Docker Operations

Quick reference for Docker container management and debugging.

When to Use This Skill

Use this skill when:

• Managing Docker containers
• Debugging container issues
• Checking container logs
• Cleaning up Docker resources
• Inspecting container state

Quick Status Commands

List Containers

# Running containers
docker ps

# All containers (including stopped)
docker ps -a

# With size info
docker ps -s

# Custom format
docker ps --format "table {{.Names}}\t{{.Status}}\t{{.Ports}}"

Container Logs

# View logs
docker logs <container>

# Follow logs (live)
docker logs -f <container>

# Last N lines
docker logs --tail 100 <container>

# With timestamps
docker logs -t <container>

# Since time
docker logs --since 1h <container>

Resource Usage

# Live stats for all containers
docker stats

# One-time stats (no stream)
docker stats --no-stream

# Specific container
docker stats <container>

Container Management

Start/Stop/Restart

# Start stopped container
docker start <container>

# Stop running container
docker stop <container>

# Restart container
docker restart <container>

# Kill (force stop)
docker kill <container>

Execute Commands

# Run command in container
docker exec <container> <command>

# Interactive shell
docker exec -it <container> /bin/sh
docker exec -it <container> /bin/bash

# As root
docker exec -u root -it <container> /bin/sh

Inspect Container

# Full inspect output
docker inspect <container>

# Get specific field
docker inspect -f '{{.State.Status}}' <container>
docker inspect -f '{{.NetworkSettings.IPAddress}}' <container>
docker inspect -f '{{json .Config.Env}}' <container>

Image Management

List Images

# All images
docker images

# With digests
docker images --digests

# Dangling images only
docker images -f "dangling=true"

Pull/Push

# Pull image
docker pull <image>:<tag>

# Push image
docker push <image>:<tag>

Cleanup Commands

Safe Cleanup

# Remove stopped containers
docker container prune -f

# Remove unused images
docker image prune -f

# Remove unused volumes
docker volume prune -f

# Remove unused networks
docker network prune -f

# Full system cleanup (safe - only unused)
docker system prune -f

Check Disk Usage

# Docker disk usage summary
docker system df

# Detailed breakdown
docker system df -v

Debugging

Container Not Starting

# Check container state
docker inspect -f '{{.State.Status}}' <container>
docker inspect -f '{{.State.Error}}' <container>

# Check logs
docker logs <container>

# Check events
docker events --since 1h --filter container=<container>

Network Issues

# List networks
docker network ls

# Inspect network
docker network inspect <network>

# Check container network
docker inspect -f '{{json .NetworkSettings.Networks}}' <container>

# Test connectivity from container
docker exec <container> ping -c 3 <host>
docker exec <container> curl -v <url>

Resource Issues

# Check container resource limits
docker inspect -f '{{.HostConfig.Memory}}' <container>
docker inspect -f '{{.HostConfig.CpuShares}}' <container>

# Live resource usage
docker stats <container> --no-stream

Common Patterns

Run One-Off Command

# Run and remove after
docker run --rm <image> <command>

# Example: check version
docker run --rm alpine cat /etc/alpine-release

Copy Files

# Copy from container to host
docker cp <container>:/path/to/file ./local/path

# Copy from host to container
docker cp ./local/file <container>:/path/in/container

View Container Processes

# Processes in container
docker top <container>

Quick Troubleshooting

Related Skills

• k8s-debug: For Kubernetes container debugging
• log-analysis: For log pattern analysis