Of course you can. That approach makes different tradeoffs, of course, but it's entirely possible. I have a "legacy" server with ~20 small/medium, non-containe

Of course you can. That approach makes different tradeoffs, of course, but it's entirely possible. I have a "legacy" server with ~20 small/medium, non-containerized applications running on it (Django, older Python frameworks, some Lisp & Scheme stuff, etc.), all running as system services and sitting behind an Nginx front-end. But I can see the merits of containers, and might containerize these apps & services some day.