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Devang Tomar
Devang Tomar

Posted on • Originally published at devangtomar.Medium on

TOP Docker commands (with examples) that you should know

#commands #dockerintroduction #commandlineinterface #dockerfiles

Docker is an open platform for app development, shipping, and running. Docker allows you to decouple your apps from your infrastructure, allowing you to release software more quickly. Docker allows you to package and run an application in a container, which is a loosely isolated environment. The Docker container trend is unstoppable, with firms actively seeking people that are well-versed in Docker commands.

1. Docker Registries & Repositories

Login to a Registry 

docker login docker login localhost:8080
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Logout from a Registry 

docker logout docker logout localhost:8080
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Searching an Image 

docker search nginx docker search --filter stars=3 --no-trunc nginx
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Pulling an Image 

docker image pull nginx docker image pull devangtomar/nginx localhost:5000/myadmin/nginx
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Pushing an Image 

docker image push devangtomar/nginx docker image push devangtomar/nginx localhost:5000/myadmin/nginx
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2. 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
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Creating a Container 

docker container create -t -i devangtomar/infinite — name infinite
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Running a Container 

docker container run -it — name infinite -d devangtomar/infinite
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Renaming a Container 

docker container rename infinite infinity
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Removing a Container 

docker container rm infinite
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A container can be removed only after stopping it using 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
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Running a command within a running container 

docker exec -it infinite sh
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In the example above, bash can replace sh as an alternative (if the above is giving an error).

3. Starting & Stopping Containers

Starting 

docker container start nginx
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Stopping 

docker container stop nginx
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Restarting 

docker container restart nginx
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Pausing 

docker container pause nginx
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Unpausing 

docker container unpause nginx
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Blocking a Container 

docker container wait nginx
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Sending a SIGKILL 

docker container kill nginx
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Sending another signal 

docker container kill -s HUP nginx
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Connecting to an Existing Container 

docker container attach nginx
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4. Getting Information about Containers

From Running Containers

Shortest way :

docker ps
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Alternative :

docker container ls
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From All containers. 

docker ps -a docker container ls -a
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Container Logs 

docker logs infinite
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‘tail -f’ Containers’ Logs 

docker container logs infinite -f
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Inspecting Containers 

docker container inspect infinite docker container inspect --format ‘{{ .NetworkSettings.IPAddress }}’ $(docker ps -q)
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Containers Events 

docker system events infinite
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Public Ports 

docker container port infinite
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Running Processes 

docker container top infinite
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Container Resource Usage 

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

docker container diff infinite
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5. Managing Images

Listing Images 

docker image ls
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Building Images

From a Dockerfile in the Current Directory

docker build .
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From a Remote GIT Repository

docker build github.com/creack/docker-firefox
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Instead of Specifying a Context, You Can Pass a Single Dockerfile in the URL or Pipe the File in via STDIN 

docker build - < Dockerfile docker build - < context.tar.gz
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Building and Tagging 

docker build -t devangtomar/infinite .
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Building a Dockerfile while Specifying the Build Context 

docker build -f myOtherDockerfile .
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Building from a Remote Dockerfile URI 

curl example.com/remote/Dockerfile | docker build -f — .
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Removing an Image 

docker image rm nginx
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Loading a Tarred Repository from a File or the Standard Input Stream 

docker image load < ubuntu.tar.gz docker image load --input ubuntu.tar
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Saving an Image to a Tar Archive 

docker image save busybox > ubuntu.tar
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Showing the History of an Image 

docker image history
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Creating an Image From a Container 

docker container commit nginx
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Tagging an Image 

docker image tag nginx devangtomar/nginx
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Pushing an Image 

docker image push devangtomar/nginx
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6. Networking

Creating Networks

  • Creating an Overlay Network 
docker network create -d overlay MyOverlayNetwork
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  • Creating a Bridge Network 
docker network create -d bridge MyBridgeNetwork
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  • Creating a Customized Overlay Network 
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
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Removing a Network 

docker network rm MyOverlayNetwork
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Listing Networks 

docker network ls
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Getting Information About a Network 

docker network inspect MyOverlayNetwork
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Connecting a Running Container to a Network 

docker network connect MyOverlayNetwork nginx
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Connecting a Container to a Network When it Starts 

docker container run -it -d — network=MyOverlayNetwork nginx
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Disconnecting a Container from a Network 

docker network disconnect MyOverlayNetwork nginx
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Exposing Ports

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

EXPOSE <port_number>
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You can also map the container port to a host port using :

docker run -p $HOST_PORT:$CONTAINER_PORT — name -t <image>
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e.g.

docker run -p $HOST_PORT:$CONTAINER_PORT — name infinite -t infinite
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7. 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

8. Cleaning Docker

Removing a Running Container 

docker container rm nginx
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Removing a Container and its Volume 

docker container rm -v nginx
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Removing all Exited Containers 

docker container rm $(docker container ls -a -f status=exited -q)
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Removing All Stopped Containers 

docker container rm `docker container ls -a -q`
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Removing a Docker Image 

docker image rm nginx
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Removing Dangling Images 

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

docker image rm $(docker image ls -a -q)
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Removing all Untagged Images 

docker image rm -f $(docker image ls | grep “^” | awk “{print $3}”)
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Stopping & Removing all Containers 

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

docker volume rm $(docker volume ls -f dangling=true -q)
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Removing all unused (containers, images, networks and volumes) 

docker system prune -f
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Clean all 

docker system prune -a
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Devang Tomar •

URL of a Hashnode post (with table of content for ease to locate stuff) :

TOP Docker commands (with examples) that you should know 💻

Docker is an open platform for app development, shipping, and running. Docker allows you to decouple your apps from your infrastructure, allowing you to release software more quickly. Docker allows you to package and run an application in a container...

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