
  • ✓Default json-file log driver loses logs when a container is removed — use centralised logging in production.
  • ✓Set max-size and max-file on the json-file driver to prevent disk exhaustion.
  • ✓The start-period in HEALTHCHECK prevents premature unhealthy marking during slow startup (e.g., JVM warmup).
Dockerfile + Compose — health checks
# Dockerfile HEALTHCHECK

HEALTHCHECK --interval=30s \     # check every 30s

            --timeout=5s \       # mark unhealthy if check takes >5s

            --start-period=10s \ # grace period after container starts

            --retries=3 \        # 3 consecutive failures = unhealthy

  CMD curl -f http://localhost:8000/health || exit 1



# Or use wget (smaller than curl in Alpine)

HEALTHCHECK CMD wget -qO- http://localhost:8000/health || exit 1



# Check health status

docker ps

# STATUS

# Up 5 minutes (healthy)

# Up 2 minutes (unhealthy)

# Up 10 seconds (starting)   ← during start-period



# Inspect health history

docker inspect --format='{{json .State.Health}}' my-container | jq



# In docker-compose.yml (inline healthcheck):

services:

  api:

    image: my-api

    healthcheck:

      test: ["CMD", "curl", "-f", "http://localhost:8000/health"]

      interval: 30s

      timeout: 10s

      retries: 3

      start_period: 40s
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