How to handle dependencies between units?

[andymass]

Currently all units are spawned in parallel at the same time. Sometimes, we might require a unit to be started before another. Can there be a way to specify Before= After=? Open question: how does a unit signal it has "started?"

[drubinstein]

It's an interesting idea. What use cases do you have in mind for dependencies between units? docker-compose used to have a depends_on key, but eventually removed it. With a good enough use case (keeping in mind that python-compose is meant for services and not as a generic workflow engine), I see no issue with implementing something similar for python-compose.

As a hack, there's nothing stopping you from adding a heartbeat endpoint to your Python services and waiting for those to respond 200 in the services that depend on the services with the heartbeat.