Add NixOS module for the Riemann dashboard server

nixos/modules/misc/ids.nix

@@ -145,6 +145,7 @@
       mlmmj = 135;
       neo4j = 136;
       riemann = 137;
+      riemanndash = 138;
 
       # When adding a uid, make sure it doesn't match an existing gid. And don't use uids above 399!
 
@@ -263,6 +264,7 @@
       siproxd = 134;
       mlmmj = 135;
       riemann = 137;
+      riemanndash = 138;
 
       # When adding a gid, make sure it doesn't match an existing uid. And don't use gids above 399!
 

nixos/modules/module-list.nix

@@ -171,6 +171,7 @@
   ./services/monitoring/munin.nix
   ./services/monitoring/nagios.nix
   ./services/monitoring/riemann.nix
+  ./services/monitoring/riemann-dash.nix
   ./services/monitoring/smartd.nix
   ./services/monitoring/statsd.nix
   ./services/monitoring/systemhealth.nix

nixos/modules/services/monitoring/riemann-dash.nix

@@ -0,0 +1,79 @@
+{ config, pkgs, ... }:
+
+with pkgs;
+with pkgs.lib;
+
+let
+
+  cfg = config.services.riemann-dash;
+
+  conf = writeText "config.rb" ''
+    riemann_base = "${cfg.dataDir}"
+    config.store[:ws_config] = "#{riemann_base}/config/config.json"
+    ${cfg.config}
+  '';
+
+  launcher = writeScriptBin "riemann-dash" ''
+    #!/bin/sh
+    exec ${rubyLibs.riemann_dash}/bin/riemann-dash ${conf}
+  '';
+
+in {
+
+  options = {
+
+    services.riemann-dash = {
+      enable = mkOption {
+        type = types.bool;
+        default = false;
+        description = ''
+          Enable the riemann-dash dashboard daemon.
+        '';
+      };
+      config = mkOption {
+        type = types.lines;
+        description = ''
+          Contents added to the end of the riemann-dash configuration file.
+        '';
+      };
+      dataDir = mkOption {
+        type = types.str;
+        default = "/var/riemann-dash";
+        description = ''
+          Location of the riemann-base dir. The dashboard configuration file is
+          is stored to this directory. The directory is created automatically on
+          service start, and owner is set to the riemanndash user.
+        '';
+      };
+    };
+
+  };
+
+  config = mkIf cfg.enable {
+
+    users.extraGroups.riemanndash.gid = config.ids.gids.riemanndash;
+
+    users.extraUsers.riemanndash = {
+      description = "riemann-dash daemon user";
+      uid = config.ids.uids.riemanndash;
+      group = "riemanndash";
+    };
+
+    systemd.services.riemann-dash = {
+      wantedBy = [ "multi-user.target" ];
+      wants = [ "riemann.service" ];
+      after = [ "riemann.service" ];
+      preStart = ''
+        mkdir -p ${cfg.dataDir}/config
+        chown -R riemanndash:riemanndash ${cfg.dataDir}
+      '';
+      serviceConfig = {
+        User = "riemanndash";
+        ExecStart = "${launcher}/bin/riemann-dash";
+        PermissionsStartOnly = true;
+      };
+    };
+
+  };
+
+}