Docker Resource Management

Resource management ensures that containers do not use excessive resources.

CPU Management

# Limit CPU (1.5 cores)
docker run -d --cpus="1.5" myapp

# Set CPU shares (relative weight)
docker run -d --cpu-shares=512 myapp

# Pin to specific CPUs
docker run -d --cpuset-cpus="0,1" myapp

Memory Management

# Limit memory (512 MB)
docker run -d --memory="512m" myapp

# Limit memory + swap
docker run -d --memory="512m" --memory-swap="1g" myapp

# Memory reservation
docker run -d --memory-reservation="256m" myapp

Use Case: Application Resources

version: '3.8'

services:
  api:
    build: ./backend
    deploy:
      resources:
        limits:
          cpus: '1.0'
          memory: 512M
        reservations:
          cpus: '0.5'
          memory: 256M

  database:
    image: postgres:15
    deploy:
      resources:
        limits:
          cpus: '2.0'
          memory: 2G
        reservations:
          cpus: '1.0'
          memory: 1G

  redis:
    image: redis:7-alpine
    deploy:
      resources:
        limits:
          cpus: '0.5'
          memory: 256M

Monitoring Resources

# Real-time stats
docker stats

# Stats for specific containers
docker stats api database redis

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

Everyday Use Case

Case: A container is using excessive CPU.

# View resource usage
docker stats

# Limit CPU
docker update --cpus="1.0" api

# Limit memory
docker update --memory="512m" api

OOM Killer

# Disable the OOM killer
docker run -d --oom-kill-disable --memory="512m" myapp

# Adjust the OOM score
docker run -d --oom-score-adj=-500 myapp

Best Practices

1. Set resource limits: For every container
2. Monitor usage: Use docker stats
3. Use healthchecks: For problem detection
4. Scale horizontally: Instead of vertical scaling

Conclusion

Resource management is important for system stability. Set limits for every container and monitor usage regularly.