nixos/graphite: update docs, add graphite pager

nixos/modules/services/monitoring/graphite.nix

@@ -24,6 +24,8 @@ let
     GRAPHITE_URL = cfg.seyren.graphiteUrl;
   } // cfg.seyren.extraConfig;
 
+  pagerConfig = pkgs.writeText "alarms.yaml" cfg.pager.alerts;
+
   configDir = pkgs.buildEnv {
     name = "graphite-config";
     paths = lists.filter (el: el != null) [
@@ -83,13 +85,21 @@ in {
 
     api = {
       enable = mkOption {
-        description = "Whether to enable graphite api.";
+        description = ''
+          Whether to enable graphite api. Graphite api is lightweight alternative
+          to graphite web, with api and without dashboard. It's advised to use
+          grafana as alternative dashboard and influxdb as alternative to
+          graphite carbon.
+
+          For more information visit
+          <link xlink:href="http://graphite.readthedocs.org/en/1.0/index.html"/>
+        '';
         default = false;
         type = types.uniq types.bool;
       };
 
       finders = mkOption {
-        description = "List of finder plugins load.";
+        description = "List of finder plugins to load.";
         default = [];
         example = [ pkgs.python27Packages.graphite_influxdb ];
         type = types.listOf types.package;
@@ -301,20 +311,56 @@ in {
         '';
       };
     };
+
+    pager = {
+      enable = mkOption {
+        description = ''
+          Whether to enable graphite-pager service. For more information visit
+          <link xlink:href="https://github.com/seatgeek/graphite-pager"/>
+        '';
+        default = false;
+        type = types.uniq types.bool;
+      };
+
+      redisUrl = mkOption {
+        description = "Redis connection string.";
+        default = "redis://localhost:${toString config.services.redis.port}/";
+        type = types.str;
+      };
+
+      graphiteUrl = mkOption {
+        description = "URL to your graphite service.";
+        default = "http://${cfg.web.host}:${toString cfg.web.port}";
+        type = types.str;
+      };
+
+      alerts = mkOption {
+        description = "Alerts configuration for graphite-pager.";
+        default = ''
+          alerts:
+            - target: constantLine(100)
+              warning: 90
+              critical: 200
+              name: Test
+        '';
+        example = literalExample ''
+          pushbullet_key: pushbullet_api_key 
+          alerts:
+            - target: stats.seatgeek.app.deal_quality.venue_info_cache.hit
+              warning: .5
+              critical: 1
+              name: Deal quality venue cache hits
+        '';
+        type = types.lines;
+      };
+    };
   };
 
   ###### implementation
 
-  config = mkIf (
-    cfg.carbon.enableAggregator ||
-    cfg.carbon.enableCache ||
-    cfg.carbon.enableRelay ||
-    cfg.web.enable ||
-    cfg.api.enable ||
-    cfg.seyren.enable
-  ) {
+  config = mkMerge [
+    (mkIf cfg.carbon.enableCache {
       systemd.services.carbonCache = {
-      enable = cfg.carbon.enableCache;
         description = "Graphite Data Storage Backend";
         wantedBy = [ "multi-user.target" ];
         after = [ "network-interfaces.target" ];
@@ -331,7 +377,9 @@ in {
           chown -R graphite:graphite ${cfg.dataDir}
         '';
       };
+    })
 
+    (mkIf cfg.carbon.enableAggregator {
       systemd.services.carbonAggregator = {
         enable = cfg.carbon.enableAggregator;
         description = "Carbon Data Aggregator";
@@ -344,9 +392,10 @@ in {
           Group = "graphite";
         };
       };
+    })
 
+    (mkIf cfg.carbon.enableRelay {
       systemd.services.carbonRelay = {
-      enable = cfg.carbon.enableRelay;
         description = "Carbon Data Relay";
         wantedBy = [ "multi-user.target" ];
         after = [ "network-interfaces.target" ];
@@ -357,9 +406,16 @@ in {
           Group = "graphite";
         };
       };
+    })
 
+    (mkIf (cfg.carbon.enableCache || cfg.carbon.enableAggregator || cfg.carbon.enableRelay) {
+      environment.systemPackages = [
+        pkgs.pythonPackages.carbon
+      ];
+    })
+
+    (mkIf cfg.web.enable {
       systemd.services.graphiteWeb = {
-      enable = cfg.web.enable;
         description = "Graphite Web Interface";
         wantedBy = [ "multi-user.target" ];
         after = [ "network-interfaces.target" ];
@@ -397,8 +453,11 @@ in {
         '';
       };
 
+      environment.systemPackages = [ pkgs.python27Packages.graphite_web ];
+    })
+
+    (mkIf cfg.api.enable { 
       systemd.services.graphiteApi = {
-      enable = cfg.api.enable;
         description = "Graphite Api Interface";
         wantedBy = [ "multi-user.target" ];
         after = [ "network-interfaces.target" ];
@@ -430,9 +489,10 @@ in {
           fi
         '';
       };
+    })
 
+    (mkIf cfg.seyren.enable {
       systemd.services.seyren = {
-      enable = cfg.seyren.enable;
         description = "Graphite Alerting Dashboard";
         wantedBy = [ "multi-user.target" ];
         after = [ "network-interfaces.target" "mongodb.service" ];
@@ -451,14 +511,31 @@ in {
         '';
       };
 
-    services.mongodb.enable = mkDefault cfg.seyren.enable;
+      services.mongodb.enable = mkDefault true;
+    })
 
-    environment.systemPackages = [
-      pkgs.pythonPackages.carbon
-      pkgs.python27Packages.graphite_web
-      pkgs.python27Packages.waitress
-    ];
+    (mkIf cfg.pager.enable {
+      systemd.services.graphitePager = {
+        description = "Graphite Pager Alerting Daemon";
+        wantedBy = [ "multi-user.target" ];
+        after = [ "network-interfaces.target" "redis.service" ];
+        environment = {
+          REDIS_URL = cfg.pager.redisUrl;
+          GRAPHITE_URL = cfg.pager.graphiteUrl;
+        };
+        serviceConfig = {
+          ExecStart = "${pkgs.pythonPackages.graphite_pager}/bin/graphite-pager --config ${pagerConfig}";
+          User = "graphite";
+          Group = "graphite"; 
+        };
+      };
 
+      services.redis.enable = mkDefault true;
+
+      environment.systemPackages = [ pkgs.pythonPackages.graphite_pager ];
+    })
+
+    {
       users.extraUsers = singleton {
         name = "graphite";
         uid = config.ids.uids.graphite;
@@ -466,5 +543,6 @@ in {
         home = dataDir;
       };
       users.extraGroups.graphite.gid = config.ids.gids.graphite;
-  };
+    }
+  ];
 }