Connecting one app Service to another using private link

Question

I am trying to connect my apps together privately. Here is the setup:

1. Webapp FrontEnd (Node 18) :
2. Webapp Backend (.NET7)
3. webApp CosmosDb (Azure Cosmos DB account)

Network Configuration:

1. the frontend and backend are in the same app service plan Linux Basic: B2.
2. frontEnd is public exposed
3. backend is public blocked but has private endpoint
4. frontEnd is trying to call backend using the https://backend-dev.azurewebsites.net
5. All the subnets have the Micrsoft.Web service added. The frontend subnet has the webfarms delegation
6. backend has the CORS with "*" added.
7. The DNS are setup for all private links

Status:

• From the Frontend SCM I can do a curl to this backend url. I get proper response
• from browser I am getting 403
  • Request has been blocked by CORS policy: Response to preflight request doesn't pass access control check: No 'Access-Control-Allow-Origin' header is present on the requested resource.
  • tried with "https://backend-dev.privatelink.azurewebsites.net" in frontnend code but did not work

Can someone help me out please. I tried the setups in this post as well. No luck

here is the resource graph

nslookup from frontend ssh

Answer 1

One thing I would check - are the private DNS zones linked to the vNet? This has cost me more pain than anything else in setups like this. Does the frontend resolve backend-dev.azurewebsites.net to the expected private IP?