Add Light and Dark url's for Grafana to the index page (#304)

* light and dark mode url links

* fix the set key

Author: slim-bean

prometheus-ksonnet/lib/config.libsonnet

@@ -9,9 +9,16 @@
     // Overrides for the nginx frontend for all these services.
     admin_services: std.prune([
       {
-        title: 'Grafana',
+        title: 'Grafana (Light)',
         path: 'grafana',
-        params: '/?search=open',
+        params: '/?search=open&theme=light',
+        url: 'http://grafana.%(namespace)s.svc.%(cluster_dns_suffix)s/' % $._config,
+        allowWebsockets: true,
+      },
+      {
+        title: 'Grafana (Dark)',
+        path: 'grafana',
+        params: '/?search=open&theme=dark',
         url: 'http://grafana.%(namespace)s.svc.%(cluster_dns_suffix)s/' % $._config,
         allowWebsockets: true,
       },

prometheus-ksonnet/lib/nginx.libsonnet

@@ -45,7 +45,7 @@
     local vars = {
       location_stanzas: [
         buildLocation(service)
-        for service in $._config.admin_services
+        for service in std.set($._config.admin_services, function(s) s.url)
       ],
       locations: std.join('\n', self.location_stanzas),
       link_stanzas: [