Deployment Automation

Deployment Automation

Manage Docker Compose deployments, container lifecycle, image updates, and rollbacks.

Quick Start

Deploy a Compose Stack

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# Start services
docker compose up -d

# Start with rebuild
docker compose up -d --build

# Check status
docker compose ps

Update a Running Service

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# Pull latest images
docker compose pull

# Recreate with new images
docker compose up -d --remove-orphans

# Verify health
docker compose ps
docker compose logs --tail=20 <service>

Docker Compose Management

Lifecycle Commands

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# Start all services
docker compose up -d

# Stop all services (preserves volumes)
docker compose down

# Stop and remove volumes (DESTRUCTIVE)
docker compose down -v

# Restart a specific service
docker compose restart <service>

# Scale a service
docker compose up -d --scale <service>=3

# View logs
docker compose logs -f <service>
docker compose logs --tail=50 <service>

Stack Health Check

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# List all containers with status
docker compose ps --format "table {{.Name}}\t{{.Status}}\t{{.Ports}}"

# Check resource usage
docker stats --no-stream --format "table {{.Name}}\t{{.CPUPerc}}\t{{.MemUsage}}"

# Inspect a specific container
docker inspect <container> | jq '.[0].State'

Image Update Workflow

Safe update process with rollback path:

Step 1: Pre-Update Checks

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# Record current state
docker compose ps > /tmp/pre-update-state.txt
docker compose config --images > /tmp/current-images.txt

# Check current image digests
docker compose images --format "table {{.Repository}}\t{{.Tag}}\t{{.ID}}"

Step 2: Pull New Images

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# Pull latest images
docker compose pull

# Compare image IDs (see if anything changed)
docker compose images --format "table {{.Repository}}\t{{.Tag}}\t{{.ID}}"

Step 3: Deploy Update

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# Recreate containers with new images
docker compose up -d --remove-orphans

# Wait for services to stabilize
sleep 10

# Verify all containers are healthy
docker compose ps

Step 4: Post-Update Verification

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# Check for restart loops
docker compose ps --format "{{.Name}}: {{.Status}}" | grep -i "restarting"

# Check logs for errors
docker compose logs --since 2m --tail=50 2>&1 | grep -iE "error|fatal|panic"

# Test service endpoints
curl -s -o /dev/null -w "%{http_code}" http://localhost:<port>/health

Step 5: Rollback (If Needed)

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# Rollback to previous image
docker compose down
# Edit compose file or use specific image tags
docker compose up -d

# Or if you tagged the previous image:
docker tag <service>:previous <service>:latest
docker compose up -d

Health Check Patterns

In Compose Files

Always include health checks in new deployments:

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services:
  myservice:
    image: myimage:latest
    healthcheck:
      test: ["CMD", "curl", "-f", "http://localhost:8080/health"]
      interval: 30s
      timeout: 10s
      retries: 3
      start_period: 40s
    restart: unless-stopped

Common Health Check Types

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# HTTP endpoint
healthcheck:
  test: ["CMD", "curl", "-f", "http://localhost:8080/health"]

# TCP port
healthcheck:
  test: ["CMD", "nc", "-z", "localhost", "5432"]

# Command execution
healthcheck:
  test: ["CMD", "pg_isready", "-U", "postgres"]

# Shell command
healthcheck:
  test: ["CMD-SHELL", "wget -q --spider http://localhost:80 || exit 1"]

Monitor Health Status

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# Check health status of all containers
docker ps --format "table {{.Names}}\t{{.Status}}"

# Inspect health details
docker inspect --format='{{json .State.Health}}' <container> | jq '.'

# Watch for unhealthy containers
docker ps --filter "health=unhealthy"

Container Cleanup

Regular Maintenance

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# Remove stopped containers
docker container prune -f

# Remove unused images
docker image prune -f

# Remove unused images (including tagged)
docker image prune -a -f

# Remove unused volumes (CAREFUL — data loss)
docker volume prune -f

# Remove unused networks
docker network prune -f

# Full cleanup (containers, images, networks — NOT volumes)
docker system prune -f

# Full cleanup INCLUDING volumes (DESTRUCTIVE)
docker system prune -a --volumes -f

Disk Usage

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# Docker disk usage summary
docker system df

# Detailed breakdown
docker system df -v

Compose File Best Practices

Template for New Services

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version: "3.8"

services:
  servicename:
    image: image:tag          # Pin to specific tag, not :latest for production
    container_name: servicename
    restart: unless-stopped
    healthcheck:
      test: ["CMD", "curl", "-f", "http://localhost:8080/health"]
      interval: 30s
      timeout: 10s
      retries: 3
      start_period: 40s
    environment:
      - TZ=Etc/UTC
    volumes:
      - servicename_data:/data
    ports:
      - "8080:8080"
    networks:
      - default
    logging:
      driver: json-file
      options:
        max-size: "10m"
        max-file: "3"

volumes:
  servicename_data:

networks:
  default:

Key Principles

1. Pin image tags — Use image:1.2.3 not image:latest for production
2. Always health check — Every service should have a health check
3. Always restart policy — unless-stopped or always
4. Log rotation — Set max-size and max-file to prevent disk fill
5. Named volumes — Use named volumes, not bind mounts, for data persistence
6. Timezone — Set TZ=Etc/UTC for consistent logs
7. Resource limits — Set memory/CPU limits for critical services

Resource Limits

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services:
  myservice:
    deploy:
      resources:
        limits:
          memory: 512M
          cpus: "0.5"
        reservations:
          memory: 256M
          cpus: "0.25"

Rollback Strategies

Strategy 1: Image Tag Pinning

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# Before update: note current tag
docker compose images

# Update compose file to new tag
# If it fails: revert compose file to old tag
docker compose up -d

Strategy 2: Docker Image Tagging

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# Tag current image before updating
docker tag myimage:latest myimage:rollback
docker compose pull
docker compose up -d

# If it fails:
docker tag myimage:rollback myimage:latest
docker compose up -d

Strategy 3: Compose File Versioning

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# Keep previous compose file
cp docker-compose.yml docker-compose.yml.bak

# Deploy new version
docker compose up -d

# If it fails:
cp docker-compose.yml.bak docker-compose.yml
docker compose up -d

Troubleshooting

Container Won't Start

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# Check logs
docker compose logs <service>

# Check if port is already in use
ss -tlnp | grep <port>

# Check if image exists
docker images | grep <image>

# Try running interactively
docker compose run --rm <service> sh

Container Keeps Restarting

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# Check restart count
docker inspect <container> --format='{{.RestartCount}}'

# Check exit code
docker inspect <container> --format='{{.State.ExitCode}}'

# Check OOM kill
docker inspect <container> --format='{{.State.OOMKilled}}'

# View last logs before crash
docker logs --tail=50 <container>

Out of Disk Space

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# Check Docker disk usage
docker system df

# Identify large images
docker images --format "{{.Repository}}:{{.Tag}} {{.Size}}" | sort -k2 -h

# Clean up
docker system prune -f
docker image prune -a -f

Kai skill — Docker deployment and lifecycle management