Top Docker Commands Every User Should Master
Posted on September 19, 2024 • 6 min read • 1,277 wordsDiscover the top Docker commands every developer must master, including Docker images, containers, and Docker Compose. Streamline container management and boost productivity with essential tips on docker run, docker pull, docker build, and more
Docker is a powerful tool that simplifies the process of creating, deploying, and managing applications. Mastering its core commands will not only boost your productivity but also enhance the way you work with containers. In this guide, we’ll focus on essential Docker commands, organized into three key areas: Docker Images, Docker Containers, and Docker Compose.
1. Mastering Docker Images
Docker images are the foundation of containers. They are immutable files that contain the code, runtime, libraries, and dependencies needed to run your application. Understanding how to work with Docker images is crucial for efficient containerization.
1. docker pull
The docker pull command fetches an image from a remote registry (such as Docker Hub) to your local machine.
docker pull [IMAGE_NAME]:[TAG]docker pull node:14In this example, Docker pulls version 14 of the Node.js image from Docker Hub.
Why It’s Important: Ensures you’re using the most up-to-date or specific image version.
2. docker images
This command lists all the Docker images available on your local system.
docker imagesKey Details:
- REPOSITORY: The name of the image.
- TAG: The version of the image.
- IMAGE ID: The unique ID of the image.
- SIZE: The disk space the image takes.
Why It’s Important: Helps you manage and track the images you’ve downloaded or built.
3. docker build
When you’re developing your own applications, you’ll need to build images. The docker build command builds an image from a Dockerfile, allowing you to define the environment for your app.
docker build -t [IMAGE_NAME] [PATH_TO_DOCKERFILE]docker build -t myapp .In this case, Docker will search for a Dockerfile in the current directory (.) and create an image named myapp.
Why It’s Important: Allows you to customize and build images tailored to your application needs.
4. docker rmi
The docker rmi command is used to remove images that are no longer needed, freeing up disk space.
docker rmi [IMAGE_NAME]docker rmi node:14Why It’s Important: Regularly removing unused images helps optimize disk space and system performance.
2. Managing Docker Containers
Docker containers are the running instances of Docker images. They encapsulate an application and its dependencies in a consistent environment, ensuring portability across different systems.
1. docker run
The docker run command creates and starts a container from a Docker image. This command is one of the most commonly used in Docker workflows.
docker run [OPTIONS] [IMAGE_NAME]docker run -d -p 8080:80 nginxIn this example, an NGINX server container runs in detached mode (-d), with port 80 of the container mapped to port 8080 on the host.
Key Options:
-d: Runs the container in detached mode (background).-p: Maps container ports to the host.
Why It’s Important: Powers up containers with custom configurations and enables you to map ports and volumes as needed.
2. docker ps
To view the currently running containers, use docker ps. This command provides a list of active containers and details about their status.
docker psWhy It’s Important: Essential for monitoring active containers and diagnosing issues.
3. docker exec
The docker exec command lets you run commands inside a running container. This is especially useful for debugging and making changes on the fly.
docker exec [OPTIONS] [CONTAINER_NAME] [COMMAND]docker exec -it mycontainer bashThis command opens an interactive bash shell (-it) inside the running container mycontainer.
Why It’s Important: Allows real-time interaction with containers, aiding in debugging or runtime modifications.
4. docker stop
The docker stop command gracefully shuts down a running container by sending a SIGTERM signal, allowing it to close processes cleanly.
docker stop [CONTAINER_NAME]docker stop mycontainerWhy It’s Important: Ensures a safe shutdown of running containers without abrupt termination.
5. docker rm
After stopping a container, you can remove it from your system using the docker rm command.
docker rm [CONTAINER_NAME]docker rm mycontainerWhy It’s Important: Removes unused containers to free up resources and maintain a clean environment.
6. docker logs
View the logs generated by a running or stopped container using the docker logs command. This is extremely helpful for diagnosing issues with containerized applications.
docker logs [CONTAINER_NAME]docker logs mycontainerWhy It’s Important: Crucial for monitoring container output, performance, and troubleshooting errors.
3. Orchestrating with Docker Compose
For applications requiring multiple containers (e.g., a web app with a database), managing them individually can be tedious. Docker Compose simplifies this process by using a single YAML file to define, start, and manage multiple containers.
