Docker Tutorial for Beginners

Why Docker?

Every plant of enterprise technology architecture has a number of servers with individual machine or virtual machines in which applications are installed. To make the applications up and running a number of dependencies are installed thru OS patching. Each dependency has to be tracked which is a tedious process.

Also, any other OS patch upgrade which is required for enhancing security, OS performance etc. might break functioning of any existing application in the same infra due to any incompatibility issue or any other changes in the alignment of environment. This creates further issue in bringing down that one faulty system, repairing it and adding it back to the infra specially when there are 100s of servers.

If any server missed out during initial listing for patching also requires repatching in subsequently.

In a complex large-scale infrastructure, getting a downtime for applications to fix issue with that one server is also quite challenging when it impacts up stream and downstream systems which are timebound to process their data.

Thus, regular maintenance to keep the infra up-to-date becomes difficult.

Docker came up with an innovative solution to package together application code, config and support binaries and other OS dependencies, config dependencies and this package is called a Docker image. These images can be deployed in any server as multiple images. And if any of these image gives error; we can just add one more image to the server which is just a replica of the existing images.

Docker Containers are an isolated bunch of processes which runs on the kernel of the host server and has a private set of file system provided by the Docker images. This helps the application to be up and running with a minimal down time. The entire server downtime is not required to fix the issue. Also, the performance of this host server improves as containers takes very less memory like any other discrete process of other executables running on the server. It does not eat up memory like a virtual machine.

Docker Installation Steps

You can install Docker Desktop from the official website of Docker directly in your desktop if it’s a personal one or via a controlled software license and vulnerability assessment platform used in your company for your company machines. Once the installation is done, you can do a sanity check of docker installation using these commands from command prompt:

Docker Version Check

$docker – -version

Docker version 20.01.00 build 432d4d5d3d

Test Docker Installation

You can run hello-world docker image to check this

$docker run hello-world

To show the running image of docker

$docker image ls

To list the hello-world container

$docker ps – -all

To know about various commands used in CLI of Docker please click on the below links: