Since its launch in 2012, Docker has become one of the fastest-growing technologies in web application development. But what exactly is Docker?

What is Docker?

Docker is an open source project that provides an abstraction and virtualization layer at the operating system level, through the installation of software containers.

How does Docker work?

Docker was developed based on the original Linux container technology commonly known as LXC. LXC is an operating system-level virtualization method for running multiple operating systems on a single host. This is made possible by namespaces and cgroups.

Docker works with images and containers. An image is a package that includes everything a particular technology needs to function. Images are initialized in one or more instances called containers.

Docker containers vs. virtual machines.

Although they resemble classic VMs, the fundamental difference is that virtual machines require the "Hypervisor" component, which is the monitor that allows the use of different operating systems on the same PC.

Docker containers' decision not to use this component results in performance savings and a lighter system than virtual machines. Thanks to Docker's low cost, we can use a single machine with multiple containers to have separate environments for the same application—development, testing, and production—directly reducing costs.

Container Creation, Execution, and Monitoring

Once Docker is installed, you can use its commands, including:

• Create containersTo launch a Docker container, you need to create a container image. Each container image is based on a file Dockerfile, which Docker uses to launch an instance of your application inside the container. The command docker build generates an image of the container based on Dockerfile. Below is an example of the content of a Dockerfile:

FROM ubuntu:14.04

RUN apt-get update

RUN apt-get install -y python

CMD [«/usr/bin/python», «-c», «‘print \»Hello World!\»‘»]

• Run containers: To run a Docker container, you typically use the command docker pull to download the image containing the application you want to run inside the container. To start the container, use the command docker start. When the container is active, you can interact with the application inside the container using commands such as docker exec or docker run.

• generates an image of the container based on: Docker also provides some basic monitoring functionalities such as docker stats. To monitor containers in production, organizations use monitoring solutions such as Datadog, Splunk and Amazon Web Services

Benefits of containers.

• Learning new technologies: to learn a new tool without wasting time on installation and configuration. Docker Hub it's a repository where you can find containers with pre-installed and configured applications. For example, if you want an environment to learn how Redis works, simply run “docker run -it -p 6379:6379 redis bash”

• Reproducibility: Similar to a Java application, which will function exactly the same on any device capable of running a Java Virtual Machine, a Docker container is guaranteed to be identical on any computer or VPS that can run Docker. The exact specifications of a container are stored in a file. Dockerfile. By distributing this file, an organization can ensure that all images created from it are protected. Dockerfile function identically. Furthermore, having a consistent and well-documented environment makes it easier to monitor your application and identify problems.

• Isolation: Dependencies or configurations within a container will not affect any installations or configurations on the server, or in any other running container. By using separate containers for each application component (for example, a web server, a front-end interface, and a database to host a website), you can avoid conflicting dependencies. You can also run multiple projects on a single server without worrying about creating conflicts on your system.

• Security: separating the different components of a large application into different containers can have security benefits: if one container is compromised, the others will not be affected.

• Environmental management: Docker makes it easy to maintain different versions of a website that uses Nginx. You can have separate containers for testing, development, and production on the same server and easily start each one.

• Continuous integration: Docker works well as a continuous integration system with tools like Jenkins.

• Cost reduction: Docker requires fewer hours of implementation and environment adaptation, and fewer resources, than a Virtual Machine.

Conclusion

Although Docker has become a popular way to configure, store, and share resources, it shouldn't be used indiscriminately. At Soltel, thanks to our team of cutting-edge technology experts, we can advise our clients on making the right decisions for their projects.