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.
๐ฏ 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.
๐ Beginner Commands
1. Installation
Check Docker Version
docker --version
Displays the installed version of Docker.
2. Docker Images
List Docker Images
docker images
Lists all Docker images on the local machine.
Pull Docker Image
docker pull <image_name>
Pulls a Docker image from a registry (e.g., Docker Hub).
Remove Docker Image
docker rmi <image_name>
Removes a Docker image from the local machine.
3. Docker Containers
List Running Containers
docker ps
Lists all running Docker containers.
List All Containers
docker ps -a
Lists all Docker containers, including stopped ones.
Run a Container
docker run -d --name <container_name> <image_name>
Runs a container from a Docker image in detached mode.
Stop a Container
docker stop <container_name>
Stops a running Docker container.
Start a Container
docker start <container_name>
Starts a stopped Docker container.
Remove a Container
docker rm <container_name>
Removes a Docker container.
View Container Logs
docker logs <container_name>
Displays the logs of a Docker container.
4. Docker Networks
List Docker Networks
docker network ls
Lists all Docker networks.
Create Docker Network
docker network create <network_name>
Creates a new Docker network.
Connect Container to Network
docker network connect <network_name> <container_name>
Connects a container to a Docker network.
Disconnect Container from Network
docker network disconnect <network_name> <container_name>
Disconnects a container from a Docker network.
๐ Intermediate Commands
1. Docker Volumes
List Docker Volumes
docker volume ls
Lists all Docker volumes.
Create Docker Volume
docker volume create <volume_name>
Creates a new Docker volume.
Remove Docker Volume
docker volume rm <volume_name>
Removes a Docker volume.
Mount Volume to Container
docker run -d --name <container_name> -v <volume_name>:/path/in/container <image_name>
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
Installs Docker Compose.
Check Docker Compose Version
docker-compose --version
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
Defines a multi-container application using Docker Compose.
Run Docker Compose
docker-compose up -d
Runs the Docker Compose application in detached mode.
Stop Docker Compose
docker-compose down
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"]
Defines a Dockerfile for a Python application.
Build Docker Image
docker build -t <image_name> .
Builds a Docker image from a Dockerfile.
4. Docker Swarm
Initialize Docker Swarm
docker swarm init
Initializes a Docker Swarm.
List Swarm Nodes
docker node ls
Lists all nodes in the Docker Swarm.
Deploy Stack in Swarm
docker stack deploy -c <compose-file> <stack_name>
Deploys a stack in the Docker Swarm.
Remove Stack from Swarm
docker stack rm <stack_name>
Removes a stack from the Docker Swarm.
5. Docker Secrets
Create Docker Secret
echo "my_secret_value" | docker secret create <secret_name> -
Creates a new Docker secret.
List Docker Secrets
docker secret ls
Lists all Docker secrets.
Remove Docker Secret
docker secret rm <secret_name>
Removes a Docker secret.
๐ง Advanced Commands
1. Docker Inspect
Inspect Docker Container
docker inspect <container_name>
Displays detailed information about a Docker container.
Inspect Docker Image
docker inspect <image_name>
Displays detailed information about a Docker image.
2. Docker Stats
View Container Statistics
docker stats <container_name>
Displays real-time statistics for Docker containers.
3. Docker Events
View Docker Events
docker events
Displays real-time events from the Docker server.
4. Docker Export and Import
Export Container
docker export <container_name> -o <file_name>.tar
Exports a Docker container to a tar file.
Import Container
docker import <file_name>.tar
Imports a container from a tar file.
5. Docker Save and Load
Save Docker Image
docker save -o <file_name>.tar <image_name>
Saves a Docker image to a tar file.
Load Docker Image
docker load -i <file_name>.tar
Loads a Docker image from a tar file.
6. Docker Prune
Remove Unused Data
docker system prune
Removes unused Docker data (images, containers, networks, volumes).
7. Docker Context
List Docker Contexts
docker context ls
Lists all Docker contexts.
Create Docker Context
docker context create <context_name>
Creates a new Docker context.
Use Docker Context
docker context use <context_name>
Switches to a specific Docker context.
8. Docker BuildKit
Enable BuildKit
export DOCKER_BUILDKIT=1
docker build -t <image_name> .
Enables Docker BuildKit for improved build performance.
๐ 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.
๐ 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! ๐
Thank you for reading my blog โฆ:)
ยฉ Copyrights: ProDevOpsGuy
Top comments (20)
Great post! Well done ๐
I've shared this on Daily Dev as well:
Also for anyone who wants to learn more here is a free ebook:
bobbyiliev / introduction-to-docker-ebook
Free Introduction to Docker eBook
๐ก 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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Thanks to these fantastic companies that made this book possible!
Thank you @bobbyiliev for your feedback ๐
Thank you again for adding this insightโit's a great addition to the discussion on Docker! ๐
Awesomes
Thank you @tokologo1 for your feedback ๐
Good !!
Thank you @dun_huang_a8b05c1e8b15783 for your feedback ๐
Thank you, so useful.
Thanks ๐๐ @hectorlaris
Hi H A R S H H A A,
Top, very nice and helpful !
Thanks for sharing.
Thank you @jangelodev for your feedback ๐
I really liked the post, simple and straight to the point.
Thank you @sc0v0ne for your feedback ๐
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Thank you @nyangweso for your feedback ๐
Verry helpful for beginers like me.
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Thanks ๐๐ @nguyenhailong
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