Make it simpler to extend nix-bitcoin

[jonasnick]

There are many more packages and modules I would like to experiment with on my nix-bitcoin node. It seems like there's at least half a dozen usable frontends for lnd. However, maintaining all of this in this repo does not really scale. That's evident from the time it takes for some PRs to get reviews. Ideally, nix-bitcoin would be very minimal - perhaps only bitcoind, clightning and lnd as well as the secrets, netns, test, etc infrastructure) - and allow external repos to use these capabilities and add their own packages/modules.

As far as I understand, the (currently experimental) flakes features was invented in part because the nixpkgs repo does not scale and it's planned to split it up. Similarly, if we want to go forward with this issue we should look into how flakes as a standard way to compose nix expressions can help with that.

[nixbitcoin]

Concept ACK

[jonasnick]

When looking at the btcpayserver module we can see that the main modules that need additional changes in order to add a module are

• backup
• nodeinfo
• netns

We should refactor these modules to provide options that achieve the same without having to touch the module. For example, in case of the backup module we want an option that allows adding directories to back up.

[nixbitcoin]

Should this be included in https://github.com/fort-nix/nix-bitcoin/milestone/2?

[jonasnick]

Do you mean refactoring the modules? I don't think so, because it's not user visible.

[nixbitcoin]

Has this been taken care of through @erikarvstedt's various refactorings?