Agreed.
I've recently switched from docker compose to process compose and it's super nice not to have to map ports or mount volumes. What I actually needed from docker had to do less with containers and more with images, and nix solves that problem better without getting in the way at runtime.
Assuming I've found the right process-compose [1], it struck me as having much overlap with the features of systemd. Or at least, I would tend to reach for systemd if I wanted something to run arbitrary processes. Is there something additional/better that process-compose does for you?
[1]: https://github.com/F1bonacc1/process-compose
That's the one, although I tend to reference it through https://github.com/juspay/services-flake because that way I end up using the community-maintained configs for whatever well-known services I've enabled (I'll use postgres as an example below, but there are many: https://community.flake.parts/services-flake/services)
What process-compose gives me is a single parent with all of that project's processes as children, and a nice TUI/CLI for scrolling through them to see who is happy/unhappy and interrogating their logs, and when I shut it down all of that project's dependencies shut down. Pretty much the same flow as docker-compose.
It's all self-contained so I can run it on MacOS and it'll behave just the same as on Linux (I don't think systemd does this, could be wrong), and without requiring me to solve the docker/podman/rancher/orbstack problem (these are dependencies that are hard to bundle in nix, so while everything else comes for free, they come at the cost of complicating my readme with a bunch of requests that the user set things up beforehand).
As a bonus, since it's a single parent process, if I decide to invoke it through libfaketime, the time inherited by subprocess so it's consistently faked in the database and the services and in observability tools...
My feeling for systemd is that it's more for system-level stuff and less for project-level dependencies. Like, if I have separate projects which need different versions of postgres, systemd commands aren't going to give me a natural way to keep track of which project's postgres I'm talking about. process-compose, however, will show me logs for the correct postgres (or whatever service) in these cases:
This is especially helpful because AI agents tend to be scoped to working directory. So if I have one instance of claude code on each monitor and in each directory, which ever one tries to look at postgres logs will end up looking at the correct postgres's logs without having to even know that there are separate ones running.Basically, I'm alergic to configuring my system at all. All dependencies besides nix, my text editor, and my shell are project level dependencies. This makes it easy to hop between machines and not really care about how they're set up. Even on production systems, I'd rather just clone the repo `nix run` in that dir (it then launches process compose which makes everything just like it was in my dev environment). I am however not in charge of any production systems, so perhaps I'm a bit out of touch there.