Lightning loop

.travis.yml

@@ -28,6 +28,7 @@ env:
   - PKG=electrs STABLE=1
   - PKG=electrs STABLE=0
   - PKG=liquid-swap STABLE=1
+  - PKG=lightning-loop STABLE=0
   - PKG=nixops19_09 STABLE=1
 script:
   - printf '%s (%s)\n' "$NIX_PATH" "$VER"

examples/configuration.nix

@@ -129,6 +129,12 @@
   # a network-level as much as possible.
   # nix-bitcoin.netns-isolation.enable = true;
 
+  ### lightning-loop
+  # Enable this module to use lightninglab's non-custodial off/on chain bridge.
+  # loopd (lightning-loop daemon) will be started automatically. Users can
+  # interact with off/on chain bridge using `loop in` and `loop out`.
+  # services.lightning-loop.enable = true;
+
   # FIXME: Define your hostname.
   networking.hostName = "nix-bitcoin";
   time.timeZone = "UTC";

modules/lightning-loop.nix

@@ -0,0 +1,72 @@
+{ config, lib, pkgs, ... }:
+
+with lib;
+
+let
+  cfg = config.services.lightning-loop;
+  inherit (config) nix-bitcoin-services;
+  secretsDir = config.nix-bitcoin.secretsDir;
+in {
+
+  options.services.lightning-loop = {
+    enable = mkEnableOption "lightning-loop";
+    package = mkOption {
+      type = types.package;
+      default = pkgs.nix-bitcoin.lightning-loop;
+      defaultText = "pkgs.nix-bitcoin.lightning-loop";
+      description = "The package providing lightning-loop binaries.";
+    };
+    proxy = mkOption {
+      type = types.nullOr types.str;
+      default = null;
+      description = "Connect through SOCKS5 proxy";
+    };
+    extraArgs = mkOption {
+      type = types.separatedString " ";
+      default = "";
+      description = "Extra command line arguments passed to loopd.";
+    };
+    cli = mkOption {
+      default = pkgs.writeScriptBin "loop"
+      # Switch user because lnd makes datadir contents readable by user only
+      ''
+        exec sudo -u lnd ${cfg.package}/bin/loop "$@"
+      '';
+      description = "Binary to connect with the lnd instance.";
+    };
+    enforceTor =  nix-bitcoin-services.enforceTor;
+  };
+
+  config = mkIf cfg.enable {
+    assertions = [
+      { assertion = config.services.lnd.enable;
+        message = "lightning-loop requires lnd.";
+      }
+    ];
+
+    environment.systemPackages = [ cfg.package (hiPrio cfg.cli) ];
+
+    systemd.services.lightning-loop = {
+      description = "Run loopd";
+      wantedBy = [ "multi-user.target" ];
+      requires = [ "lnd.service" ];
+      after = [ "lnd.service" ];
+      serviceConfig = nix-bitcoin-services.defaultHardening // {
+        ExecStart = ''
+          ${cfg.package}/bin/loopd \
+          --lnd.host=${config.services.lnd.listen}:10009 \
+          --lnd.macaroondir=${config.services.lnd.dataDir}/chain/bitcoin/mainnet \
+          --lnd.tlspath=${secretsDir}/lnd-cert \
+          ${optionalString (cfg.proxy != null) "--server.proxy=${cfg.proxy}"} \
+          ${cfg.extraArgs}
+        '';
+        User = "lnd";
+        Restart = "on-failure";
+        RestartSec = "10s";
+        ReadWritePaths = "${config.services.lnd.dataDir}";
+      } // (if cfg.enforceTor
+          then nix-bitcoin-services.allowTor
+          else nix-bitcoin-services.allowAnyIP);
+    };
+  };
+}

modules/lnd.nix

@@ -159,7 +159,7 @@ in {
         in [
           # Run fully privileged for secrets dir write access
           "+${nix-bitcoin-services.script ''
-            attempts=50
+            attempts=250
             while ! { exec 3>/dev/tcp/127.0.0.1/${restPort} && exec 3>&-; } &>/dev/null; do
                   ((attempts-- == 0)) && { echo "lnd REST service unreachable"; exit 1; }
                   sleep 0.1

modules/modules.nix

@@ -13,6 +13,7 @@
     ./recurring-donations.nix
     ./hardware-wallets.nix
     ./lnd.nix
+    ./lightning-loop.nix
     ./secrets/secrets.nix
     ./netns-isolation.nix
     ./dbus.nix

modules/netns-isolation.nix

@@ -127,6 +127,10 @@ in {
           id = 21;
           connections = [];
         };
+        lightning-loop = {
+          id = 22;
+          connections = [ "lnd" ];
+        };
       };
 
       systemd.services = {
@@ -291,6 +295,14 @@ in {
       # nginx: Custom netns configs
       services.nix-bitcoin-webindex.host = mkIf config.services.nix-bitcoin-webindex.enable netns.nginx.address;
 
+      # loop: Custom netns configs
+      services.lightning-loop = mkIf config.services.lightning-loop.enable {
+        cli = pkgs.writeScriptBin "loop"
+        # Switch user because lnd makes datadir contents readable by user only
+        ''
+          netns-exec nb-lightning-loop sudo -u lnd ${config.services.lightning-loop.package}/bin/loop "$@"
+        '';
+      };
     })
     # Custom netns config option values if netns-isolation not enabled
     (mkIf (!cfg.enable) {

modules/presets/secure-node.nix

@@ -91,6 +91,12 @@ in {
     };
     services.tor.hiddenServices.lnd = mkIf cfg.lnd.enable (mkHiddenService { port = cfg.lnd.onionport; toHost = cfg.lnd.listen; });
 
