Add recurring donations module

README.md

@@ -39,6 +39,7 @@ In `configuration.nix` the user can enable:
 * an index page using nginx to display node information and link to nanopos
 * [spark-wallet](https://github.com/shesek/spark-wallet)
 * [electrs](https://github.com/romanz/electrs)
+* recurring-donations, a module to repeatedly send lightning payments to recipients specified in the configuration.
 
 The data directories of the services can be found in `/var/lib` on the deployed machines.
 

configuration.nix

@@ -58,6 +58,17 @@
   # this if clightning, lightning-charge, and nanopos are enabled.
   # services.nix-bitcoin-webindex.enable = true;
 
+  ### RECURRING-DONATIONS
+  # Enable this module to send recurring donations. Only enable this if
+  # clightning is enabled.
+  # services.recurring-donations.enable = true;
+  # Specify the receivers of the donations. By default donations are every
+  # Monday at a randomized time.
+  # services.recurring-donations.tallycoin = {
+  #   "djbooth007" = 1000;
+  #   "hillebrandmax" = 1000;
+  # };
+
   # FIXME: Define your hostname.
   networking.hostName = "nix-bitcoin";
   time.timeZone = "UTC";

modules/default.nix

@@ -10,4 +10,5 @@
   nix-bitcoin-pkgs = ./nix-bitcoin-pkgs.nix;
   nix-bitcoin-webindex = ./nix-bitcoin-webindex.nix;
   spark-wallet = ./spark-wallet.nix;
+  recurring-donations = ./recurring-donations.nix
 }

modules/nix-bitcoin.nix

@@ -26,6 +26,7 @@ in {
     ./spark-wallet.nix
     ./electrs.nix
     ./onion-chef.nix
+    ./recurring-donations.nix
   ];
 
   options.services.nix-bitcoin = {

modules/recurring-donations.nix

@@ -0,0 +1,108 @@
+{ config, lib, pkgs, ... }:
+
+with lib;
+
+let
+  cfg = config.services.recurring-donations;
+  recurring-donations-script = pkgs.writeScript "recurring-donations.sh" ''
+    LNCLI="lightning-cli --lightning-dir=${config.services.clightning.dataDir}"
+    pay_tallycoin() {
+      NAME=$1
+      AMOUNT=$2
+      echo Attempting to pay $AMOUNT sat to $NAME
+      INVOICE=$(torsocks curl -d "satoshi_amount=$AMOUNT&payment_method=ln&id=$NAME&type=profile" -X POST https://api.tallyco.in/v1/payment/request/ | jq -r '.lightning_pay_request') 2> /dev/null
+      if [ -z "$INVOICE" ] || [ "$INVOICE" = "null" ]; then
+        echo "ERROR: did not get invoice from tallycoin"
+        return
+      fi
+      # Decode invoice and compare amount with requested amount
+      DECODED_AMOUNT=$($LNCLI decodepay "$INVOICE" | jq -r '.amount_msat' | head -c 4)
+      if [ -z "$DECODED_AMOUNT" ] || [ "$DECODED_AMOUNT" = "null" ]; then
+        echo "ERROR: did not get response from clightning"
+        return
+      fi
+      if [ $DECODED_AMOUNT -eq $AMOUNT ]; then
+        echo Paying with invoice "$INVOICE"
+        $LNCLI pay "$INVOICE"
+      else
+        echo ERROR: requested amount and invoice amount do not match. $AMOUNT vs $DECODED_AMOUNT
+        return
+      fi
+    }
+    ${ builtins.foldl'
+      (x: receiver: x +
+        ''
+        pay_tallycoin ${receiver} ${toString (builtins.getAttr receiver cfg.tallycoin)}
+        '')
+      ""
+      (builtins.attrNames cfg.tallycoin)
+    }
+  '';
+in {
+  options.services.recurring-donations = {
+    enable = mkOption {
+      type = types.bool;
+      default = false;
+      description = ''
+        If enabled, the recurring-donations service will be installed.
+      '';
+    };
+    tallycoin = mkOption {
+      type = types.attrs;
+      default = {};
+      description = ''
+        This option is used to specify tallycoin donation receivers using an
+        attribute set.  For example the following setting instructs the module
+        to repeatedly send 1000 satoshis to djbooth007.
+        {
+          "djbooth007" = 1000;
+        }
+      '';
+    };
+    interval = mkOption {
+      type = types.string;
+      default = "Mon *-*-* 00:00:00";
+      description = ''
+        Schedules the donations. Default is weekly on Mon 00:00:00. See `man
+        systemd.time` for further options.
+      '';
+    };
+    randomizedDelaySec = mkOption {
+      type = types.int;
+      default = 86400;
+      description = ''
+        Random delay to add to scheduled time for donation. Default is one day.
+      '';
+    };
+  };
+
+  config = mkIf cfg.enable {
+    systemd.services.recurring-donations = {
+      description = "Run recurring-donations";
+      requires = [ "clightning.service" ];
+      after = [ "clightning.service" ];
+      path  = [ pkgs.clightning pkgs.curl pkgs.torsocks pkgs.sudo pkgs.jq ];
+      serviceConfig = {
+        ExecStart = "${pkgs.bash}/bin/bash ${recurring-donations-script}";
+        # TODO: would be better if this was operator, but I don't get sudo
+        # working inside the shell script
+        User = "clightning";
+        Type = "oneshot";
+        PrivateTmp = "true";
+        ProtectSystem = "full";
+        NoNewPrivileges = "true";
+        PrivateDevices = "true";
+      };
+    };
+    systemd.timers.recurring-donations = {
+      requires = [ "clightning.service" ];
+      after = [ "clightning.service" ];
+      timerConfig = {
+        Unit = "recurring-donations.service";
+        OnCalendar = cfg.interval;
+        RandomizedDelaySec = toString cfg.randomizedDelaySec;
+      };
+      wantedBy = [ "multi-user.target" ];
+    };
+  };
+}