Beginner’s Guide to Docker (Part 1): What’s Docker?

What is Docker?

Docker is one of those hot technologies on the market that every employer seems to want their candidates to have. For good reason — since Docker’s launch in 2013, Docker has completely transformed and taken over the software development world by storm. So what is this handy technology that developers swear by and that tech companies evangelize?

Docker is a containerization platform that allows developers to focus on coding instead of OS level dependency or image level issues. Imagine that you are trying to develop a program that runs only on a specific version of Linux. For your development team to develop this application, everyone would have to have an environment that ran that version of Linux and maintained the same dependencies. If the development team did not have uniform settings across their environments, that could produce hard to create bugs and issues that are exclusive to specific environments.

Enter Docker. Docker containers are self contained packages that are isolated from each other that you can regularize installation for. Say that you want a version of Ubuntu installed from several years back — you can create a Docker with that version of Ubuntu and share that image with your application installed on it. Then, everyone who installs that image will have your exact same configuration, and developers can have a much easier time collaborating.

This paradigm shift has liberated a lot of developer hours from troubleshooting dependency issues or virtual machine issues. For that reason, Docker is a technology to watch and learn, as it will continue to provide that utility to technology and development companies around the world.

Get Started

To get started, visit the docker website and install the Docker version for your OS here:

Get Docker

Then, with it installed, you can test it in your command line using the following command:

docker --version

Then, you can run a Docker by simply using the docker run command with an existing image, such as the hello-world app:

docker run hello-world

This is one of the images I referred to earlier, which you can create with configurations to share. You can then confirm that the image in on your machine using the following command:

docker image ls

Conclusion

With these simple steps, you can see how powerful Docker can be! Someone else created a hello-world app, and you can pull it from Docker’s servers and have an image of their setup ready to go with a simple terminal command. Imagine how this would work with your own apps. You could create docker images for specific branches that updated the OS and then share that with other developers to make sure there were no bugs with the new OS. You could spin up a new image as a snapshot of development for a working environment before embarking on a feature that could break your environment. The sky’s the limit here, and this is just the start of our Docker journey. In future articles, we will actually build and run our docker images, and see how day to day usage of Docker works.

Sources

Orientation and setup