prometheus: include url as a label

for coverage maps

monitoring/prometheus.jsonnet

@@ -33,15 +33,18 @@ local services = [
     [
       {
         local hosts = hosts_by_scheme[scheme],
+        local url = hosts[host][0],
+        local role = hosts[host][1],
         job_name: "%s-%s" % [scheme, service],
         metrics_path: "/metrics/%s" % service,
         scheme: scheme,
         static_configs: [
           {
-            targets: [hosts[host][0]],
+            targets: [url],
             labels: {
               instance: host,
-              role: hosts[host][1],
+              url: url,
+              role: role,
               service: service,
             },
           } for host in std.objectFields(hosts)