Docker Cheatsheet

Docker cheatsheet

If you have any questions, feel free to comment below.

This is a cheatsheet of docker.

Note: the docs will be updated from time to time.

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

docker push <username>/<image_name>
docker images
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.
docker create -it ubuntu:20.04 create a container by the image
docker tag image_name:tag new_image_name:new_tag
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 login -u <username>
docker search <image_name>
docker push <username>/<image_name>
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.

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 (-i means stdio -t means pseudo-tty -d means detach) == pull + create + start
- eg. docker run -p 20000:22 --name my_docker_server -itd docker_images:1.0
- For the -itd effection, you can refer to this blog.
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)

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.