I used to install everything on my machine. I used to have ruby, nodejs, python, java, rebol, red and all the programming languages and environments, their packagers and tools I needed installed on my machine. It was heaven. Except for the moment when I had to install a new tool, that needed a newer version, and the old ones might broke and then I had to choose or reinstall every time, switch to rvm, nvm, pyenv or something else. For a while vagrant was cool.

Finally, I settled with docker.

The itch

I am working with nodejs for some years now. I worked in projects with many packages which we maintained. We had linked the packages and worked on many of them in parallel. Eventually the globally installed nodejs, even via nvm became a hazzle and caused bugs and glitches that consumed so much time, that I needed to scratch this itch. But that was not enough yet, I didn't fix it then. I also didn't know how.

Another eye opener for me was when I came back to a project years later which had no reproducable environment set up anywhere, that can run the project. I didn't even know which node version it had used, which npm version and how to run the project (docs were missing too, right). Even worse and more impactful, working in a team or company that has many projects and environments running. Each project needs to be installed on my machine. The worst and most time consuming I had until now was setting up a ruby environment just for running some CSS pre-processor, back in the days. I think I spent two days to get all the versions right and the CSS pre-processor to run.

Docker to the Rescue

The reproducability and the isolation of the environments are the main reasons why I started using docker, after a short detour to nixpkgs, where the UX made me fail.

With docker I need two dependencies, the docker runtime and docker-compose and I can install any package or setup, even a complex setup, in a way that even any colleague can get it up and running in minutes. The most important part is that it will create the same environment and no hidden, lingering side-effects caused by a tiny difference or alike that will cost a lot more time some time later. Ok, there are flaws to docker, there are side-effects and issues, but way less compared to not using it.

See my repo site-stitcher for an example of how I am using it for generating this website and read in docker vs. docker-compose about which I chose.

More

If you like to go deeper and ensure that even this setup is tested and wont break when you update your Dockerfile I even gave a talk on how to TDD your next docker container.