Docker :

• Docker is a platform for building, running and shipping out applications.

Container	Virtual Machine
An isolated environment for running an application	An abstraction of a machine. (Physical hardware)
Need less hardware resources	Each VM needs a full-blown OS
Start quickly	Slow to start
Allow running multiple apps in isolation	*
Use OS of the host	Resource intensive

Installing Docker container: Linux (Ubuntu 20.04 LTS)

• Updating the Ubuntu package database.

    $ sudo apt-get update

• For silent installation

    $ sudo apt install docker.io -y

• Now that Docker is installed and running you should verify that everything is working okay. This can be done using the hello-world app. From the command line run :

    $ sudo docker run hello-world

• You can also check your docker version by using following commands:

    $ docker version

    Client:
        Version:           20.10.2
        API version:       1.41
        Go version:        go1.13.8
        Git commit:        20.10.2-0ubuntu1~20.04.2
        Built:             Tue Mar 30 21:24:57 2021
        OS/Arch:           linux/amd64
        Context:           default
        Experimental:      true

    Server:
        Engine:
        Version:          20.10.2
        API version:      1.41 (minimum version 1.12)
        Go version:       go1.13.8
        Git commit:       20.10.2-0ubuntu1~20.04.2
        Built:            Mon Mar 29 19:10:09 2021
        OS/Arch:          linux/amd64
        Experimental:     false
        containerd:
        Version:          1.3.3-0ubuntu2.3
        GitCommit:
        runc:
        Version:          spec: 1.0.2-dev
        GitCommit:
        docker-init:
        Version:          0.19.0
        GitCommit:

Making Docker start automatically on system boot:

    $ sudo systemctl enable --now docker

Building a Docker container:

    $ docker build -t <REPOSITORY-NAME> <directory>

• For Instance

    $ docker build -t hello-docker .

• Period(.) stands for whole directory of the root project.

For checking list of repositories:

    $ docker images

Running a Docker container:

    $ docker run <REPOSITORY-NAME>

Deleting a Docker container:

    $ docker rmi -f <IMAGE-ID>

Getting an Ubuntu terminal in Docker container:

    $ docker run it ubuntu