feat: enable postgres exporter, group monitoring programs

nixos/configuration.nix

@@ -29,8 +29,8 @@
     ./programs/prosody.nix
     ./programs/yggdrasil.nix
 
-    ./programs/grafana.nix
-    ./programs/prometheus.nix
+    ./monitoring/grafana.nix
+    ./monitoring/prometheus.nix
   ];
 
   nix = {

nixos/databases/postgres.nix

@@ -13,6 +13,7 @@
       "freshrss"
       "prosody"
       "grafana"
+      "postgres-exporter"
     ];
     ensureUsers = [
       {
@@ -60,6 +61,11 @@
         ensureDBOwnership = true;
         ensureClauses.login = true;
       }
+      {
+        name = "postgres-exporter";
+        ensureDBOwnership = true;
+        ensureClauses.login = true;
+      }
     ];
     identMap = ''
        # ArbitraryMapName systemUser DBUser

nixos/monitoring/prometheus.nix

@@ -9,6 +9,11 @@
         enabledCollectors = [ "systemd" ];
         port = 55012;
       };
+      postgres = {
+        enable = true;
+        port = 55014;
+        dataSourceName = "user=postgres-exporter database=postgres-exporter host=/run/postgresql sslmode=disable";
+      };
     };
     
     scrapeConfigs = [
@@ -25,6 +30,12 @@
           targets = [ "127.0.0.1:55013" ];
         }];
       }
+      {
+        job_name = "postgres";
+        static_configs = [{
+          targets = [ "127.0.0.1:${toString config.services.prometheus.exporters.postgres.port}" ];
+        }];
+      }
     ];
   };
 }