8 snippets

Docker

Practical Docker commands for container lifecycle management, image building, log inspection, resource cleanup, and networking.

Using Docker Compose?Most commands here use the Docker CLI. For Compose workflows, prefix with docker compose (e.g., docker compose up -d).

Container Quick Reference

Most-used Docker container commands for listing, starting, stopping, and removing containers.

bash

# List running containers
docker ps

# List all containers (including stopped)
docker ps -a

# Stop a running container
docker stop <container_id_or_name>

# Remove a stopped container
docker rm <container_id_or_name>

# Force remove a running container
docker rm -f <container_id_or_name>

Build & Tag an Image

Build a Docker image from a Dockerfile in the current directory and tag it with a name and version. Use '.' to build from current directory.

bash

# Build with tag
docker build -t myapp:1.0.0 .

# Build with build args
docker build \
  --build-arg NODE_ENV=production \
  --build-arg APP_PORT=3000 \
  -t myapp:latest .

# List local images
docker images

Run Container with Options

Start a container with common options: detached mode, port mapping, environment variables, and automatic restart policy.

bash

docker run -d \
  --name myapp \
  --restart unless-stopped \
  -p 3000:3000 \
  -e NODE_ENV=production \
  -e DATABASE_URL=postgres://user:pass@db:5432/mydb \
  -v /host/data:/app/data \
  myapp:latest

Container Logs

View and follow container logs. Use --since to limit to recent logs, and --tail to cap output. Useful for debugging production issues.

bash

# Follow live logs
docker logs -f myapp

# Last 100 lines
docker logs --tail 100 myapp

# Logs from last 1 hour
docker logs --since 1h myapp

# Logs between timestamps
docker logs --since "2025-01-01T10:00:00" --until "2025-01-01T11:00:00" myapp

Execute Command Inside Container

Open an interactive shell inside a running container. Use sh if bash is not available (Alpine-based images).

bash

# Open bash shell
docker exec -it myapp bash

# Open sh (for Alpine/minimal images)
docker exec -it myapp sh

# Run a single command
docker exec myapp cat /etc/os-release

# Run as root (useful for debugging)
docker exec -it -u root myapp bash

System Cleanup

Free up disk space by removing stopped containers, dangling images, unused networks, and build cache. Use with caution in production.

bash

# Remove all stopped containers
docker container prune -f

# Remove dangling images (untagged)
docker image prune -f

# Remove all unused images (not just dangling)
docker image prune -a -f

# Nuclear option: remove everything unused
docker system prune -a --volumes -f

# Check disk usage first
docker system df

Network & Volume Management

Manage Docker networks and volumes. Useful when containers need to communicate or share persistent data.

bash

# List networks
docker network ls

# Create a custom bridge network
docker network create mynetwork

# Inspect container's network settings
docker inspect --format='{{json .NetworkSettings}}' myapp | jq

# List volumes
docker volume ls

# Remove unused volumes
docker volume prune -f

# Inspect a volume mount path
docker volume inspect myvolume

Container Resource Usage

Monitor real-time CPU, memory, network, and block I/O usage for running containers. Useful for performance debugging.

bash

# Live stats for all containers
docker stats

# Stats for a specific container (no-stream = snapshot)
docker stats --no-stream myapp

# Inspect container config (ports, env, mounts, etc.)
docker inspect myapp

# Check container exit code and reason
docker inspect myapp --format='{{.State.ExitCode}} {{.State.Error}}'