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🐳 Docker Commands: From Beginner to Advanced for DevOps Engineers

#docker #devops #cli #beginners

Introduction

Docker is a platform for developing, shipping, and running applications inside containers. It provides a lightweight, portable, and consistent environment for software development and deployment. This guide covers essential Docker commands from beginner to advanced levels, helping DevOps engineers effectively manage their containerized applications.

🎯 Key Concepts

Before diving into the commands, let's review some fundamental Docker concepts:

  • Image: A lightweight, standalone, and executable package that includes everything needed to run a piece of software.
  • Container: A runtime instance of a Docker image.
  • Dockerfile: A script containing a series of instructions on how to build a Docker image.
  • Docker Compose: A tool for defining and running multi-container Docker applications.

🏁 Beginner Commands

1. Installation

Check Docker Version 

docker --version
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Displays the installed version of Docker.

2. Docker Images

List Docker Images 

docker images
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Lists all Docker images on the local machine.

Pull Docker Image 

docker pull <image_name>
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Pulls a Docker image from a registry (e.g., Docker Hub).

Remove Docker Image 

docker rmi <image_name>
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Removes a Docker image from the local machine.

3. Docker Containers

List Running Containers 

docker ps
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Lists all running Docker containers.

List All Containers 

docker ps -a
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Lists all Docker containers, including stopped ones.

Run a Container 

docker run -d --name <container_name> <image_name>
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Runs a container from a Docker image in detached mode.

Stop a Container 

docker stop <container_name>
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Stops a running Docker container.

Start a Container 

docker start <container_name>
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Starts a stopped Docker container.

Remove a Container 

docker rm <container_name>
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Removes a Docker container.

View Container Logs 

docker logs <container_name>
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Displays the logs of a Docker container.

4. Docker Networks

List Docker Networks 

docker network ls
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Lists all Docker networks.

Create Docker Network 

docker network create <network_name>
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Creates a new Docker network.

Connect Container to Network 

docker network connect <network_name> <container_name>
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Connects a container to a Docker network.

Disconnect Container from Network 

docker network disconnect <network_name> <container_name>
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Disconnects a container from a Docker network.

🚀 Intermediate Commands

1. Docker Volumes

List Docker Volumes 

docker volume ls
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Lists all Docker volumes.

Create Docker Volume 

docker volume create <volume_name>
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Creates a new Docker volume.

Remove Docker Volume 

docker volume rm <volume_name>
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Removes a Docker volume.

Mount Volume to Container 

docker run -d --name <container_name> -v <volume_name>:/path/in/container <image_name>
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Mounts a Docker volume to a container.

2. Docker Compose

Install Docker Compose 

sudo curl -L "https://github.com/docker/compose/releases/download/<version>/docker-compose-$(uname -s)-$(uname -m)" -o /usr/local/bin/docker-compose
sudo chmod +x /usr/local/bin/docker-compose
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Installs Docker Compose.

Check Docker Compose Version 

docker-compose --version
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Displays the installed version of Docker Compose.

Docker Compose File Example 

version: '3'
services:
  web:
    image: nginx
    ports:
      - "80:80"
  db:
    image: mysql
    environment:
      MYSQL_ROOT_PASSWORD: example
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Defines a multi-container application using Docker Compose.

Run Docker Compose 

docker-compose up -d
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Runs the Docker Compose application in detached mode.

Stop Docker Compose 

docker-compose down
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Stops and removes the Docker Compose application.

3. Dockerfile

Dockerfile Example 

# Use an official Python runtime as a parent image
FROM python:3.8-slim

# Set the working directory in the container
WORKDIR /app

# Copy the current directory contents into the container at /app
COPY . /app

# Install any needed packages specified in requirements.txt
RUN pip install --no-cache-dir -r requirements.txt

# Make port 80 available to the world outside this container
EXPOSE 80

# Define environment variable
ENV NAME World

# Run app.py when the container launches
CMD ["python", "app.py"]
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Defines a Dockerfile for a Python application.

Build Docker Image 

docker build -t <image_name> .
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Builds a Docker image from a Dockerfile.

4. Docker Swarm

Initialize Docker Swarm 

docker swarm init
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Initializes a Docker Swarm.

List Swarm Nodes 

docker node ls
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Lists all nodes in the Docker Swarm.

Deploy Stack in Swarm 

docker stack deploy -c <compose-file> <stack_name>
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Deploys a stack in the Docker Swarm.

Remove Stack from Swarm 

docker stack rm <stack_name>
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Removes a stack from the Docker Swarm.

5. Docker Secrets

Create Docker Secret 

echo "my_secret_value" | docker secret create <secret_name> -
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Creates a new Docker secret.

List Docker Secrets 

docker secret ls
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Lists all Docker secrets.

Remove Docker Secret 

docker secret rm <secret_name>
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Removes a Docker secret.

