servo: try to integrate peerswap with clightning, but it fails

hosts/by-name/servo/services/cryptocurrencies/clightning.nix

@@ -70,7 +70,7 @@
 #   - maxfeepercent defaults to 0.5
 #   - label is a human-friendly label for my records
 
-{ config, ... }:
+{ config, pkgs, ... }:
 {
   sane.persist.sys.byStore.ext = [
     { user = "clightning"; group = "clightning"; mode = "0710"; path = "/var/lib/clightning"; }
@@ -117,6 +117,12 @@
   # - feature configs (i.e. experimental-xyz options)
   sane.services.clightning.extraConfig = ''
     log-level=debug:lightningd
+    # peerswap:
+    # - config example: <https://github.com/fort-nix/nix-bitcoin/pull/462/files#diff-b357d832705b8ce8df1f41934d613f79adb77c4cd5cd9e9eb12a163fca3e16c6>
+    # XXX: peerswap crashes clightning on launch. stacktrace is useless.
+    # plugin=${pkgs.peerswap}/bin/peerswap
+    # peerswap-db-path=/var/lib/clightning/peerswap/swaps
+    # peerswap-policy-path=...
   '';
   sane.services.clightning.extraConfigFiles = [ config.sops.secrets."lightning-config".path ];
   sops.secrets."lightning-config" = {

pkgs/additional/peerswap/default.nix

@@ -26,6 +26,24 @@ buildGoModule rec {
   vendorHash = "sha256-OOwXWsFVxieOtzF7arXVNeWo4YB/EQbxQMAIxDVIhfg=";
   proxyVendor = true;
 
+  postPatch = ''
+    # upstream Makefile builds with `-ldflags "-X main.GitCommit=<hash>"`, but we bypass Makefile and have to do that manually.
+    # GOFLAGS or CGO_LDFLAGS could both sort of do this, but they struggle with the spaces/quoting of the above,
+    # so instead i manually patch in the values
+    substituteInPlace cmd/peerswap-plugin/main.go \
+      --replace 'var GitCommit string' 'var GitCommit string = "${src.rev}"'
+    substituteInPlace cmd/peerswaplnd/peerswapd/main.go \
+      --replace 'var GitCommit string' 'var GitCommit string = "${src.rev}"'
+    substituteInPlace cmd/peerswaplnd/pscli/main.go \
+      --replace 'var GitCommit string' 'var GitCommit string = "${src.rev}"'
+  '';
+
+  postInstall = ''
+    # the upstream Makefile compiles peerswap-plugin/main.go into a binary named `peerswap`,
+    # but since we use buildGoModule, that doesn't go through the Makefile and we have to manually rename.
+    mv $out/bin/peerswap-plugin $out/bin/peerswap
+  '';
+
   meta = with lib; {
     description = "PeerSwap enables Lightning Network nodes to balance their channels by facilitating atomic swaps with direct peers.";
     homepage = "https://peerswap.dev";