diff --git a/installers/charm/prometheus/config.yaml b/installers/charm/prometheus/config.yaml
index a5f5e8a..c1c0fb9 100644
--- a/installers/charm/prometheus/config.yaml
+++ b/installers/charm/prometheus/config.yaml
@@ -35,6 +35,11 @@
       of Keystone, it may need to be configured to handle the requested size.
       Note: if set to 0, there is no limit.
     default: 0
+  ingress_class:
+    type: string
+    description: |
+      Ingress class name. This is useful for selecting the ingress to be used
+      in case there are multiple ingresses in the underlying k8s clusters.
   ingress_whitelist_source_range:
     type: string
     description: |