hainich/monitoring: init prometheus

hosts/hainich/configuration.nix

@@ -17,6 +17,7 @@
     ./services/gitlab-runner.nix
     ./services/lantifa.nix
     ./services/syncthing.nix
+    ./services/monitoring.nix
   ];
   boot.loader.grub.enable = true;
   boot.loader.grub.version = 2;

hosts/hainich/services/monitoring.nix

@@ -0,0 +1,42 @@
+{ config, lib, pkgs, ... }:
+
+{
+  services.prometheus = {
+    enable = true;
+    webExternalUrl = "https://stats.hacc.space";
+    exporters = {
+      dovecot = {
+        enable = true;
+        scopes = [ "user" "global" ];
+        socketPath = "/var/run/dovecot2/old-stats";
+      };
+      nginx.enable = true;
+      node.enable = true;
+      postfix = {
+        enable = true;
+        systemd.enable = true;
+      };
+      rspamd.enable = true;
+    };
+    scrapeConfigs = (lib.mapAttrsToList (name: val:
+      {
+        job_name = "${name}-${config.networking.hostName}";
+        static_configs = [{
+          targets = [ "localhost:${toString val.port}" ];
+          labels.host = config.networking.hostName;
+        }];
+      }
+    ) (lib.filterAttrs (_: val: val.enable) config.services.prometheus.exporters));
+  };
+
+  services.dovecot2.extraConfig = ''
+    mail_plugins = $mail_plugins old_stats
+    service old-stats {
+      unix_listener old-stats {
+        user = dovecot-exporter
+        group = dovecot-exporter
+        }
+    }
+  '';
+  services.nginx.statusPage = true;
+}