🧠 Advanced Commands

1. Docker Inspect

Inspect Docker Container 

docker inspect <container_name>
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Displays detailed information about a Docker container.

Inspect Docker Image 

docker inspect <image_name>
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Displays detailed information about a Docker image.

2. Docker Stats

View Container Statistics 

docker stats <container_name>
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Displays real-time statistics for Docker containers.

3. Docker Events

View Docker Events 

docker events
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Displays real-time events from the Docker server.

4. Docker Export and Import

Export Container 

docker export <container_name> -o <file_name>.tar
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Exports a Docker container to a tar file.

Import Container 

docker import <file_name>.tar
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Imports a container from a tar file.

5. Docker Save and Load

Save Docker Image 

docker save -o <file_name>.tar <image_name>
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Saves a Docker image to a tar file.

Load Docker Image 

docker load -i <file_name>.tar
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Loads a Docker image from a tar file.

6. Docker Prune

Remove Unused Data 

docker system prune
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Removes unused Docker data (images, containers, networks, volumes).

7. Docker Context

List Docker Contexts 

docker context ls
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Lists all Docker contexts.

Create Docker Context 

docker context create <context_name>
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Creates a new Docker context.

Use Docker Context 

docker context use <context_name>
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Switches to a specific Docker context.

8. Docker BuildKit

Enable BuildKit 

export DOCKER_BUILDKIT=1
docker build -t <image_name> .
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Enables Docker BuildKit for improved build performance.

📊 Best Practices

Use Version Control

  • Store your Dockerfiles, Compose files, and other configurations in a version control system (e.g., Git) to track changes and collaborate with team members.

Keep Images Lightweight

  • Minimize the size of your Docker images by using multi-stage builds and removing unnecessary files and dependencies.

Use Tags

  • Tag your Docker images with meaningful and version-specific tags to easily identify and manage them.

Secure Images and Containers

  • Scan your Docker images for vulnerabilities and use security best practices to protect your containers.

Automate Builds and Deployments

  • Integrate Docker with CI/CD pipelines to automate the building, testing, and deployment of your containerized applications.

Monitor and Log

  • Continuously monitor your Docker containers and collect logs for troubleshooting and performance analysis.

Use Docker Compose for Multi-Container Applications

  • Use Docker Compose to define and manage multi-container applications, making it easier to deploy and scale your services.

Regularly Prune Unused Resources

  • Regularly prune unused images, containers, networks, and volumes to free up disk space and maintain a clean Docker environment.

🚀 Conclusion

Mastering Docker commands, from beginner to advanced levels, is essential for DevOps engineers to manage and automate containerized applications effectively. This comprehensive guide serves as a valuable reference for navigating your Docker environment. By following best practices and leveraging these commands, you can ensure a robust and efficient container orchestration setup.

Happy Dockerizing! 🎉

Thank you for reading my blog …:)

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Top comments (20)

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bobbyiliev profile image
Bobby Iliev •

Great post! Well done 👏

I've shared this on Daily Dev as well:

app.daily.dev/posts/3aNFSERaZ

Also for anyone who wants to learn more here is a free ebook:

GitHub logo bobbyiliev / introduction-to-docker-ebook

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The guide is suitable for anyone working as a developer, system administrator, or a DevOps engineer and wants to learn the basics of Docker.

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View on GitHub
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notharshhaa profile image
H A R S H H A A •

Thank you @bobbyiliev for your feedback 🌟

Thank you again for adding this insight—it's a great addition to the discussion on Docker! 🙌

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tokologo1 profile image
TKMshengu •

Awesomes

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notharshhaa profile image
H A R S H H A A •

Thank you @tokologo1 for your feedback 🌟

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dun_huang_a8b05c1e8b15783 profile image
Dun Huang •

Good !!

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notharshhaa profile image
H A R S H H A A •

Thank you @dun_huang_a8b05c1e8b15783 for your feedback 🌟

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hectorlaris profile image
Héctor Serrano •

Thank you, so useful.

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notharshhaa profile image
H A R S H H A A •

Thanks 😊👍 @hectorlaris

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jangelodev profile image
João Angelo •

Hi H A R S H H A A,
Top, very nice and helpful !
Thanks for sharing.

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notharshhaa profile image
H A R S H H A A •

Thank you @jangelodev for your feedback 🌟

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sc0v0ne profile image
sc0v0ne •

I really liked the post, simple and straight to the point.

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notharshhaa profile image
H A R S H H A A •

Thank you @sc0v0ne for your feedback 🌟

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nyangweso profile image
Rodgers Nyangweso •

awesome

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notharshhaa profile image
H A R S H H A A •

Thank you @nyangweso for your feedback 🌟

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nguyenhailong profile image
NGUYEN LONG •

Verry helpful for beginers like me.
Thanks u so much .

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notharshhaa profile image
H A R S H H A A •

Thanks 😊👍 @nguyenhailong

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