Docker Cheat Sheet

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Table of Contents

• Installation
• Docker Registries & Repositories
• Running Containers
• Starting & Stopping Containers
• Getting Information about Containers
• Networking
• Security
• Cleaning Docker
• Docker Swarm
• Notes

Installation

Linux

For more information, see here

curl -sSL https://get.docker.com/ | sh

Mac

For more information, see here

Use this link to download the dmg.

https://download.docker.com/mac/stable/Docker.dmg

Windows

For more information, see here

Use the msi installer:

https://download.docker.com/win/stable/InstallDocker.msi

Docker Registries & Repositories

Login to a Registry

docker login

docker login localhost:8080

Logout from a Registry.

docker logout

docker logout localhost:8080

Searching an Image

docker search nginx

docker search --filter stars=3 --no-trunc nginx

Pulling an Image

docker image pull nginx

docker image pull eon01/nginx localhost:5000/myadmin/nginx

Pushing an Image

docker image push eon01/nginx

docker image push eon01/nginx localhost:5000/myadmin/nginx

Running Containers

Create and Run a Simple Container

• Start an ubuntu:latest image
• Bind the port 80 from the CONTAINER to port 3000 on the HOST
• Mount the current directory to /data on the CONTAINER
• Note: on windows you have to change -v ${PWD}:/data to -v "C:\Data":/data

docker container run --name infinite -it -p 3000:80 -v ${PWD}:/data ubuntu:latest

Creating a Container

docker container create -t -i eon01/infinite --name infinite

Running a Container

docker container run -it --name infinite -d eon01/infinite

Renaming a Container

docker container rename infinite infinity

Removing a Container

docker container rm infinite

A container can be removed only after it has been stopped using the docker stop command. To avoid this, add the --rm flag while running the container.

Updating a Container

docker container update --cpu-shares 512 -m 300M infinite

Running a command within a running container

docker exec -it infinite sh

In the example above, bash can replace sh as an alternative if the above is giving an error.

Starting & Stopping Containers

Starting

docker container start nginx

Stopping

docker container stop nginx

Restarting

docker container restart nginx

Pausing

docker container pause nginx

Unpausing

docker container unpause nginx

Blocking a Container

docker container wait nginx

Sending a SIGKILL

docker container kill nginx

Sending another signal

docker container kill -s HUP nginx

Connecting to an Existing Container

docker container attach nginx

Getting Information about Containers

Running Containers

Shortest way:

docker ps

Alternative:

docker container ls

All containers.

docker ps -a

docker container ls -a

Container Logs

docker logs infinite

Follow Container Logs

docker container logs infinite -f

Inspecting Containers

docker container inspect infinite

docker container inspect --format '{{ .NetworkSettings.IPAddress }}' $(docker ps -q)

Containers Events

docker system events infinite

Public Ports

docker container port infinite

Running Processes

docker container top infinite

Container Resource Usage

docker container stats infinite

Inspecting changes to files or directories on a container’s filesystem

docker container diff infinite

Manipulating Images

Listing Images

docker image ls

Building Images

docker build .

docker build github.com/creack/docker-firefox

docker build - < Dockerfile

docker build - < context.tar.gz

docker build -t eon/infinite .

docker build -f myOtherDockerfile .

curl example.com/remote/Dockerfile | docker build -f - .

Removing an Image

docker image rm nginx

Loading a Tarred Repository from a File or the Standard Input Stream

docker image load < ubuntu.tar.gz

docker image load --input ubuntu.tar

Save an Image to a Tar Archive

docker image save busybox > ubuntu.tar

Showing the History of an Image

docker image history

Creating an Image From a Container

docker container commit nginx

Tagging an Image

docker image tag nginx eon01/nginx

Pushing an Image

docker image push eon01/nginx

Networking

Creating Networks

docker network create -d overlay MyOverlayNetwork

docker network create -d bridge MyBridgeNetwork

docker network create -d overlay \
  --subnet=192.168.0.0/16 \
  --subnet=192.170.0.0/16 \
  --gateway=192.168.0.100 \
  --gateway=192.170.0.100 \
  --ip-range=192.168.1.0/24 \
  --aux-address="my-router=192.168.1.5" --aux-address="my-switch=192.168.1.6" \
  --aux-address="my-printer=192.170.1.5" --aux-address="my-nas=192.170.1.6" \
  MyOverlayNetwork

Removing a Network

docker network rm MyOverlayNetwork

Listing Networks

docker network ls

Getting Information About a Network

docker network inspect MyOverlayNetwork

Connecting a Running Container to a Network

docker network connect MyOverlayNetwork nginx

Connecting a Container to a Network When it Starts

docker container run -it -d --network=MyOverlayNetwork nginx

Disconnecting a Container from a Network

docker network disconnect MyOverlayNetwork nginx

Exposing Ports

Using Dockerfile, you can expose a port on the container using:

EXPOSE <port_number>

You can also map the container port to a host port using:

docker run -p $HOST_PORT:$CONTAINER_PORT –name <container_name> -t

e.g.

docker run -p $HOST_PORT:$CONTAINER_PORT --name infinite -t infinite

Security

Guidelines for building secure Docker images

1. Prefer minimal base images
2. Dedicated user on the image as the least privileged user
3. Sign and verify images to mitigate MITM attacks
4. Find, fix and monitor for open source vulnerabilities
5. Don’t leak sensitive information to docker images
6. Use fixed tags for immutability
7. Use COPY instead of ADD
8. Use labels for metadata
9. Use multi-stage builds for small secure images
10. Use a linter

More detailed information on Snyk’s 10 Docker Image Security Best Practices blog

Cleaning Docker

Removing a Running Container

docker container rm nginx

Removing a Container and its Volume

docker container rm -v nginx

Removing all Exited Containers

docker container rm $(docker container ls -a -f status=exited -q)

Removing All Stopped Containers

docker container rm `docker container ls -a -q`

Removing a Docker Image

docker image rm nginx

Removing Dangling Images

docker image rm $(docker image ls -f dangling=true -q)

Removing all Images

docker image rm $(docker image ls -a -q)

Removing all untagged images

docker image rm -f $(docker image ls | grep "^<none>" | awk "{print $3}")

Stopping & Removing all Containers

docker container stop $(docker container ls -a -q) && docker container rm $(docker container ls -a -q)

Removing Dangling Volumes

docker volume rm $(docker volume ls -f dangling=true -q)

Removing all unused (containers, images, networks and volumes)

docker system prune -f

Clean all

docker system prune -a

Docker Swarm

Installing Docker Swarm

curl -ssl https://get.docker.com | bash

Initializing the Swarm

docker swarm init --advertise-addr 192.168.10.1

Getting a Worker to Join the Swarm

docker swarm join-token worker

Getting a Manager to Join the Swarm

docker swarm join-token manager

Listing Services

docker service ls

Listing nodes

docker node ls

Creating a Service

docker service create --name vote -p 8080:80 instavote/vote

Listing Swarm Tasks

docker service ps

Scaling a Service

docker service scale vote=3

Updating a Service

docker service update --image instavote/vote:movies vote

docker service update --force --update-parallelism 1 --update-delay 30s nginx

docker service update --update-parallelism 5--update-delay 2s --image instavote/vote:indent vote

docker service update --limit-cpu 2 nginx

docker service update --replicas=5 nginx

Notes

This work was first published in Painless Docker Course