How to Containerize an Application with Docker

Containerizing an application involves packaging it with its dependencies and configuration files. This enables it to run seamlessly in any environment.

This step is crucial in the development process because it allows developers to concentrate on the application itself rather than the environment in which it will operate.

Additionally, it enables the application to deploy in any environment without concerns about dependencies and configurations.

In this article, you’ll learn how to write a Dockerfile to containerize a simple frontend weather application.

Prerequisites

While this tutorial will detail each step, it’s recommended that you have the following:

• Docker installed on your machine. You can find installation instructions for various platforms on the Docker website.
• A fundamental understanding of Docker. If you’re new to Docker, you can explore the Docker Documentation for a quick introduction.

Overview

For simplicity, this tutorial will use a basic weather application. The aim is to learn how to create a Dockerfile – the primary requirement for containerizing an application.

More complex applications will necessitate multiple Dockerfiles, which will introduce Docker Compose and an orchestration tool like Kubernetes. However, these are beyond the scope of this tutorial.

The weather application, named Zeus, is a frontend application utilizing HTML, CSS, and JavaScript to showcase the weather forecast for a specified location.

To containerize an application, you need to create a Dockerfile. A Dockerfile is a text file that contains instructions for building a Docker image.

This Docker image can then be used to create a Docker container which is a running instance of the image.

Figure 1. Workflow for containerizing an application by MrDevSecOps on Medium

The steps below will guide you through the process of creating a Dockerfile for the weather application.