Problem with config files is you are forced to process it properly in pipeline so it can be delivered during deploy AND depending on your runtime environment, you might have to redeploy to change things.
Environment variables exist on just about EVERY runtime, changed without requiring a pipeline run.
However, subprocess is interesting but I've never run into subprocess that is not sharing a config. Where I worked, if you have subprocess that can't see those configs, you create a new service.
I'm not sure what you're saying about pipelines. Ultimately, every app process is started by some manager. It's just as easy for that manager to create a config file as it is to set environment variables.
If your point is that existing managers support setting environment variables but not creating config files, then sure. But that isn't a fundamental truth, it's just working with the tools you have.
Say you have a GitHub Action that pushes a container with your app and deploys to a Kubernetes cluster. Where is your config file going in this step? How do you inject that YAML/HCL/JSON file into the app to configure your app?
It just seems far easier to have your kube config inject the env variables from your kube file and that way you don't have to worry during deployment how to add that file and you don't check it into the source. This applies to basically any way you deploy your app, especially containerised ones. Unless you're running your app in an EC2 machine where you can go in and easily edit the file (not that you can't do it in a container), it just seems like extra steps. I've found the happy medium to be sourcing default configs from a file that can all be overridden through env variables
Makes sense. But this is exactly what i was saying: the tooling you're using makes it easy to set environment variables, and doesn't make it easy to add config files, so in this case, environment variables are easier to use than config files.
But there's no fundamental reason for that to be the case. You could imagine a very nearby parallel universe where Kubernetes config files don't let you set environment variables, but do let you inject files. In this universe, you can see other deployment approaches that make config files easier (Puppet and suchlike). And if you're building something from scratch, you can make the choice.
Well... yeah but in the universe we live in, env variables are the most convenient, interoperable way of configuring apps and work on almost every platform. I guess I could work on a way to sit and dump config files into my apps but what's the point when env vars work well and are convenient to use right now?
Environment variables exist on just about EVERY runtime, changed without requiring a pipeline run.
However, subprocess is interesting but I've never run into subprocess that is not sharing a config. Where I worked, if you have subprocess that can't see those configs, you create a new service.