lndhub-go: integrate LndHub.go

[prusnak]

LndHub.go is an accounting wrapper for the Lightning Network. It provides separate accounts for end-users and LndHub compatible API while written in Go.

upstream: https://github.com/getAlby/lndhub.go

This is a draft PR to gather feedback, also any help about how to test this is welcome!

Fixes #517

[erikarvstedt]

Thanks, Pavol, lndhub seems low maintenance and a good fit for nix-bitcoin. If it supported clightning, I'd use it right away.

Why do you set FEE_RESERVE to true (default is false)?

[prusnak]

If it supported clightning, I'd use it right away.

CLN might be supported in the future, see getAlby/lndhub.go#123

Why do you set FEE_RESERVE to true (default is false)?

Fixed in 644b632

[erikarvstedt]

Initial fixups to make the service run.
The postgresql connection fails with:

Jul 21 13:12:16 nb-test lndhub.go[5251]: {"level":"fatal","time":"2022-07-21T13:12:16+02:00","message":"Error initializing db migrator: pgdriver: SASL: FATAL: password authentication failed for user \"lndhub-go\" (SQLSTATE=28P01)"}

The best way to fix this is to make lndhub-go allow connections via the postgresql socket.

[erikarvstedt]

I've removed all app-specific settings and replaced them with option settings.
They can now be defined like this:

services.lndhub-go = {
  settings = {
    FEE_RESERVE = true;
    MAX_SEND_AMOUNT = 1000000;
  };
};

If you think some of these settings deserve a dedicated NixOS option, we can add them back in (maybe via a freeform module).

[prusnak]

Merged your fixups into my branch, thanks! Added bfceb1e which fixes the database name issue.

[erikarvstedt]

Fixups.
The postgres connection fails with:

Jul 21 14:40:23 nb-test lndhub.go[575]: {"level":"fatal","time":"2022-07-21T14:40:23+02:00","message":"Error initializing db migrator: pgdriver: SASL: FATAL: password authentication failed for user \"lndhub-go\" (SQLSTATE=28P01)"}

We can add a password via the secrets mechanism, but I'd really prefer a socket connection. This should be simple to add to lndhub.

[prusnak]

This should be simple to add to lndhub.

Maybe it is enough to just change the connection string to postgres:///lndhubgo?host=/var/run/postgresql/ ?

[erikarvstedt]

Ah, great.
With DATABASE_URI = "postgres:///lndhubgo?host=/run/postgresql"; connecting still fails:

Jul 21 16:03:10 nb-test lndhub.go[632]: {"level":"fatal","time":"2022-07-21T16:03:10+02:00","message":"Error initializing db migrator: dial unix /run/postgresql: connect: permission denied"}

But manually connecting via sudo -u lndhub-go psql lndhubgo --host=/run/postgresql works fine. Seems like a lndhub-go bug.

[prusnak]

Maybe we need to specify also the user?

DATABASE_URI = "postgres:///lndhubgo?host=/run/postgresql&user=${cfg.user}";

[erikarvstedt]

No, this didn't help. Same with the equivalent postgres://lndhub-go@/lndhubgo?host=/run/postgresql

[prusnak]

I figured it out. First, this PR has to be merged: getAlby/lndhub.go#215 and then one can use the following connection string: unix://${cfg.user}@lndhubgo/run/postgresql/.s.PGSQL.5432?sslmode=disable

[prusnak]

When getAlby/lndhub.go#218 is merged, we can remove the xxd shenanigans

[jonasnick]

Thanks, Pavol, lndhub seems low maintenance and a good fit for nix-bitcoin. If it supported clightning, I'd use it right away.

Agreed!

[prusnak]

Rebased and squashed. Added fixup commits that need to wait until next release of LndHub.go is released, containing getAlby/lndhub.go#215 and getAlby/lndhub.go#218

[prusnak]

lndhub-go 0.10.0 which contains the required fixes in getAlby/lndhub.go#215 and getAlby/lndhub.go#218 has been released and merged to nixpkgs via NixOS/nixpkgs#185649

[prusnak]

Rebased after #537 has been merged. Removing draft status.

[erikarvstedt]

Fixups.

[prusnak]

Fixups.

Pulled into the PR

[erikarvstedt]

ACK cff12ba

[erikarvstedt]

Final fixup

[prusnak]

Final fixup

applied to a03a0b7

[erikarvstedt]

ACK 6a195f6

[prusnak]

Dropped 6a195f6 since NixOS/nixpkgs#204769 has been merged and no longer required.

Rebased ...