nixos/conman: init module

Adding a service for the conman package

Changes to conman service as per review

nixos/doc/manual/release-notes/rl-2511.section.md

@@ -84,6 +84,8 @@
 
 - [paisa](https://github.com/ananthakumaran/paisa), a personal finance tracker and dashboard. Available as [services.paisa](#opt-services.paisa.enable).
 
+- [conman](https://github.com/dun/conman), a serial console management program. Available as [services.conman](#opt-services.conman.enable).
+
 ## Backward Incompatibilities {#sec-release-25.11-incompatibilities}
 
 <!-- To avoid merge conflicts, consider adding your item at an arbitrary place in the list instead. -->

nixos/modules/module-list.nix

@@ -806,6 +806,7 @@
   ./services/misc/clipcat.nix
   ./services/misc/clipmenu.nix
   ./services/misc/confd.nix
+  ./services/misc/conman.nix
   ./services/misc/cpuminer-cryptonight.nix
   ./services/misc/db-rest.nix
   ./services/misc/devmon.nix

nixos/modules/services/misc/conman.nix

@@ -0,0 +1,89 @@
+{
+  config,
+  lib,
+  pkgs,
+  ...
+}:
+
+{
+  options = {
+    services.conman = {
+      enable = lib.mkEnableOption ''
+        Enable the conman Console manager.
+
+        Either `configFile` or `config` must be specified.
+      '';
+      package = lib.mkPackageOption pkgs "conman" { };
+
+      configFile = lib.mkOption {
+        type = lib.types.nullOr lib.types.path;
+        default = null;
+        example = "/run/secrets/conman.conf";
+        description = ''
+          The absolute path to the configuration file.
+
+          Either `configFile` or `config` must be specified.
+
+          See <https://github.com/dun/conman/wiki/Man-5-conman.conf#files>.
+        '';
+      };
+      config = lib.mkOption {
+        type = lib.types.nullOr lib.types.lines;
+        default = null;
+        example = ''
+          server coredump=off
+          server keepalive=on
+          server loopback=off
+          server timestamp=1h
+
+          # global config
+          global log="/var/log/conman/%N.log"
+          global seropts="9600,8n1"
+          global ipmiopts="U:<user>,P:<password>"
+        '';
+        description = ''
+          The configuration object.
+
+          Either `configFile` or `config` must be specified.
+
+          See <https://github.com/dun/conman/wiki/Man-5-conman.conf#files>.
+        '';
+      };
+    };
+  };
+  meta.maintainers = with lib.maintainers; [
+    frantathefranta
+  ];
+
+  config =
+    let
+      cfg = config.services.conman;
+      configFile =
+        if cfg.configFile != null then
+          cfg.configFile
+        else
+          pkgs.writeTextFile {
+            name = "conman.conf";
+            text = cfg.config;
+          };
+    in
+    lib.mkIf cfg.enable {
+      assertions = [
+        {
+          assertion =
+            (cfg.configFile != null) && (cfg.config == null) || (cfg.configFile == null && cfg.config != null);
+          message = "Either but not both `configFile` and `config` must be specified for conman.";
+        }
+      ];
+      environment.systemPackages = [ cfg.package ];
+      systemd.services.conmand = {
+        description = "serial console management program";
+        documentation = [ "man:conman(8)" ];
+        wantedBy = [ "multi-user.target" ];
+        serviceConfig = {
+          ExecStart = "${cfg.package}/bin/conmand -F -c ${configFile}";
+          KillMode = "process";
+        };
+      };
+    };
+}