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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 …:)

© Copyrights: ProDevOpsGuy

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Top comments (17)

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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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💡 Introduction to Docker

This is an open-source introduction to Docker guide that will help you learn the basics of Docker and how to start using containers for your SysOps, DevOps, and Dev projects. No matter if you are a DevOps/SysOps engineer, developer, or just a Linux enthusiast, you will most likely have to use Docker at some point in your career.

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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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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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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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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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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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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nguyenhailong profile image
NGUYEN LONG •

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

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