For my side projects I just wrote a simple service that listens for Github events and just checks out the repo, builds it, and ssh's to the target server and runs a "stop and run" script. This way I can even put all of the configuration for the different databases in version control too.

It's super dirty, but I can deploy dozens of services without issue. Monitoring is another problem, but I don't need Prometheus for this stuff.

(I couldn't use Heroku cost effectively because running graph dbs and some custom stuff, but Heroku is AWESOME)