🛠 Docker Commands and Best Practices

🚀 Docker Commands and Best Practices#

📜 Essential Docker Commands#

1. Managing Containers#

• Run Containers:

  • docker run <image> - Run a container from an image.
  • docker run -d <image> - Run a container in detached mode.
  • docker run -p <host-port>:<container-port> <image> - Map ports to expose services.

• Inspect Containers:

  • docker ps - List running containers.
  • docker ps -a - List all containers (running and stopped).
  • docker inspect <container-id> - View detailed container information.
  • docker logs <container-id> - Fetch container logs.

• Manage Containers:

  • docker start <container-id> - Start a stopped container.
  • docker stop <container-id> - Stop a running container.
  • docker rm <container-id> - Remove a stopped container.
  • docker exec -it <container-id> <command> - Execute a command in a running container (e.g., bash or sh).

2. Building and Managing Images#

• Build Images:

  • docker build -t <image-name> . - Build an image from a Dockerfile.
  • docker build --no-cache -t <image-name> . - Build an image without using the cache.

• List and Remove Images:

  • docker images - List all images.
  • docker rmi <image-id> - Remove an image.

• Tagging and Pushing Images:

  • docker tag <image> <repository>:<tag> - Tag an image.
  • docker push <repository>:<tag> - Push an image to a registry.

3. Docker Networks#

• Create and Inspect Networks:

  • docker network create <network-name> - Create a custom network.
  • docker network ls - List available networks.
  • docker network inspect <network-name> - Display detailed network information.

• Connect Containers to Networks:

  • docker network connect <network-name> <container-id> - Connect a container to a network.
  • docker network disconnect <network-name> <container-id> - Disconnect a container from a network.

4. Troubleshooting and Cleanup#

• Debugging Containers:

  • docker logs <container-id> - View container logs.
  • docker exec -it <container-id> bash - Open a shell in a running container.
  • docker inspect <container-id> - Get container details.

• System Cleanup:

  • docker system prune - Remove unused data (stopped containers, networks, and dangling images).
  • docker volume prune - Remove unused volumes.
  • docker image prune - Remove dangling images.

• Health Check:

  • docker ps --filter "health=unhealthy" - List containers with failing health checks.

🧑‍💻 Best Practices for Docker#

1. Image Optimization#

• Minimize Image Size:

  • Use lightweight base images like alpine where possible.
  • Remove unnecessary files in the Dockerfile:

    RUN apt-get clean && rm -rf /var/lib/apt/lists/*

• Avoid Root User:

  • Run your application as a non-root user in the container:

    RUN addgroup -S appgroup && adduser -S appuser -G appgroup
    USER appuser

• Pin Dependencies:

  • Specify exact versions of dependencies to ensure consistent builds:

    RUN npm install express@4.17.1

2. Multi-Stage Builds#

• Reduce image size by separating build dependencies from runtime dependencies:

  # Stage 1: Build
  FROM node:18 AS builder
  WORKDIR /app
  COPY package.json package-lock.json ./
  RUN npm install
  COPY . .
  RUN npm run build
  
  # Stage 2: Runtime
  FROM node:18-alpine
  WORKDIR /app
  COPY --from=builder /app/dist ./dist
  RUN npm install --production
  CMD ["node", "dist/index.js"]