Understanding the depends_on condition in Docker compose files
It's only been ten days or so since I learned the trick, even though it was well documented: managing service startups and, above all, blocking one if the other isn't ready (official documentation).
Imagine a two services applications like Joomla (see my Create your Joomla website using Docker), WordPress, LimeSurvey, Laravel and many, many more use cases: you've an application and that application requires a database.