Essential Docker Commands and Techniques for Developers

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Introduction

Welcome to the 👋

Whether you're a novice exploring the world of or a seasoned pro seeking a quick reference, you're in the right place. This comprehensive guide is designed to address both beginners and experienced users, offering a thorough exploration of essential Docker commands and concepts.

Explore creating and managing Docker images, understand , and master Dockerfile syntax, dive into complexities, and learn the latest features like with clear explanations, step-by-step guidance, and practical illustrative examples.

With all the necessary commands and concepts, this guide will help you get started with Docker real quickly. Go ahead and give it a read!

Happy Dockering!

Docker Image

1. Build an image from a Dockerfile:

docker build -t myapp .

2. List all local images:

docker image ls

3. Pull an image from Docker Hub:

docker pull nginx:latest

4. Remove a local image:

docker rmi myapp:latest

or

docker rm fd484f19954f

5. Tag an image:

docker tag myapp:latest myapp:v1

6. Push an image to Docker Hub:

docker push myapp:v1

7. Inspect details of an image:

docker image inspect myapp:v1

8. Save an image to a tar archive:

docker save -o myapp.tar myapp:v1

9. Load an image from a tar archive:

docker load -i myapp.tar

10. Prune unused images:

docker image prune

Docker Container

1. Run a container from an image:

docker run myapp

2. Run a named container from an image:

docker run --name my_container myapp:v1

3. List all running containers:

docker ps

4. List all containers (including stopped ones):

docker ps -a

5. Stop a running container:

docker stop my_container

6. Start a stopped container:

docker start my_container

7. Run container in interactive mode:

docker run -it my_container

8. Run container in interactive shell mode:

docker run -it my_container sh

9. Remove a stopped container:

docker rm my_container

10. Remove a running container (forcefully):

docker rm -f my_container

11. Inspect details of a container:

docker inspect my_container

12. View container logs:

docker logs my_container

13. Pause a running container:

docker pause my_container

14. Unpause a paused container:

docker unpause my_container

Docker Volumes and Network

Volumes:

1. Create a named volume:

docker volume create my_volume

2. List all volumes:

docker volume ls

3. Inspect details of a volume:

docker volume inspect my_volume

4. Remove a volume:

docker volume rm my_volume

5. Run a container with a volume (mount):

docker run --name my_container -v my_volume:/app/data myapp:v1

6. Copy files between a container and a volume:

docker cp data.txt my_container:/app/data

Network (Port Mapping):

1. Run a container with port mapping:

docker run --name my_container -p 8080:80 myapp

2. List all networks:

docker network ls

3. Inspect details of a network:

docker network inspect bridge

4. Create a user-defined bridge network:

docker network create my_network

5. Connect a container to a network:

docker network connect my_network my_container

6. Disconnect a container from a network:

docker network disconnect my_network my_container

Docker Compose

1. Create and start containers defined in a docker-compose.yml file:

docker compose up

This command reads the file and starts the defined services in the background.

2. Stop and remove containers defined in a docker-compose.yml file:

docker compose down

This command stops & removes the containers, networks, and volumes defined in the file.

3. Build or rebuild services:

docker compose build

This command builds or rebuilds the Docker images for the services defined in the file.

4. List containers for a specific Docker Compose project:

docker compose ps

This command lists the containers for the services defined in the file.

5. View logs for services:

docker compose logs

This command shows the logs for all services defined in the file.

6. Scale services to a specific number of containers:

docker compose up -d --scale web=3

This command scales the specified service to the desired number of containers.

7. Run a one-time command in a service:

docker compose run web npm install

This command runs a one-time command in the specified service container.

8. List all volumes:

docker volume ls

Docker Compose creates volumes for services. This command helps you see them.

9. Pause a service:

docker volume pause service_name

This command pauses the specified service.

10. Unpause a service:

docker volume unpause service_name

This command unpauses the specified service.

11. View details of a service:

docker compose ps service_name

This command provides detailed information about a specific service.

Latest Docker

1. Initialize Docker inside an application:

docker init

This command initializes Docker inside the application directory, setting up the necessary configuration files.

2. Watch the service/container of an application:

docker compose watch

It watches the build context for the service and rebuilds/refreshes containers when files are updated.

Dockerfile Reference

What is a Dockerfile?

A is a script that contains instructions for building a . It defines the , sets up , installs software, and configures the container for a specific application or service.

Docker Compose File Syntax

Version:

Specifies the of the Docker Compose file format.

version: '3.8'

Services:

Defines the /containers that make up the application.

services: 
   web: 
      image: nginx:latest

Networks:

Configures custom for the application.

networks:
  my_network:
    driver: bridge

Volumes:

Defines named that the services can use.

volumes:
  my_volume:

Environment:

Sets for a service.

environment:
  - NODE_ENV=production

Ports:

Maps host to container ports.

ports:
  - "8080:80"

Depends On:

Specifies between services, ensuring one service starts before another.

depends_on:
  - db

Build:

Configures the for a service.

build:
  context: .
  dockerfile: Dockerfile.dev

Volumes From:

Mounts from another service or container.

volumes_from:
  - service_name

Command:

Overrides the default specified in the Docker image.

command: ["npm", "start"]

Docker Compose File Example

Here's a simple Docker Compose file example for a web and database service:

version: '3.8'

// Define services for the MERN stack
services:

  // MongoDB service
  mongo:
    image: mongo:latest
    ports:
      - "27017:27017"
    volumes:
      - mongo_data:/data/db
    environment:
      MONGO_INITDB_ROOT_USERNAME: admin
      MONGO_INITDB_ROOT_PASSWORD: admin

  // Node.js (Express) API service
  api:
    build:
      // Specify the build context for the API service
      context: ./api
      // Specify the Dockerfile for building the API service
      dockerfile: Dockerfile
    ports:
      - "5000:5000"
    // Ensure the MongoDB service is running before starting the API
    depends_on:
      - mongo
    environment:
      MONGO_URI: mongodb://admin:admin@mongo:27017/mydatabase
    networks:
      - mern_network

  // React client service
  client:
    build:
      // Specify the build context for the client service
      context: ./client
      // Specify the Dockerfile for building the client service
      dockerfile: Dockerfile
    ports:
      - "3000:3000"
    // Ensure the API service is running before starting the client
    depends_on:
      - api
    networks:
      - mern_network

// Define named volumes for persistent data
volumes:
  mongo_data:

// Define a custom network for communication between services
networks:
  mern_network:

Congratulations! 🎉

You’ve successfully completed the guide to essential Docker commands and techniques! 🚢 You now have a solid foundation to:

• Manage containers effectively
• Streamline your development workflow
• Confidently deploy your applications

Remember, is a powerful tool that grows with you. The more you practice, the more proficient you’ll become. Dive into advanced features, experiment with real-world projects, and discover how Docker can transform your development process.

Explore Docker Compose, volumes, and networking to create even more efficient and scalable solutions.

Keep pushing boundaries, building amazing applications, and enjoying the journey!

Happy containerizing! 🚀