What is Docker, and Why You Should Be Using It?

2023-07-24 | By Maker.io Staff

This article serves as a high-level overview of Docker, an environment for managing application ‎containers. Read on to learn more about containers and how they can help both developers and ‎users cut down on the complexity that comes with testing and deploying software products.

What is Docker?

In essence, Docker is an open-source platform for managing extremely lightweight virtual ‎environments. These environments, called containers, can run many different applications, such ‎as those necessary for developing and testing programs, and can house applications and ‎services such as mock endpoints, web servers, database systems, and even custom ‎applications. Containers are isolated from one another, meaning they can’t influence each other. ‎This, in turn, makes them more secure, as a fault in one container will only affect that single ‎container without crashing the others. However, when the containers expose their ports, services ‎can still communicate via interfaces, such as standard TCP/IP sockets. Docker also acts as a ‎separating layer between applications and the operating system, which allows porting containers ‎from one system to another with minimal effort.

Who can Benefit from Using Docker?

Using containers benefits both developers and users in multiple ways. First, you can install ‎packaged software or a set of services from other sources conveniently. As each pre-built ‎container includes all application settings, they are easy to install, deploy, start, reset, and delete. ‎You can also effortlessly move containers around from one compatible system to another, which ‎makes sharing custom applications more convenient. In this context, Docker helps manage ‎dependencies that you would otherwise have to install and manage yourself.

What is Docker, and Why You Should Be Using It? Think of containers as self-contained units that help deploy, scale, secure, and maintain ‎software products. They can also be useful in development, as containers can increase ‎reproducibility in software testing, for example. Image Source: https://pixabay.com/photos/dock-container-export-cargo-441989/

Since these containers can easily be created and thrown away, you can set up standardized ‎testing environments that allow you to build deterministic unit tests more easily. For example, ‎you can initialize a new container with a test database at the start of the test run. The test cases ‎may then alter the database as needed. Once the testing is done, Docker can delete the ‎container. Whenever you re-run the tests, the container is reverted to its initial state, ‎guaranteeing that data alterations won’t lead to unintended test failures.

The containers help use the available infrastructure more efficiently while also offering greater ‎separation and security than running programs in parallel, as containerized processes are ‎segregated and run independently. This separation into containers allows you to shut down single ‎processes. For example, if there is a fault or if you need to perform maintenance or updates, you ‎can shut down a single process without having to take down the entire application.

Limitations of Using Docker

As mentioned, you can imagine Docker containers as lightweight virtual machines. Yet this can ‎also be a limitation since Docker containers don’t offer the same level of segregation that ‎separate physical systems or even virtual machines could deliver. Docker also provides no ‎redundancy — if the computer that runs Docker crashes or Docker itself hangs, then all ‎containers may go offline. Therefore, users and developers must implement redundancy ‎measures outside of Docker if their application demands it.

What is Docker, and Why You Should Be Using It? Developers can use Docker through a command-line interface or using a GUI, as shown in this ‎image.

Lastly, Docker doesn’t offer the exact same functionality one would get when using standard ‎Unix containers, and some limitations apply. Two such examples involve using cron jobs and ‎syslog within containers. While Docker is great for managing single containers, orchestrating a ‎large number of individual containers that all use the physical hardware’s limited resources ‎requires other solutions, such as Kubernetes.

Summary

Docker is an environment for installing, managing, and running Unix containers more ‎conveniently, and benefits users and developers in multiple ways. First, Docker makes deploying, ‎installing, and removing applications and services more efficient and accessible. Containers can ‎help write deterministic unit tests, as you can quickly start them when running a test suite and ‎throw them away once testing is done. Finally, Docker helps segregate processes, potentially ‎increasing security, and maintainability.

However, Docker imposes a few limitations due to its ease of use and lightweight nature. While ‎Docker offers some level of separation, its containers are not as segregated as on a virtual ‎machine, and you will still have to take care of redundancy if reliability is a concern. Remember ‎that Docker doesn’t offer the same functionality as standard Unix containers, and some ‎limitations apply.