feat: add prometheus config

services/prometheus.nix

@@ -0,0 +1,24 @@
+{lib, ...}:
+let 
+  serv = import ../config/services.nix;
+  conf = lib.attrsets.mapAttrsToList (name: cfg: {
+    job_name = name;
+
+    scrape_interval = cfg.scrape_interval;
+
+    metrics_path = cfg.metrics_path;
+    
+    static_configs = cfg.static_configs;
+  }) serv.prometheus.scrapeConfigs;
+in
+{
+  services.prometheus = {
+    enable = true;
+
+    scrapeConfigs = conf;
+
+    port = serv.prometheus.port;
+  };
+
+  networking.firewall.allowedTCPPorts = [ serv.prometheus.port ];
+}