I looked at testcontainers and ended up rolling my own version. One issue I had is that Docker is a very leaky abstraction. I needed to write one test and have it run in all these scenarios:

- on a Mac

- on a Linux VM

- in a Docker container on a Linux VM, with a Docker socket mounted

The networking for each of these is completely different. I had to make some opinionated choices to get code that could run in all cases. And running inside Docker prevented the test from being able to mount arbitrary files into the test containers, which turns out to be a requirement often. I ended up writing code to build a new image for each container, using ADD to inject files.

I also wanted all the tests to run in parallel and spit out readable logs from every container (properly associated with the correct test).

Not sure if any of these things have changed in testcontainers since I last looked, but these are the things I ran into. It took maybe a month of off and on tweaking, contrary to some people here claiming it can be done in an hour. As always, the devil is in the details.

edit: I did end up stealing ryuk. That thing can’t really be improved upon.