> Although on systems like Fly where you attempt to build one container to run an app, it’s a bit overkill.
I never used Fly but hosting a web + worker combo is common in a lot of tech stacks and with Docker it's really common to use 1 image to drive both containers with a different command. If Fly doesn't support that then I'd suggest hosting things elsewhere. Docker Compose and Kubernetes supports this no problem, it's a really basic / day 1 use case.