modules/nixos/monitoring: add grafana

This reverts commit b7d0c7a4c5.

modules/nixos/monitoring/grafana.nix

@@ -0,0 +1,81 @@
+{
+  config,
+  inputs,
+  pkgs,
+  ...
+}:
+{
+  systemd.services.grafana.after = [ "prometheus.service" ];
+
+  age.secrets.grafana-client-secret = {
+    file = "${inputs.self}/secrets/grafana-client-secret.age";
+    owner = "grafana";
+  };
+
+  services.grafana = {
+    enable = true;
+    settings = {
+      analytics.reporting_enabled = false;
+      analytics.feedback_links_enabled = false;
+
+      "auth.anonymous".enabled = true;
+
+      # https://grafana.com/docs/grafana/latest/setup-grafana/configure-security/configure-authentication/github/
+      "auth.github" = {
+        enabled = true;
+        client_id = "ea6aa36488df8b2dede6";
+        client_secret = "$__file{${config.age.secrets.grafana-client-secret.path}}";
+        auth_url = "https://github.com/login/oauth/authorize";
+        token_url = "https://github.com/login/oauth/access_token";
+        api_url = "https://api.github.com/user";
+        allow_sign_up = true;
+        auto_login = false;
+        allowed_organizations = [ "nix-community" ];
+        role_attribute_strict = true;
+        allow_assign_grafana_admin = true;
+        role_attribute_path = "contains(groups[*], '@nix-community/admin') && 'GrafanaAdmin' || 'Editor'";
+      };
+
+      server = {
+        root_url = "https://monitoring.nix-community.org/grafana/";
+        domain = "monitoring.nix-community.org";
+        enforce_domain = true;
+        enable_gzip = true;
+      };
+
+      database = {
+        type = "postgres";
+        name = "grafana";
+        host = "/run/postgresql";
+        user = "grafana";
+      };
+
+      security.disable_initial_admin_creation = true;
+    };
+
+    provision.datasources.settings.datasources = [
+      {
+        name = "prometheus";
+        type = "prometheus";
+        isDefault = true;
+        url = "http://localhost:9090";
+      }
+    ];
+  };
+
+  services.telegraf.extraConfig.inputs.prometheus.urls = [
+    "http://localhost:3000/metrics"
+  ];
+
+  services.postgresql = {
+    enable = true;
+    package = pkgs.postgresql_17;
+    ensureDatabases = [ "grafana" ];
+    ensureUsers = [
+      {
+        name = "grafana";
+        ensureDBOwnership = true;
+      }
+    ];
+  };
+}