Merge pull request #99934 from mayflower/murmur-env

nixos/murmur: add option `environmentFile` for injecting secrets

nixos/modules/services/networking/murmur.nix

@@ -241,6 +241,34 @@ in
         default = "";
         description = "Extra configuration to put into murmur.ini.";
       };
+
+      environmentFile = mkOption {
+        type = types.nullOr types.path;
+        default = null;
+        example = "/var/lib/murmur/murmurd.env";
+        description = ''
+          Environment file as defined in <citerefentry>
+          <refentrytitle>systemd.exec</refentrytitle><manvolnum>5</manvolnum>
+          </citerefentry>.
+
+          Secrets may be passed to the service without adding them to the world-readable
+          Nix store, by specifying placeholder variables as the option value in Nix and
+          setting these variables accordingly in the environment file.
+
+          <programlisting>
+            # snippet of murmur-related config
+            services.murmur.password = "$MURMURD_PASSWORD";
+          </programlisting>
+
+          <programlisting>
+            # content of the environment file
+            MURMURD_PASSWORD=verysecretpassword
+          </programlisting>
+
+          Note that this file needs to be available on the host on which
+          <literal>murmur</literal> is running.
+        '';
+      };
     };
   };
 
@@ -256,14 +284,22 @@ in
       description = "Murmur Chat Service";
       wantedBy    = [ "multi-user.target" ];
       after       = [ "network-online.target "];
+      preStart    = ''
+        ${pkgs.envsubst}/bin/envsubst \
+          -o /run/murmur/murmurd.ini \
+          -i ${configFile}
+      '';
 
       serviceConfig = {
         # murmurd doesn't fork when logging to the console.
-        Type      = if forking then "forking" else "simple";
-        PIDFile   = mkIf forking "/run/murmur/murmurd.pid";
-        RuntimeDirectory = mkIf forking "murmur";
-        User      = "murmur";
-        ExecStart = "${pkgs.murmur}/bin/murmurd -ini ${configFile}";
+        Type = if forking then "forking" else "simple";
+        PIDFile = mkIf forking "/run/murmur/murmurd.pid";
+        EnvironmentFile = mkIf (cfg.environmentFile != null) cfg.environmentFile;
+        ExecStart = "${pkgs.murmur}/bin/murmurd -ini /run/murmur/murmurd.ini";
+        Restart = "always";
+        RuntimeDirectory = "murmur";
+        RuntimeDirectoryMode = "0700";
+        User = "murmur";
       };
     };
   };

nixos/tests/mumble.nix

@@ -5,6 +5,12 @@ let
     imports = [ ./common/x11.nix ];
     environment.systemPackages = [ pkgs.mumble ];
   };
+
+  # outside of tests, this file should obviously not come from the nix store
+  envFile = pkgs.writeText "nixos-test-mumble-murmurd.env" ''
+    MURMURD_PASSWORD=testpassword
+  '';
+
 in
 {
   name = "mumble";
@@ -14,8 +20,10 @@ in
 
   nodes = {
     server = { config, ... }: {
-      services.murmur.enable       = true;
+      services.murmur.enable = true;
       services.murmur.registerName = "NixOS tests";
+      services.murmur.password = "$MURMURD_PASSWORD";
+      services.murmur.environmentFile = envFile;
       networking.firewall.allowedTCPPorts = [ config.services.murmur.port ];
     };
 
@@ -30,8 +38,8 @@ in
     client1.wait_for_x()
     client2.wait_for_x()
 
-    client1.execute("mumble mumble://client1\@server/test &")
-    client2.execute("mumble mumble://client2\@server/test &")
+    client1.execute("mumble mumble://client1:testpassword\@server/test &")
+    client2.execute("mumble mumble://client2:testpassword\@server/test &")
 
     # cancel client audio configuration
     client1.wait_for_window(r"Audio Tuning Wizard")
@@ -63,8 +71,12 @@ in
     client2.send_chars("y")
 
     # Find clients in logs
-    server.wait_until_succeeds("journalctl -eu murmur -o cat | grep -q client1")
-    server.wait_until_succeeds("journalctl -eu murmur -o cat | grep -q client2")
+    server.wait_until_succeeds(
+        "journalctl -eu murmur -o cat | grep -q 'client1.\+Authenticated'"
+    )
+    server.wait_until_succeeds(
+        "journalctl -eu murmur -o cat | grep -q 'client2.\+Authenticated'"
+    )
 
     server.sleep(5)  # wait to get screenshot
     client1.screenshot("screen1")