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CheatSheet.md

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Docker CheatSheet

Docker Basics

  • running docker service
docker daemon
  • search for image available by name
docker search $IMAGE_NAME_PART
  • pull a docker image from docker hub
docker pull $IMAGE_NAME_WITH_WITHOUT_VERSION
  • current alive docker instances
docker ps
  • container IDs of current alive docker instances
docker ps -q
  • checking latest created docker instances
docker ps -l

* checking all ran docker instances

docker ps -a


* will download, run and exit

docker run IMAGENAME


* run in interactive mode

docker run -i IMAGENAME


* run with pseudo-tty mode

docker run -t IMAGENAME


* working within docker proper

docker run -it IMAGENAME


* give your name to docker running instances

docker run --name INSTANCE_NAME -it IMAGENAME


* run it in detach mode, useful for service containers

docker run -d IMAGENAME


* start a previously run container by name

docker start $CONTAINER_NAME


* get a quick insight into container state

docker top $CONTAINER_NAME ## like 'top' inside container docker logs $CONTAINER_NAME ## listing logs from container docker stats CONTAINER_NAME ## tap on cpu/mem/network stats used


* attach to detached run

docker attach CONTAINER_ID_FROM_PS


* info on container

docker inspect CONTAINER_ID_FROM_PS


* history of commands run on container

docker history CONTAINER_ID_FROM_PS


* stop a running container

docker stop CONTAINER_ID_FROM_PS docker stop INSTANCE_NAME


* pause/resume/restart a container

docker pause $CONTAINER_NAME docker unpause $CONTAINER_NAME docker restart $CONTAINER_NAME


* save and load an Image to-from tarball

docker save -o $CONTAINER_TARBALL $IMAGE_NAME

docker load -i $CONTAINER_TARBALL


* to kill a docker instance

docker kill CONTAINER_ID_FROM_PS docker kill $(docker ps -q)


* to clean-up instances created for docker run

docker rm CONTAINER_ID_FROM_PS docker rm $(docker ps -aq)


* to delete an image by name

docker rmi $CONTAINER_NAME


* to run command (say 'ls /') within container and spit output

docker exec alpine ls /


---

### Volumes

* it will give you a filesystem inside container
> a volume to live till this container (goes away when removed, not stopped), not shared

docker run -it -v /someVolume alpine


* when you add a file to an image, its copied not referenced

```Dockerfile
FROM alpine
ADD file1 /someVolume/file
VOLUME /someVolume
CMD ["/bin/sh"]
  • to have access to docker host filesystem, will map host's $PWD/myVolume
docker run -it -v $PWD/myVolume:/someVolume alpine
  • to mark mounting host's filesystem as volume READONLY
docker run -it -v $PWD/myVolume:/someVolume:ro alpine

  • can map container bash_history to host file to keep a tab

  • mapping volumes from one container to other, named containers ease else need to fetch name

docker run --name templateImage -it -v $PWD/myVolume:/someVolume alpine
docker run -it --name someImage --volumes-from templateImage alpine
  • is like a shorthand to take backup of mounted volume in templateImage
docker run --rm --volumes-from templateImage -v $(pwd):/backup alpine tar cvf /backup/some.tar /someVolume

Network

  • List port mappings for a container
docker port $CONTAINER_NAME
  • List network artefacts
docker network ls
  • Inspect details of any Network Artefact
docker network inspect $DOCKER_NETWORK_ID

## for all
docker network ls -q | xargs -I '{}' docker network inspect {}
  • can create/remove networks, connect/disconnect containers to a network

Filesystem Level Recon

  • Containers in action
sudo ls /var/lib/docker/containers

The list here will be directory per container named by their ID. These will be containing a log file of history by ID name. JSON config file for image config as 'config.v2.json' and host level details as 'hostconfig.json'. Then more files like 'hosts, 'hostname', 'resolv.conf', etc.

  • Images
sudo ls /var/lib/docker/image
  • Volume
sudo ls /var/lib/docker/volume
  • Network
sudo ls /var/lib/docker/network
  • Devicemapper
sudo ls /var/lib/docker/devicemapper