Top 16 docker commands

• docker ps  list running containers.
• docker ps -a list all container including stopped container
• docker pull  download a image from Docker Hub registry. Link to the docker image is always shown on the right at dockerhub.
• docker build  is used to build your own container based on a Dockerfile. Common use is docker build . to build a container based on the Dockerfile in the current directory (the dot). docker build -t “myimage:latest” . creates a container and stores the image under the given name
• docker images or docker image ls shows all local storage images
• docker run  Run a docker container based on an image, i. e. docker run myimage -it bash. If no local image can be found docker run automatically tries to download the image from Docker hub.
• docker logs display the logs of a container, you specified. To continue showing log updates just use docker logs -f mycontainer
• docker volume ls  lists the volumes, which are commonly used for persisting data of Docker containers.
• docker network ls – list all networks available for docker container
• docker network connect adds the container to the given container network. That enables container communication by simple container name instead of IP.
• docker rm   removes one or more containers. docker rm mycontainer, but make sure the container is not running
• docker rmi removes one or more images. docker rmi myimage, but make sure no running container is based on that image
• docker stop   stops one or more containers. docker stop mycontainer stops one container, while docker stop $(docker ps -a -q) stops all running containers.
• docker start – starts a stopped container using the last state
• docker update –restart=no updates container policies, that is especially helpful when your container is stuck in a crash loop
• docker cp to copy files from a running container to the host or the way around. docker cp :/etc/file . to copy /etc/file to your current directory.
• Some combinations that help a lot:

• kill all running containers with docker kill $(docker ps -q)
• delete all stopped containers with docker rm $(docker ps -a -q)
• delete all images with docker rmi $(docker images -q)
• update and stop a container that is in a crash-loop with docker update –restart=no && docker stop
• bash shell into container docker exec -i -t /bin/bash – if bash is not available use /bin/sh
• bash shell with root if container is running in a different user context docker exec -i -t -u root /bin/bash

What about resource usage

Get docker container including size: docker ps -s

• Get docker container disk utilization: docker system df

What about wasted resources?

The first command is used to remove local container images that are not used by any container and are not tagged. Its a pretty safe command to clean up your local filesystem

docker image prune

If you want to clean up and delete all unused container images, just add -a

• docker image prune -a

only clean up container images that have been created over 24 hours ago run

• docker image prune -a –filter “until=24h“

same can be done with container, that are not running anymore

• docker container prune