Enable prometheus, add loki config example, we don't have a global log system so it's not useful though

nixos/server/package-configs/dashboard/prometheus/default.nix

@@ -0,0 +1,38 @@
+{
+  config,
+  pkgs,
+  ...
+}: {
+  services.prometheus = {
+    enable = true;
+    port = 9001;
+    # Export the current system metrics
+    exporters = {
+      node = {
+        enable = true;
+        enabledCollectors = ["systemd"];
+        port = 9002;
+      };
+    };
+    scrapeConfigs = [
+      # Scrape the current system
+      {
+        job_name = "GrafanaService system";
+        static_configs = [
+          {
+            targets = ["127.0.0.1:9002"];
+          }
+        ];
+      }
+      # Scrape the Loki service
+      # {
+      #   job_name = "Loki service";
+      #   static_configs = [
+      #     {
+      #       targets = ["127.0.0.1:3100"];
+      #     }
+      #   ];
+      # }
+    ];
+  };
+}