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Introduction 👋

  • Docker has rapidly become the de facto standard for containerizing applications. As a developer or DevOps Engineer/SysAdmin, getting familiar with Docker is crucial for deploying modern, portable applications efficiently.
  • While Docker boasts numerous advanced features and commands, there are certain essential ones you'll find yourself using consistently on a daily basis.
  • In this post, we will go through the top 20+ essential Docker commands and their use cases everyone should know.

Installation 🔨

  • To install Docker on your machine, follow this document (Supported various platforms)
  • To get hands-on experience and understand Docker better, you could visit this repository

Table of Contents 🔖

Docker General Commands

1. docker info

  • docker info displays system-wide information
  • Syntax: docker info

2. docker --help

  • docker --help gets help with Docker. Can also use --help on all subcommands
  • Syntax: docker <subcommands> --help

Docker Registry

3. docker login

  • docker login is used to log in to a Docker registry. If no server is specified, the default is defined by the daemon.
  • Syntax: docker login <options> <registry>
  • Use cases:
ID Command Description
1 docker login Log in to the default Docker registry
2 docker login myRegistry -u username Log in to a specified registry with the specified username

4. docker logout

  • To log out from a Docker registry, use docker logout. This command is used when you want to remove the credentials used to authenticate with a registry.
  • Syntax: docker logout <registry_url>
  • Use cases:
ID Command Description
1 docker logout Log out from the default Docker registry
2 docker logout myRegistry Logout from a specified registry

Docker Images

5. docker build

  • docker build is used to build custom Docker images from a Dockerfile.
  • Syntax:docker build -t <your_image_name> <options> <dockerfile_path>
  • Use cases:
ID Command Description
1 docker build -t myImage . Build an image using a Dockerfile in the current directory
2 docker build -t myImage:v0.1.0 . Build a Docker image from a Dockerfile with specified tag
3 docker build -t myImage -f demo/Dockerfile Build an image using a Dockerfile in the demo directory

6. docker tag

  • docker tag allows you to create a new tag for an existing Docker image.
  • Syntax: docker tag <source_image> <target_image>
  • Use cases:
ID Command Description
1 docker tag myImage:latest myImage:v2 Create a new tag "v2" for the Docker image "myImage" with tag "latest"
2 docker tag myImage:latest myRegistry/myImage Tag the Docker image "myImage" with tag "latest" to a registry image tag latest
3 docker tag myImage:latest myRegistry/myImage:1.0.0 Tag the Docker image "myImage" with tag "latest" to a registry image tag 1.0.0

7. docker images

  • The docker images command lists all Docker images pulled and built on your system. You'll use this frequently to view images before running containers or cleaning up.
  • Syntax: docker images <options>
  • Use cases:
ID Command Description
1 docker images List all Docker images on the system
2 docker images -a List all Docker images, including intermediate ones

8. docker pull

  • To download an image from a registry like Docker Hub, use docker pull. For example, docker pull nginx fetches the latest nginx image.
  • Syntax: docker pull <image_name>
  • Use cases:
ID Command Description
1 docker pull nginx Pull the latest nginx image from Docker Hub
2 docker pull nginx:latest Pull the latest nginx image from Docker Hub explicitly
3 docker pull myRegistry/myImage:tag Pull a specific image from a private registry

9. docker push

  • docker push is used to upload Docker images to a registry.
  • Syntax: docker push <image_name>
  • Use cases:
ID Command Description
1 docker push myImage Push the "myImage" image to the default registry
2 docker push myRegistry/myImage:tag Push a specific tagged version of the "myImage" image to a private registry

10. docker save

  • To save a Docker image to a .tar file, use docker save. This command allows you to export an image from your local Docker environment into a portable format.
  • Syntax: docker save -o <output_file> <image_name>
  • Use cases:
ID Command Description
1 docker save -o myImage.tar myImage Save a Docker image to a local .tar file
2 docker save -o /path/to/output.tar myImage Save an image to a specific location on your system

11. docker load

  • To load an image from a saved archive, use docker load. This command is handy when you have an image saved as a .tar file and want to import it into your local Docker environment.
  • Syntax: docker load -i <path_to_image_archive>
  • Use cases:
ID Command Description
1 docker load -i myImage.tar Load a Docker image from a local .tar file
2 docker load -i /path/to/image_archive.tar Load an image from a specific location on your system

