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

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 devangtomar/nginx localhost:5000/myadmin/nginx

Pushing an Image

docker image push devangtomar/nginx

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

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

Creating a Container

docker container create -t -i devangtomar/infinite — name infinite

Running a Container

docker container run -it — name infinite -d devangtomar/infinite

Renaming a Container

docker container rename infinite infinity

Removing a Container

docker container rm infinite

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

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).

3. 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

4. Getting Information about Containers

From Running Containers

Shortest way :

docker ps

Alternative :

docker container ls

From All containers.

docker ps -a

docker container ls -a

Container Logs

docker logs infinite

‘tail -f’ Containers’ 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

5. Managing Images

Listing Images

docker image ls

Building Images

From a Dockerfile in the Current Directory

docker build .

From a Remote GIT Repository

docker build github.com/creack/docker-firefox

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

Building and Tagging

docker build -t devangtomar/infinite .

Building a Dockerfile while Specifying the Build Context

docker build -f myOtherDockerfile .

Building from a Remote Dockerfile URI

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

Saving 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 devangtomar/nginx

Pushing an Image

docker image push devangtomar/nginx

6. Networking

Creating Networks

• Creating an Overlay Network

docker network create -d overlay MyOverlayNetwork

• Creating a Bridge Network

docker network create -d bridge MyBridgeNetwork

• 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

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 -t <image>

e.g.

docker run -p $HOST\_PORT:$CONTAINER\_PORT — name infinite -t infinite

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

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 “^” | 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

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