feat: add alerting for amz ebs server and websites blackbox

hosts/web-arm/modules/grafana/alerting/service/amzebs_nginx_down.nix

@@ -0,0 +1,58 @@
+{ lib, pkgs, config, ... }:
+{
+  grafanaAlertRuleDefinitions = [
+    {
+      uid = "amzebs-nginx-service-down-alert-uid";
+      title = "Nginx Service Down on amzebs-01";
+      condition = "C";
+      data = [
+        {
+          refId = "A";
+          relativeTimeRange = {
+            from = 300;
+            to = 0;
+          };
+          datasourceUid = "vm-datasource-uid";
+          model = {
+            editorMode = "code";
+            expr = "node_systemd_unit_state{state=\"active\", name=\"nginx.service\", instance=\"amzebs-01:9100\"} OR on() vector(0)";
+            hide = false;
+            intervalMs = 1000;
+            legendFormat = "__auto";
+            maxDataPoints = 43200;
+            range = true;
+            refId = "A";
+          };
+        }
+        {
+          refId = "B";
+          datasourceUid = "__expr__";
+          model = {
+            type = "reduce";
+            expression = "A";
+            reducer = "last";
+          };
+        }
+        {
+          refId = "C";
+          datasourceUid = "__expr__";
+          model = {
+            type = "math";
+            expression = "$B < 1";
+          };
+        }
+      ];
+      noDataState = "Alerting";
+      execErrState = "Alerting";
+      for = "5m";
+      annotations = {
+        description = "Nginx service is down on amzebs-01";
+        summary = "Nginx Service Down on amzebs-01";
+      };
+      labels = {
+        severity = "critical";
+        host = "amzebs-01";
+      };
+    }
+  ];
+}