Containerization is a modern technology that has drastically transformed the software deployment process. It involves packaging software applications and all their dependencies into a single, self-contained unit known as a container.

So, what is a container?

A container is a package containing all the necessary components required to run an application. It makes it super easy to move your app from one environment to another. You don't have to stress about compatibility issues or anything like that. For instance, a developer can quickly move the app from their laptop to a production server without any hassle.

Here's a concrete example to illustrate this:

Imagine you're developing a web app with Python. You're using a particular version of Python and a set of libraries to run it on your laptop. When it's time to deploy it on a production server, all you need to do is take the container from your laptop and move it to the server. The container bundles all the dependencies, so you can be sure that the app will run the same way on the server as it did on your laptop. This holds true even if the server has different libraries installed or runs a different version of the operating system.

This is a huge advantage over traditional approaches to software deployment. In particular, it eliminates the headache of compatibility issues. With containers, you can rest assured that the application will function as intended, regardless of where you deploy it.

Containers can also be a lifesaver when you have multiple teams working on different parts of an application, each with its own set of dependencies. In this scenario, containers allow you to package your dependencies into separate containers and then integrate them easily into a single application.

By isolating each component in its own self-contained environment, you eliminate the risk of compatibility issues between different parts of the app. Each container can run independently without affecting the functionality of other components. This makes the whole process more streamlined and efficient.

In short, containers provide a simple, reliable way to package and deploy applications. They make it easy to move the applications from one environment to another without any compatibility issues.

Now that you have a good understanding of what containerization is and the problems it solves, let's dive into one of the most popular containerization technologies — Docker.

Docker

Docker is one of the most widely used and well-known containerization technologies. It provides a platform for building, deploying, and running applications in containers.

The key components of the Docker platform are:

• Docker CLI: The Docker CLI (Command Line Interface) is the client-side component of the Docker platform. It is used to create and manage Docker containers.
• Docker Daemon: The Docker Daemon is the server component that implements Docker’s core functionality. It exposes a REST API, which the Docker CLI communicates with. This allows the CLI to perform various actions such as starting, stopping, and listing containers.
• Docker Registry: A Docker registry is a centralized repository for storing and distributing Docker images. You can think of a Docker image as a template or blueprint that contains all the necessary instructions to create a container. By default, Docker is configured to search for images in a public registry called Docker Hub.

Read more: Docker Architecture Explained: Docker Client, Docker Daemon & Docker Registry

Now that we've discussed Docker, you might be wondering how it all works. Specifically, what does the containerization process with Docker look like? Let’s explore that now.

Containerizing Applications With Docker

Containerizing an application with Docker involves several steps:

• Preparing the application code and the dependencies: The first step is to gather the application code, libraries, and any other dependencies the application needs to run.
• Create a Dockerfile: The next step is to create a Dockerfile. It describes the application and tells Docker how to build it into an image. At a high level, the Dockerfile specifies the base image to use, the instructions to install the dependencies, and the command to run the application. It serves as the blueprint for building the container image.
• Build the container Image: After creating the Dockerfile, the next step is to build the container image using the docker build command. This command takes the Dockerfile as input and produces a container image as output. The image created contains all the necessary components to run the application.
• Push the image to a registry: Once the container image is built, it can be pushed to a registry (such as Docker Hub) for sharing and distribution. This allows others to easily download and run the containerized application.
• Run the container: To run the containerized application, the container image is pulled from the registry and run using the docker run command. This creates a new instance of the container that runs the application.
• Share and deploy: Finally, once the application is containerized, it can be easily shared and deployed across different environments, without worrying about compatibility issues or infrastructure dependencies.

If you are looking to jumpstart your Docker journey, our course Docker Training for the Absolute Beginner is a great place to begin.

Now that we've discussed how containerization works with Docker, let's take a look at the benefits of this technology

Benefits of Containerization.

Containerization provides a number of significant benefits, including:

• Portability: Containers provide a way to move applications between different environments with ease. For instance, you can transfer your app from development to production, or from one host operating system to another, without any hassle. Thanks to containerization, you no longer need to worry about compatibility issues.
• Isolation: Containers provide a separate environment for each application and its dependencies. This means that each container runs as an isolated unit on the host operating system. This reduces the risk of conflicts or interference between different applications. Isolation also improves the stability and security of the overall system. By separating applications into isolated environments, you can limit the potential impact of any issues or failures, such as a security breach or a crash. If you want to troubleshoot issues in a specific container, you can do so without affecting other containers or the host operating system.
• Resource efficiency: With containers, when you run multiple applications on the same host system, they share the host’s operating system. This means you don't need to allocate resources to each application individually, as you do with virtual machines. This results in significant cost savings.
• Scalability: Scalability refers to the ability to handle increasing amounts of traffic, and containers make it incredibly easy to scale your applications. For example, let's say you have a web application that's suddenly become very popular. With traditional methods, you would need to manually add more servers to ensure that the app can handle the increased traffic. But with containers, you can simply add more copies of the app in a matter of minutes. This automatically distributes the load across the copies. And if traffic suddenly drops, you can simply remove some of the copies. Containers make it easy to scale up and down, depending on your needs.

Read more: Docker Containerization: Key Benefits and Use Cases

Conclusion

To sum it up, containerization helps us package software applications and their required dependencies into containers. And containers make it easier to deploy applications across different environments.

Docker is the most popular containerization platform to build and manage applications using containers. This all adds up to a better and faster software delivery process and more stable applications.