Hey everyone. Flake novice here. I used a flake to create a reproducible development shell for one of my python applications. So far, so good.

Then I wanted to integrate my application into my configuration.nix and run it as a recurring service via systemd. To this end, (after browsing github for inspiration), in my nix config repo I created a pkgs/app/default.nix, which points to the github repo of my application, and a modules/app/default.nix, which defines settings and applies those appropriately. My configuration.nix imports the app's module and enables it. Although it took me a while cause I'm new to Nix, I got that setup working after a while.

Now I'd like to turn the second part (module, pkg definitions) into a flake, and have some questions about that. Because there's so many open questions, I'll just post them in the order that makes sense to me. Any help/pointers would be greatly appreciated:

• When searching for flakes on github, I only found repos that turn other repos into flakes. Is there a reason to separate the flake part from the code part? Or is this mainly due to people turning other people's applications into flakes?
• What if I want to turn code I maintain into a flake? Should I also use dedicated repos for the application and the flake? Since I already have a flake.nix file for the development shell in my application's repo, at first glance it doesn't make sense to me to have a dedicated repo for the module/pkg functionality because there's a chance the lock files are not in sync so you might be running different code/deps than you're using during development.
• If it's therefore considered a best practice to put the functionality for the devshell and packaging into the same repo, is there some other set of best practices about the layout? On one hand, I don't want to stuff the code repo with nix-specific directories and files; on the other, putting everything into flake.nix might make the code cluttered.
• Last but not least, how do I port the functionality from the {pkgs,module}/app/default.nix files so it can be used as a flake in my configuration.nix? If anyone has a (preferably simple) example repo on github, that would be great.
  Sorry for the lengthy list, but I felt putting all questions out there so people can immediately shoot down stupid questions and point me into the right direction. Thanks!

I finally got around to adding the nixosModules target to my flake. Now I wonder how to correctly enable the service defined in the module in my configuration.nix. Before, I did import modules/app and services.app.enable = true;.

To use the flake for my app, I added it as input to the flake for my host configuration, and passed it as input to my configuration.nix. That got me the error error: The option services.p2p-crawler' does not exist.. After going through some examples, I tried adding my_app.nixosModules.my_appto the modules in my nixosConfigurations (similar to what I have for home manager), but that landed me aerror: attribute 'p2p-crawler' missing`. Did I do something wrong in my app's flake, or am I using the flake wrong?

I finally got around to adding the nixosModules target to my flake. Now I wonder how to correctly enable the service defined in the module in my configuration.nix. Before, I did import modules/app and services.app.enable = true;.

To use the flake for my app, I added it as input to the flake for my host configuration, and passed it as input to my configuration.nix. That got me the error error: The option services.p2p-crawler' does not exist.. After going through some examples, I tried adding my-app.nixosModules.my-appto the modules in mynixosConfigurations (similar to what I have for home manager), but that landed me aerror: attribute 'p2p-crawler' missing`. Did I do something wrong in my app's flake, or am I using the flake wrong?

I finally got around to adding the nixosModules target to my flake. Now I wonder how to correctly enable the service defined in the module in my configuration.nix. Before, I did import modules/app and services.app.enable = true;.

To use the flake for my app, I added it as input to the flake for my host configuration, and passed it as input to my configuration.nix. That got me the error error: The option services.p2p-crawler' does not exist.. After going through some examples, I tried adding my-app.nixosModules.my-app to the modules in mynixosConfigurations (similar to what I have for home manager), but that landed me aerror: attribute 'p2p-crawler' missing`. Did I do something wrong in my app's flake, or am I using the flake wrong?

I finally got around to adding the nixosModules target to my flake. Now I wonder how to correctly enable the service defined in the module in my configuration.nix. Before, I did import modules/app and services.app.enable = true;.

To use the flake for my app, I added it as input to the flake for my host configuration, and passed it as input to my configuration.nix. That got me the error error: The option services.p2p-crawler' does not exist.. After going through some examples, I tried adding my-app.nixosModules.my-app to the modules in mynixosConfigurations (similar to what I have for home manager), but that landed me aerror: attribute 'p2p-crawler' missing\. Did I do something wrong in my app's flake, or am I using the flake wrong?