Docker

Docker is a set of platform as a service (PaaS) products that use OS-level virtualization to deliver software in packages called containers. The service has both free and premium tiers. The software that hosts the containers is called Docker Engine.

Project Homepage: Home - Docker Documentation: Docker Documentation | Docker Documentation

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Installation

One-click installation script:

curl https://get.docker.com | sh \
  && sudo systemctl --now enable docker

Run docker as non-root user:

sudo groupadd docker
sudo usermod -aG docker $USER

Install Docker Engine: Docker Engine

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Build Images

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Docker CLI

Run Containers

COMMAND	DESCRIPTION
docker run IMAGE	Start a new container
docker run --name CONTAINER IMAGE	Start a new container and set a name
docker run -p HOSTPORT:CONTAINERPORT IMAGE	Start a new container with mapped ports
docker run -P IMAGE	Start a new container and map all ports

Container Management:

COMMAND	DESCRIPTION
docker create IMAGE	Create a new container
docker start CONTAINER	Start a container
docker stop CONTAINER	Graceful stop a container
docker kill CONTAINER	Kill (SIGKILL) a container
docker restart CONTAINER	Graceful stop and restart a container
docker pause CONTAINER	Suspend a container
docker unpause CONTAINER	Resume a container
docker rm CONTAINER	Destroy a container

Container Bulk Management

COMMAND	DESCRIPTION
docker stop $(docker ps -q)	To stop all the running containers
docker stop $(docker ps -a -q)	To stop all the stopped and running containers
docker kill $(docker ps -q)	To kill all the running containers
docker kill $(docker ps -a -q)	To kill all the stopped and running containers
docker restart $(docker ps -q)	To restart all running containers
docker restart $(docker ps -a -q)	To restart all the stopped and running containers
docker rm $(docker ps -q)	To destroy all running containers
docker rm $(docker ps -a -q)	To destroy all the stopped and running containers
docker pause $(docker ps -q)	To pause all running containers
docker pause $(docker ps -a -q)	To pause all the stopped and running containers
docker start $(docker ps -q)	To start all running containers
docker start $(docker ps -a -q)	To start all the stopped and running containers
docker rm -vf $(docker ps -a -q)	To delete all containers including its volumes use
docker rmi -f $(docker images -a -q)	To delete all the images
docker system prune	To delete all dangling and unused images, containers, cache and volumes
docker system prune -a	To delete all used and unused images
docker system prune --volumes	To delete all docker volumes

Inspect Containers:

COMMAND	DESCRIPTION
docker ps	List running containers
docker ps -a	List all containers, including stopped
docker logs CONTAINER	Show a container output
docker logs -f CONTAINER	Follow a container output
docker top CONTAINER	List the processes running in a container
docker diff	Show the differences with the image (modified files)
docker inspect	Show information of a container (json formatted)

Run Commands:

COMMAND	DESCRIPTION
docker attach CONTAINER	Attach to a container
docker cp CONTAINER:PATH HOSTPATH	Copy files from the container
docker cp HOSTPATH CONTAINER:PATH	Copy files into the container
docker export CONTAINER	Export the content of the container (tar archive)
docker exec CONTAINER	Run a command inside a container
docker exec -it CONTAINER /bin/shell	Open an interactive shell inside a container (there is no bash in some images, use /bin/sh)
docker wait CONTAINER	Wait until the container terminates and return the exit code

Images:

COMMAND	DESCRIPTION
docker images	List all local images
docker history IMAGE	Show the image history
docker inspect IMAGE	Show information (json formatted)
docker tag IMAGE TAG	Tag an image
docker commit CONTAINER IMAGE	Create an image (from a container)
docker import URL	Create an image (from a tarball)
docker rmi IMAGE	Delete images
docker pull REPO:[TAG]	pull an image/repo from a registry
docker push REPO:[TAG]	push and image/repo to a registry
docker search TEXT	Search an image on the official registry
docker login	Login to a registry
docker logout	Logout from a registry
docker save REPO:[TAG]	Export an image/repo as a tarball
docker load	Load images from a tarball

Volumes:

COMMAND	DESCRIPTION
docker volume ls	List all vol1umes
docker volume create VOLUME	Create a volume
docker volume inspect VOLUME	Show information (json formatted)
docker volume rm VOLUME	Destroy a volume
docker volume ls --filter="dangling=true"	List all dangling volumes (not referenced by any container)
docker volume prune	Delete all volumes (not referenced by any container)

Backup a container

Backup docker data from inside container volumes and package it in a tarball archive.

docker run --rm --volumes-from CONTAINER -v $(pwd):/backup busybox tar cvfz /backup/backup.tar CONTAINERPATH

An automated backup can be done also by this Ansible playbook. The output is also a (compressed) tar. The playbook can also manage the backup retention. So older backups will get deleted automatically.

To also create and backup the container configuration itself, you can use docker-replayfor that. If you lose the entire container, you can recreate it with the export from docker-replay. A more detailed tutorial on how to use docker-replay can be found here.

Restore container from backup

Restore the volume with a tarball archive.

docker run --rm --volumes-from CONTAINER -v $(pwd):/backup busybox sh -c "cd CONTAINERPATH && tar xvf /backup/backup.tar --strip 1"