A Brief Guide about Docker for Developer in 2021

Rohan Mathew


What is Docker?

Docker is a tool for developers to create, deploy and run applications in a separate environment called containers. It is a computer program that performs operating-system-level virtualization, also known as containerization. Docker originated on Linux and not the concept of containerization. You can package an application in a virtual container and run it on any Linux server. 

What is a container, and why do developers need it?

A container packs all application codes and dependencies into a single bundle used in the application. Packaging allows the container to segregate it from the host environment. This abstraction ensures people that an application running under a developing climate can be executed in a production environment without doing certified changes. 

Besides the popularity of Docker, containers have been in discussion for a long time because of their compatibility. After introducing Docker, the ease of use, reliability, and efficiency has compelled the programming world to love this technology. 

What are Dockerfile, Docker Image, and Docker Engine?

Docker comes with its unique language, and three components are being used: Dockerfile, Docker Image, and Docker Engine, which is commonly used while building Docker containers.

  • Docker file comprises a set of instructions to build a Docker image. These instructions will be framed together, one after the other, to create the Docker image. 
  • Docker Image is a template used to make the final Docker container for the application. To create the Docker container, we use the Docker run command and the Docker image. 
  • Docker Engine is the platform where all the framed containers are running on. Both Windows and Linux-based will run on Docker Engine.
  • Docker ToolBox is designed for older versions of Windows, such as Windows 8.1 and Windows 7. Docker ToolBox helps in configuring and launching Docker and even generates an interactive shell for Docker. 

Some important commands for Docker are:

  • -name=” 
  • Docker run -p
  • Docker build
  • Docker images
  • -a -no-trunc=false
  • Docker run -name tracert

How Does It Work?

Docker gives the power to build images for dev work and can be shipped to any cloud provider or even on-premises solution. They take minimal effort, and there we will get so many photos available to start from. 

There may be some problem related to orchestrating all these containers; you can consult 9series for container security solutions. It can make your developing career more convenient, and it can be used to run different environments predictably on your developing machine. 

For development, you can segregate your supporting service containers separately from your application container, and they all can be used on different operating systems and versions while being linked together.

A Fundamental Principle of Docker: 

While changing an image, you cannot change it; for doing changes, you need to create a new image. Unlike a virtual machine where every command may change the starting point of the following command.

Think about a local development tool like Vagrant, which mimics your production server but will help you with your application in a container. The container itself is your build artifact.

How to Dockerize a simple application?

Now, coming to the root cause of all the explanations stated above, how we can dockerize an application. 

First, you need to create a simple Node.js application and then go for Dockerfile, Docker Image and finalize the Docker container for the application.

You need to install Docker on your device and even check and follow the official documentation on your device. To initiate the installation of Docker, you should use an Ubuntu instance. You can use Oracle Virtual Box to set up a virtual Linux instance for that case if you don’t have one already.

Caveat Emptor

Docker containers simplify the API system at runtime; this comes along with the caveat of increased complexity in arranging up containers.

One of the most significant caveats here is Docker and understanding the concern of the system. Many developers treat Docker as a platform for development rather than an excellent optimization and streamlining tool. 

The developers would be better off adopting Platform-as-a-Service (PaaS) systems rather than managing the minutia of self-hosted and managed virtual or logical servers. 

Benefits of using Docker for Development and Operations:

  • Docker is being talked about, and the adoption rate is also quite catchy for some good reason. There are some reasons to get stuck with Docker; we’ll see three: consistency, speed, and isolation. 
  • By consistency here, we mean that Docker provides a consistent environment for your application through production. 
  • If we discuss speed here, you can rapidly run a new process on a server, as the image is preconfigured and is already installed with the process you want it to run.
  • By default, the Docker container is isolated from the network, the file system, and other running processes. 

Docker’s layered file system is one in which Docker tends to add a new layer every time we make a change. As a result, file system layers are cached by reducing repetitive steps during building Docker. Each Docker image is a combination of layers that adds up the layer on every successive change of adding to the picture. 

The Final Words

Docker is not hard to learn, and it’s easy to play and learn. If you ever face any challenges regarding application development, you should consult 9series for docker professional services.