What is Docker ?

Docker is a open-source platform that allows user to build, package and run application inside a container.

How to install Docker in Ubuntu ?

Step 1:

Open the CLI terminal in Ubuntu and run this command to update software repositories.

sudo apt update

Step 2:

Install docker by following command:

sudo apt install docker.io -y

Step 3:

Enable and start docker service

sudo systemctl enable docker --now

Step 4:

Check the docker version

docker --version

How to execute Docker command without sudo ?

To achieve this, we need to add Ubuntu user to the docker group.

docker --versiosudo usermod -aG docker $USER

Now find out current add user is added to the docker group or not

getent group docker

Now refresh the group permission

getent group docknewgrp docker

Now restart docker

sudo service docker restart

How to create images from docker file ?

Build docker image from docker file

suddocker build -t <Name of the Dockerfile>

docker build -t myimg:latest .

Docker basic commands:

Old Commands	New Commands	Purpose
docker ps	docker container ls	List containers
docker run	docker container run	Run a command in a new container
docker rm	docker container rm	Remove one or more containers
docker images	docker image ls	List images
docker rmi	docker image rm	Remove one or more images

How to list all pulled images?

docker images

How to map port on a host?

docker run -p -d 8080:8080 ubuntu

How to login docker, build and push?

login:

docker login

build:

docker lodocker build -t image_name:tag .

push:

docker push <Image name/Image ID>

How to stop docker single container and multiple containers?

docker stop container_name_or_id

docker stop container1 container2 container3

How to restart and inspect docker ?

restart:

docker sdocker restart container_name_or_id

inspect:

docker inspect container_name_or_id

What is docker hub?

It is a cloud based registry for docker images. It contains vast repository of public images and official images for popular applications and services.

What is docker image?

It is a virtual template which is used to create containers, it is includes everything which are need to run an application such as OS, application code, libraries, dependencies. A docker file has a set of scripts or instructions which specify dependencies, environment variables etc and by a “docker build command”, user can create a docker image.

What is docker compose ?

Docker compose is a multi container managing tool. It is uses YAML file. With docker compose, user can start, stop and all other services with single command.