A comprehensive Docker cheat sheet for beginners

#day20 of #90daysofDEVOPS

Are you just stepping into the world of Docker and feeling a bit overwhelmed by all the commands and options? Don’t worry; you’re not alone! Docker is a powerful tool for containerization, but it can take some time to get comfortable with its commands and functionalities. To help you along your journey, we’ve put together a comprehensive Docker cheat sheet tailored for beginners. Let’s dive in!

Getting Started

First things first, let’s familiarize ourselves with some basic Docker commands:

docker version: Displays detailed information about your Docker CLI and daemon versions.
docker system info: Lists data about your Docker environment, including active plugins and container/image counts.
docker help: View the help index, a reference of all the supported commands.
docker <command> --help: View detailed information about a particular command.

Building Images

Building images from Dockerfiles is a fundamental aspect of Docker:

docker build .: Build the Dockerfile in your working directory into a new image.
docker build -t example-image:latest .: Build the Dockerfile and tag the resulting image.
docker build -f docker/app-dockerfile: Build a Dockerfile at a specific path.
docker build --build-arg foo=bar .: Set build arguments during the build process.
docker build --pull .: Pull updated versions of images referenced in FROM instructions.
docker build --quiet .: Build an image without emitting output.

Running Containers

Once you have your images, you’ll want to run containers:

docker run example-image:latest: Run a container using a specific image.
docker run -d example-image:latest: Detach terminal from the running container.
docker run -it example-image:latest: Attach terminal's input stream and TTY for interactive commands.
docker run --name my-container example-image:latest: Name the new container.
docker run -p 8080:80 example-image:latest: Bind ports between host and container.
docker run -v /host-directory:/container-directory example-image:latest: Bind mount directories between host and container.
docker run --network my-network example-image:latest: Connect container to a specific network.

Managing Containers

Managing containers is crucial for effective Docker usage:

docker ps: List all running containers.
docker ps -a: List all containers, including stopped ones.
docker attach <container>: Attach terminal to a running container.
docker stop <container>: Stop a running container.
docker rm <container>: Delete a container.

Copying to and from Containers

Copying files to and from containers is made easy with docker cp:

docker cp example.txt my-container:/data: Copy file from host to container.
docker cp my-container:/data/example.txt /demo/example.txt: Copy file from container to host.

Executing Commands in Containers

Run commands inside containers with docker exec:

docker exec my-container demo-command: Run command inside container.
docker exec -it my-container demo-command: Run interactive command inside container.

Accessing Container Logs

Access logs from containers using docker logs:

docker logs <container>: Stream existing log output.
docker logs <container> --follow: Stream new logs continuously.
docker logs <container> -n 10: Get last 10 logs.

Managing Images

Interact with Docker images using these commands:

docker images: List all stored images.
docker rmi <image>: Delete an image.
docker tag <image> example-image:latest: Add a new tag to an existing image.

Pulling and Pushing Images

Push and pull images to/from remote registries:

docker push example.com/user/image:latest: Push image to remote registry.
docker pull example.com/user/image:latest: Pull image from remote registry.