It has been around since 2013, but it is already very popular and used by software developers: Docker is a platform that allows you to create and distribute applications, which is also able to isolate applications in environments called containers. 

These containers are lightweight, portable, and self-sufficient, allowing developers to run their applications more efficiently and reliably.

Let's go into more detail about Docker

In essence, Docker is a containerization tool. Its great advantage is that it can package an application and all the materials related to it into a single container.

This container can run on any operating system that supports Docker. 

This ensures that the application behaves the same regardless of the environment it runs in. This eliminates the classic problem of "it only works on my machine", for example.

What a container looks like in Docker

A Docker container is a lightweight, portable, self-contained unit that contains everything needed to run an application: source code, libraries, dependencies, and configurations. 

Unlike virtual machines, which virtualize an entire operating system, containers share the kernel of the host operating system, but isolate resources at the process level. 

Containers operate through a combination of operating system technologies, including namespace and cgroups of Linux. These mechanisms allow for process isolation and resource management.

For example, the Namespace isolates various aspects of the operating system, such as processes, networking, and file systems. 

Each container has its own namespace, which isolates it from other containers and the host system. 

Instead i Control Groups gThey manage the allocation of resources, such as CPU, memory, and I/O, ensuring that a container does not consume all the system resources.

Why use Docker

Adopting Docker containers brings numerous benefits to the software development lifecycle:

As mentioned, Docker isolates the application and its dependencies from the underlying operating system, reducing conflicts between versions of libraries and other components. 

Additionally, a Docker container can run on any system that supports Docker.

Another great advantage of containers: they are lightweight and share the operating system kernel, reducing resource consumption compared to traditional virtual machines.

In addition, it simplifies the horizontal scaling of applications, making it easier to manage multiple instances of the application in distributed environments, and above all, as we will see better in the next paragraph, it reduces startup times compared to virtual machines.

Use Docker or Virtual Machines?

At this point it is necessary to make a practical comparison between Docker and virtual machines.

Both provide insulation.

However, VMs run an entire virtualized operating system on a hypervisor, which leads to higher resource usage. 

Docker, on the other hand, uses the host operating system kernel and separates only the applications and their dependencies, making containers much lighter and quicker to launch.

Integrate Docker into your development process

Docker is not just a deployment tool, but can be effectively integrated into every phase of the deployment process. software development.

Using Docker during local development allows developers to work in environments that perfectly mirror production. 

This reduces discrepancies between different environments and speeds up the debugging process.

But Docker can be used to create test environments isolated. 

For example, you can run automated tests inside Docker containers, ensuring that tests run in a consistent, interference-free environment.

In modern Continuous Integration/Continuous Deployment (CI/CD) pipelines, Docker plays a central role. 

Docker images can be automatically built and tested, then deployed into production with confidence that they will work as expected.