diff --git a/prometheus/defaults.yaml b/prometheus/defaults.yaml
index 4164795..de2bf54 100644
--- a/prometheus/defaults.yaml
+++ b/prometheus/defaults.yaml
@@ -10,6 +10,7 @@ prometheus:
       config_file: /etc/prometheus/prometheus.yml
       storage:
         local_path: /var/lib/prometheus/metrics
+      url: https://prometheus.io/docs/introduction/overview/
   alertmanager:
     version: 0.15.3.linux-amd64
     install_dir: /opt