Add notification channel: Slack

nixos/modules/monitoring/server/grafana.nix

@@ -121,6 +121,20 @@ in {
           name = "provisioned";
           options.path = ./grafana-dashboards;
         }];
+        # See https://grafana.com/docs/grafana/latest/administration/provisioning/#example-alert-notification-channels-config-file
+        notifiers = [{
+          uid = "slack-notifier-1";
+          name = "Slack";
+          type = "slack";
+          is_default = true;
+          send_reminder = false;
+          settings = {
+            uploadImage = true;
+          };
+          secure_settings = {
+            url = "https://hooks.slack.com/services/...";
+          };
+        }];
       };
     };