Docker Cheatsheet

The article will be updated from time to time, feel free to check the latest revision: Docker Cheatsheet

Deamon

• docker info
• systemctl start | stop | restart | status | enable docker This command to operate the docker daemon. For more details, you can refer to the systemd.
• docker system df query the disk usage of the docker

images

1. docker push <username>/<image_name>
2. docker images
3. docker pull | inspect | rmi ubuntu:20.04
   • normally, the image name is composed by registry/username/repository:tag, if there is no username, the default is library, which is the official repository. if there is no registry, the default is docker.io, which is the official registry.
4. docker create -it ubuntu:20.04 create a container by the image
5. docker tag image_name:tag new_image_name:new_tag
6. docker export/import and docker save/load：

• export/import will discard history and metadata information, only saving the snapshot state of the container at the time
  • docker export -o xxx.tar CONTAINER
  • docker import xxx.tar image_name:tag
• save/load will save the complete record, with a larger volume
  • docker save -o xxx.tar image_name:tag
  • docker load -i xxx.tar

docker hub

1. docker login -u <username>
2. docker search <image_name>
3. docker push <username>/<image_name>
4. dangling image: if the image is updated by official, and the tag is allocated to the new image, the old image will be called dangling image. Only display <none> in the docker images command.

containers

• docker ps -a list all containers
• docker ps list running containers
• docker stats search all the containers resource usage (CPU, memory, storage, network)
• docker rename CONTAINER1 CONTAINER2
• docker start | stop | restart | rm | top | inspect | kill ｜ port | history CONTAINER
• docker run -itd ubuntu:20.04 search and run a container (-d means detach) == pull + create + start
  • eg. docker run -p 20000:22 --name my_docker_server -itd docker_images:1.0
• docker attach CONTAINER
  • ⌃ + p and ⌃ + q which can detach the container
  • ⌃+d which can close and exit the container（exit; then the container will be stopped）
• docker logs -f CONTAINER -f means follow, you can see the logs in real time
• docker cp xxx CONTAINER:xxx
• docker exec CONTAINER COMMAND
  • eg docker exec -it container_name bash
  • docker exec -it container_name /bin/bash if your garrison program is sshd(which is not accept input) not the bash, then you should use this command to substitute it. (Recommend, exit; the container will not be stopped)
  • You can also use docker run -it container_name /bin/bash specific the shell to enter the container.
• docker update CONTAINER --memory 500MB
• docker container prune remove all stopped containers
• docker commit container_name image_name:tag Package the container as an image.(Not recommend use to build image, can use as a snapshot of the container)

Docker volume

The volume will not be deleted when the container is deleted. Volume can be shared between containers.

• docker volume create VOLUME create a volume
  • docker run --mount source=VOLUME,target=/webapp option to specify the volume
• docker volume ls list all volumes
• docker volume rm VOLUME remove the volume
• docker volume prune remove all unused volumes
• docker volume inspect VOLUME inspect the volume
• docker rm -v CONTAINER remove the container and the volume

Besides, you can also mount the host directory to the container. The host directory path must be absolute path.

docker run -d -P \
    --name web \
    --mount type=bind,source=/src/webapp,target=/opt/webapp[,readonly] \
    training/webapp \
    python app.py

For the detail of build docker image, you can refer to the tips about dockerfile.