# 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](https://www.docker.com/)
Documentation: [Docker Documentation | Docker Documentation](https://docs.docker.com/)

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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/bash` | 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](https://github.com/thedatabaseme/docker_backup).
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-replay`for 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](https://thedatabaseme.de/2022/03/18/shorty-generate-docker-run-commands-using-docker-replay/).

### 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"`
## Networks

## Troubleshooting
### Networking
`docker run --name netshoot --rm -it nicolaka/netshoot /bin/bash`