Can't plug Azure datasource with Grafana running on Cloud Run

What happened: Loading subscription from Azure when you try to configure Azure datasource, give you weird response from /api/datasources/proxy/1/azuremonitor/subscriptions/

What you expected to happen : Loading subscription

How to reproduce it (as minimally and precisely as possible) :

  1. Run Grafana in GCP Cloud Run (default configuration)
  2. Add datasource azure (fill tenant id, client secret, client id)
  3. Open Chrome/Firefox console (tab network)
  4. Click on “Load Subscriptions”
  5. Look the response

Anything else we need to know? : This is a very weird issue BUT I’ve try many things

  1. this happens ONLY in Cloud Run. With the same Grafana image local or gcp compute instance -> no issue
  2. I’ve try to load subscription from azure SDK + using httputil.ReserveProxy (like Grafana does) -> I can get the Azure response without issue
  3. Other datasource (Loki/Stackdriver/Cloudwatch/Prometheus) work well
  4. If I use a wrong client ID for Azure, I get a good response (valid JSON with 401 status code)

Furthermore, I can give access to a cloud run environnement if necessary or access to Azure (privately of course)

Request send by the front

Response received (obviously not a valid json)