Correct, Docker doesn't care what you run inside the container. You provide a command to run, and it runs it. That command may be your application server or a t

Correct, Docker doesn't care what you run inside the container. You provide a command to run, and it runs it. That command may be your application server or a traditional init process which in turn will fork multiple children. Docker does make it easier to follow an "application container" pattern, and that pattern avoids (with good reason) booting an entire traditional init system inside the container. But following that pattern is not mandatory. Not forcing too many patterns upon users all at once was part of the original Docker philosophy. Unfortunately that aspect was drowned in the cacophony as a few loud and passionate people interpreted Docker through the lens of their own favorite patterns. In retrospect I wish we had been more assertive in reminding everyone to respect the philosophy behind Docker: that you can share tools with people without forcing everyone to use them in the same way as you.