12. docker rmi

  • docker rmi removes one or more Docker images. Make sure there are no stopped containers based on an image before removing it.
  • Syntax: docker rmi <image_name>
  • Use cases:
ID Command Description
1 docker rmi myImage Remove the Docker image named "myImage"
2 docker rmi myImage:tag Remove a specific tagged version of the "myImage" image

Docker Container

13. docker run

  • docker run creates and starts a new container from an image. You can pass various options to configure the container's networking, set environment variables, map volumes, and more.
  • Syntax: docker run <options> <image>
  • Use cases:
ID Command Description
1 docker run -d --name mycontainer nginx Run nginx image in detached mode with container name "mycontainer"
2 docker run -p 8080:80 --name mycontainer nginx Run nginx image with port mapping from host 8080 to container 80
3 docker run -e MYSQL_ROOT_PASSWORD=password -v /mydata:/var/lib/mysql mysql Run MySQL image with setting root password
4 docker run -v /mydata:/var/lib/mysql mysql Run MySQL image and mounting a host directory to container
5 docker run --network=host myImage Run a container using the host network
6 docker run --privileged myImage Run a container with extended privileges using the Docker image "myImage"
7 docker run -it myImage /bin/bash Run an image and open a bash shell inside a container

14. docker ps

  • Once you have containers running, you'll need docker ps to list them. The basic docker ps shows just running containers. Use docker ps -a to include stopped containers as well.
  • Syntax: docker ps <options>
  • Use cases:
ID Command Description
1 docker ps List running containers
2 docker ps -a List all containers, including stopped ones

15. docker stop/start/restart

  • These commands allow you to stop, start, or restart one or more running containers. You reference containers by name or ID.
  • Syntax: docker stop/start/restart <container_name>
  • Use cases:
ID Command Description
1 docker stop mycontainer Stop a running container named "mycontainer"
2 docker restart mycontainer Restart a container named "mycontainer"
3 docker start mycontainer Start a stopped container named "mycontainer"

16. docker rm

  • Once you've stopped a container, docker rm removes it entirely from your system. Use docker rm -f to force-remove running containers.
  • Syntax: docker rm <options> <container>
  • Use cases:
ID Command Description
1 docker rm mycontainer Remove a stopped container named "mycontainer"
2 docker rm -f mycontainer Force-remove a running container named "mycontainer"

17. docker logs

  • When a containerized application is not behaving correctly, docker logs retrieves the logs from a specified container to help troubleshoot.
  • Syntax: docker logs <options> <container>
  • Use cases:
ID Command Description
1 docker logs mycontainer Retrieve logs from a container named "mycontainer"
2 docker logs --tail 100 mycontainer Retrieve last 100 lines of logs from "mycontainer"

18. docker exec

  • docker exec allows you to run a new command inside an already-running container. For example, starting a Bash shell with docker exec -it <container> /bin/bash.
  • Syntax: docker exec <options> <container> <command>
  • Use cases:
ID Command Description
1 docker exec -it mycontainer /bin/bash Start an interactive Bash shell in "mycontainer"
2 docker exec mycontainer ls -l /app List files in directory "/app" in "mycontainer"

19. docker cp

  • docker cp allows you to copy files and directories between a container and the local filesystem.
  • Syntax: docker cp <container_id_or_name>:<source_path> <destination_path>
  • Use cases:
ID Command Description
1 docker cp mycontainer:/app/logs/log.txt ./local_dir/ Copy the file "log.txt" from the container "mycontainer" to a local directory
2 docker cp ./local_file.txt mycontainer:/app/data/ Copy the file "local_file.txt" from the local filesystem to the container "mycontainer"

Docker cleanup

20. docker system prune

  • docker system prune allows you to clean up unused data in your Docker environment.
  • Syntax: docker system prune <options>
  • Use cases:
ID Command Description
1 docker system prune Remove all stopped containers, dangling images, and unused networks
2 docker system prune -a Remove all stopped containers, all unused images, and all unused networks

What's next?

Which Docker command do you find yourself using the most? Let us know in the comments below. Your feedback and suggestions are highly appreciated. Thank you, and happy coding! 💖