The idea of flakes is how you define inputs, and you define the system (and packages, and shell etc.) in the outputs using the inputs. The inputs are git repos which point to other flakes. You can mix and match these as much as you want (see the devos repo for examples) and when you build the derivation, it generates a lockfile for exact commits in that point in time what were used in the given inputs.
You commit the lockfile and in the other systems where you pull your config from the repo, it uses exactly those commits and installs the same versions as you did in your other systems.
This was quite annoying and hard to do before flakes. Now it's easy.
The problem what people face with building their system as a flake is combining the packages so you can point to `jq` from the unstable nixos and firefox from the stable train. I think this aspect needs better documentation so it wouldn't be so damn hard to learn (believe me, I know). Luckily there are projects like devos that give a nice template for people to play with (with documentation!)
Another use for flakes is to create a development shell for your repo, an example what I did a while ago:
Either have `nix-direnv` installed, enter the directory and say `direnv allow`, or just `nix develop` and it will gather, compile and install the correct versions of packages to your shell. Updating the packages? Call `nix flake update` in the directory, commit the lockfile and everybody else gets the new versions to their shell.
https://github.com/divnix/devos
The idea of flakes is how you define inputs, and you define the system (and packages, and shell etc.) in the outputs using the inputs. The inputs are git repos which point to other flakes. You can mix and match these as much as you want (see the devos repo for examples) and when you build the derivation, it generates a lockfile for exact commits in that point in time what were used in the given inputs.
You commit the lockfile and in the other systems where you pull your config from the repo, it uses exactly those commits and installs the same versions as you did in your other systems.
This was quite annoying and hard to do before flakes. Now it's easy.
The problem what people face with building their system as a flake is combining the packages so you can point to `jq` from the unstable nixos and firefox from the stable train. I think this aspect needs better documentation so it wouldn't be so damn hard to learn (believe me, I know). Luckily there are projects like devos that give a nice template for people to play with (with documentation!)
Another use for flakes is to create a development shell for your repo, an example what I did a while ago:
https://github.com/pimeys/nix-prisma-example
Either have `nix-direnv` installed, enter the directory and say `direnv allow`, or just `nix develop` and it will gather, compile and install the correct versions of packages to your shell. Updating the packages? Call `nix flake update` in the directory, commit the lockfile and everybody else gets the new versions to their shell.