We used them in a web agency that has lots of different projects running on different stacks, and we have to go back to old projects from time to time. Having y

We used them in a web agency that has lots of different projects running on different stacks, and we have to go back to old projects from time to time. Having your dependencies, version, setup and even build tools all referenced in a compose file made it really easy and quick to switch projects or get a new developer set up. Simply git clone, docker-compose up and voilà. No more messing around with installing different and conflicting dependencies on the same machine, and much faster, easier and more stable than the vagrant/ansible-combo we used before that.