Add alertmanager config

hosts/flora-6/apps/prometheus.nix

@@ -1,6 +1,4 @@
 { config
-, lib
-, pkgs
 , flake
 , ...
 }: {
@@ -65,5 +63,39 @@
         }];
       }
     ];
+
+    alertmanager = {
+      enable = true;
+      # port = 9093; # Default
+      webExternalUrl = "https://alerts.pub.solar";
+      # environmentFile = "${config.age.secrets.nachtigall-alertmanager-envfile.path}";
+      configuration = {
+
+        route = {
+          receiver = "all";
+          group_by = [ "instance" ];
+          group_wait = "30s";
+          group_interval = "2m";
+          repeat_interval = "24h";
+        };
+
+        receivers = [{
+          name = "all";
+          # Email config documentation: https://prometheus.io/docs/alerting/latest/configuration/#email_config
+          email_configs = [{
+            send_resolved = true;
+            to = "TODO";
+            from = "alerts@pub.solar";
+            smarthost = "TODO";
+            auth_username = "TODO";
+            auth_password_file = "${config.age.secrets.nachtigall-alertmanager-smtp-password.path}";
+            require_tls = true;
+          }];
+          # TODO:
+          # For matrix notifications, look into: https://github.com/pinpox/matrix-hook and add a webhook
+          #   webhook_configs = [ { url = "http://127.0.0.1:11000/alert"; } ];
+        }];
+      };
+    };
   };
 }