204s are accepted...

files/core_alerts.yml

@@ -123,8 +123,8 @@ groups:
     annotations:
       summary: Prometheus DNS Domain (instance {{ $labels.instance }} {{ $labels.domain }})
       description: "The Domain Check has failed. The DNS server may have crashed.\n VALUE = {{ $value }}\n  LABELS = {{ $labels }}"
-  - alert: HTTP2 status code is not 200 
-    expr: (avg without(job)(probe_http_status_code)) != 200
+  - alert: HTTP status code is not 200 or 204
+    expr: ((avg without(job)(probe_http_status_code)) != 200) and ((avg without(job)(probe_http_status_code)) != 204)
     for: 2m
     labels:
       severity: critical