1. docker-compose up
The docker-compose up command brings up all the services (containers) defined in a docker-compose.yml file.
docker-compose up [OPTIONS]docker-compose up -dHere, Docker Compose starts all the services in detached mode (-d).
Why It’s Important: Efficiently spins up complex applications with multiple containers using a single command.
2. docker-compose down
When you’re done working, use docker-compose down to stop and remove all containers, networks, and volumes defined in the Docker Compose file.
docker-compose downWhy It’s Important: Cleanly shuts down all services and removes associated resources, helping maintain a clean environment.
3. docker-compose logs
Similar to docker logs, but for multiple containers, docker-compose logs displays the logs for all services managed by Docker Compose.
docker-compose logs [SERVICE_NAME]docker-compose logs webWhy It’s Important: Allows you to monitor logs for all services in a multi-container application from a single command.
4. Commands reference
1. Docker Images
| Command | Usage | Example |
|---|---|---|
| docker build | docker build [OPTIONS] PATH | URL | - | docker build -t myimage:latest . |
| docker pull | docker pull [OPTIONS] NAME[:TAG | @DIGEST] | docker pull ubuntu:latest |
| docker images | docker images [OPTIONS] [REPOSITORY[:TAG]] | docker images |
| docker rmi | docker rmi [OPTIONS] IMAGE [IMAGE…] | docker rmi myimage:latest |
| docker tag | docker tag SOURCE_IMAGE[:TAG] TARGET_IMAGE[:TAG] | docker tag myimage:latest myrepo/myimage:latest |
| docker save | docker save [OPTIONS] IMAGE [IMAGE…] | docker save -o image_backup.tar myimage:latest |
| docker load | docker load [OPTIONS] | docker load -i image_backup.tar |
| docker history | docker history [OPTIONS] IMAGE | docker history myimage:latest |
| docker inspect | docker inspect [OPTIONS] NAME | ID [NAME | ID…] | docker inspect myimage |
| docker prune | docker image prune [OPTIONS] | docker image prune |
2. Docker Containers
| Command | Usage | Example |
|---|---|---|
| docker run | docker run [OPTIONS] IMAGE [COMMAND] [ARG…] | docker run -d –name my_container nginx |
| docker ps | docker ps [OPTIONS] | docker ps |
| docker stop | docker stop [OPTIONS] CONTAINER [CONTAINER…] | docker stop container_name |
| docker start | docker start [OPTIONS] CONTAINER [CONTAINER…] | docker start container_name |
| docker restart | docker restart [OPTIONS] CONTAINER [CONTAINER…] | docker restart container_name |
| docker exec | docker exec [OPTIONS] CONTAINER COMMAND [ARG…] | docker exec -it container_name bash |
| docker rm | docker rm [OPTIONS] CONTAINER [CONTAINER…] | docker rm container_name |
| docker logs | docker logs [OPTIONS] CONTAINER | docker logs container_name |
| docker inspect | docker inspect [OPTIONS] NAME | ID [NAME | ID…] | docker inspect container_name |
| docker top | docker top CONTAINER [ps OPTIONS] | docker top container_name |
3. Docker Compose
| Command | Usage | Example |
|---|---|---|
| docker-compose up | docker-compose up [options] [SERVICE…] | docker-compose up -d |
| docker-compose down | docker-compose down [options] | docker-compose down -v |
| docker-compose build | docker-compose build [options] [SERVICE…] | docker-compose build service_name |
| docker-compose start | docker-compose start [SERVICE…] | docker-compose start service_name |
| docker-compose stop | docker-compose stop [SERVICE…] | docker-compose stop service_name |
| docker-compose restart | docker-compose restart [SERVICE…] | docker-compose restart service_name |
| docker-compose logs | docker-compose logs [options] [SERVICE…] | docker-compose logs -f service_name |
| docker-compose exec | docker-compose exec [options] SERVICE COMMAND [ARGS…] | docker-compose exec service_name bash |
| docker-compose ps | docker-compose ps [options] [SERVICE…] | docker-compose ps |
| docker-compose config | docker-compose config [options] | docker-compose config |
5. Conclusion
Mastering Docker’s commands for working with images, containers, and Docker Compose is essential for any developer or system administrator. These commands not only streamline your workflow but also help you build, run, and manage applications more effectively. Whether you’re pulling images, orchestrating complex multi-container applications with Docker Compose, or troubleshooting with logs, these commands form the core of Docker’s functionality.