1 files changed, 72 insertions, 0 deletions
diff --git a/nixos/modules/services/networking/epmd.nix b/nixos/modules/services/networking/epmd.nix
new file mode 100644
index 00000000000..75d78476e57
--- /dev/null
+++ b/nixos/modules/services/networking/epmd.nix
@@ -0,0 +1,72 @@
+{ config, lib, pkgs, ... }:
+
+with lib;
+
+let
+  cfg = config.services.epmd;
+in
+{
+  ###### interface
+  options.services.epmd = {
+    enable = mkOption {
+      type = types.bool;
+      default = false;
+      description = ''
+        Whether to enable socket activation for Erlang Port Mapper Daemon (epmd),
+        which acts as a name server on all hosts involved in distributed
+        Erlang computations.
+      '';
+    };
+    package = mkOption {
+      type = types.package;
+      default = pkgs.erlang;
+      defaultText = literalExpression "pkgs.erlang";
+      description = ''
+        The Erlang package to use to get epmd binary. That way you can re-use
+        an Erlang runtime that is already installed for other purposes.
+      '';
+    };
+    listenStream = mkOption
+      {
+        type = types.str;
+        default = "[::]:4369";
+        description = ''
+          the listenStream used by the systemd socket.
+          see https://www.freedesktop.org/software/systemd/man/systemd.socket.html#ListenStream= for more informations.
+          use this to change the port epmd will run on.
+          if not defined, epmd will use "[::]:4369"
+        '';
+      };
+  };
+
+  ###### implementation
+  config = mkIf cfg.enable {
+    assertions = [{
+      assertion = cfg.listenStream == "[::]:4369" -> config.networking.enableIPv6;
+      message = "epmd listens by default on ipv6, enable ipv6 or change config.services.epmd.listenStream";
+    }];
+    systemd.sockets.epmd = rec {
+      description = "Erlang Port Mapper Daemon Activation Socket";
+      wantedBy = [ "sockets.target" ];
+      before = wantedBy;
+      socketConfig = {
+        ListenStream = cfg.listenStream;
+        Accept = "false";
+      };
+    };
+
+    systemd.services.epmd = {
+      description = "Erlang Port Mapper Daemon";
+      after = [ "network.target" ];
+      requires = [ "epmd.socket" ];
+
+      serviceConfig = {
+        DynamicUser = true;
+        ExecStart = "${cfg.package}/bin/epmd -systemd";
+        Type = "notify";
+      };
+    };
+  };
+
+  meta.maintainers = teams.beam.members;
+}