+    # lightning-loop
+    services.lightning-loop = {
+      proxy = cfg.tor.client.socksListenAddress;
+      enforceTor = true;
+    };
+
     # liquidd
     services.liquidd = {
       rpcuser = "liquidrpc";

pkgs/default.nix

@@ -11,6 +11,7 @@
   generate-secrets = pkgs.callPackage ./generate-secrets { };
   nixops19_09 = pkgs.callPackage ./nixops { };
   netns-exec = pkgs.callPackage ./netns-exec { };
+  lightning-loop = pkgs.callPackage ./lightning-loop { };
 
   pinned = import ./pinned.nix;
 }

pkgs/lightning-loop/default.nix

@@ -0,0 +1,23 @@
+{ pkgs, buildGoModule, fetchurl, lib }:
+
+buildGoModule rec {
+  pname = "lightning-loop";
+  version = "0.7.0-beta";
+
+  src = fetchurl {
+    url = "https://github.com/lightninglabs/loop/archive/v${version}.tar.gz";
+    # Use ./get-sha256.sh to fetch latest (verified) sha256
+    sha256 = "fbb5ae6dd55002a632a924e41a0bb2ce886eb9e834668be35b312b14e8b68233";
+  };
+
+  subPackages = [ "cmd/loop" "cmd/loopd" ];
+
+  vendorSha256 = "1g0l09zcic5nnrsdyap40dj3zl59gbb2k8iirhph3257ysa52mhr";
+
+  meta = with lib; {
+    description = " Lightning Loop: A Non-Custodial Off/On Chain Bridge";
+    homepage = "https://github.com/lightninglabs/loop";
+    license = lib.licenses.mit;
+    maintainers = with maintainers; [ nixbitcoin ];
+  };
+}

pkgs/lightning-loop/get-sha256.sh

@@ -0,0 +1,27 @@
+#! /usr/bin/env nix-shell
+#! nix-shell -i bash -p git gnupg
+set -euo pipefail
+
+TMPDIR="$(mktemp -d -p /tmp)"
+trap "rm -rf $TMPDIR" EXIT
+cd $TMPDIR
+
+echo "Fetching latest release"
+git clone https://github.com/lightninglabs/loop 2> /dev/null
+cd loop
+latest=$(git describe --tags `git rev-list --tags --max-count=1`)
+echo "Latest release is ${latest}"
+
+# GPG verification
+export GNUPGHOME=$TMPDIR
+echo "Fetching Joost Jager's Key"
+gpg --keyserver hkps://keyserver.ubuntu.com --recv-keys D146D0F68939436268FA9A130E26BB61B76C4D3A 2> /dev/null
+echo "Fetching Alex Bosworth's Key"
+gpg --keyserver hkps://keyserver.ubuntu.com --recv-keys DE23E73BFA8A0AD5587D2FCDE80D2F3F311FD87E 2> /dev/null
+
+echo "Verifying latest release"
+git verify-tag ${latest}
+
+echo "tag: ${latest}"
+# The prefix option is necessary because GitHub prefixes the archive contents in this format
+echo "sha256: $(git archive --format tar.gz --prefix=loop-${latest//v}/ ${latest} | sha256sum | cut -d\  -f1)"

pkgs/netns-exec/src/main.c

@@ -14,6 +14,7 @@
 
 static char *available_netns[] = {
     "nb-lnd",
+    "nb-lightning-loop",
     "nb-bitcoind",
     "nb-liquidd"
 };

pkgs/pinned.nix

@@ -11,7 +11,9 @@ in
     bitcoind
     clightning
     lnd;
-  inherit (nixBitcoinPkgsUnstable) electrs;
+  inherit (nixBitcoinPkgsUnstable)
+    electrs
+    lightning-loop;
 
   stable = nixBitcoinPkgsStable;
   unstable = nixBitcoinPkgsUnstable;

test/scenarios/default.py

@@ -79,3 +79,13 @@
 succeed("systemctl start lnd")
 assert_matches("su operator -c 'lncli getinfo' | jq", '"version"')
 assert_no_failure("lnd")
+
+### Test loopd
+
+succeed("systemctl start lightning-loop")
+assert_matches("su operator -c 'loop --version'", "version")
+# Check that lightning-loop fails with the right error, making sure
+# lightning-loop can connect to lnd
+machine.wait_until_succeeds(
+    log_has_string("lightning-loop", "chain notifier RPC isstill in the process of starting")
+)

test/scenarios/withnetns.py

@@ -141,3 +141,13 @@
 succeed("systemctl start lnd")
 assert_matches("su operator -c 'lncli getinfo' | jq", '"version"')
 assert_no_failure("lnd")
+
+### Test loopd
+
+succeed("systemctl start lightning-loop")
+assert_matches("su operator -c 'loop --version'", "version")
+# Check that lightning-loop fails with the right error, making sure
+# lightning-loop can connect to lnd
+machine.wait_until_succeeds(
+    log_has_string("lightning-loop", "chain notifier RPC isstill in the process of starting")
+)

test/test.nix

@@ -34,6 +34,8 @@ import ./make-test.nix rec {
 
     services.lnd.enable = true;
     systemd.services.lnd.wantedBy = mkForce [];
+    services.lightning-loop.enable = true;
+    systemd.services.lightning-loop.wantedBy = mkForce [];
 
     services.electrs.enable = true;