App Service with VNET integration cannot connect to HTTP endpoint within the same VNET

Question

I have integrate my App service web app to an existing VNET in same region following this guidance: https://docs.microsoft.com/en-us/azure/app-service/web-sites-integrate-with-vnet

Within that VNET, there is already a Elasticsearch cluster running on VM scale sets and I can connect to Elasticsearch from a jumpbox VM within the same VNET via the private Ip http://10.0.0.4.

But the App service is not able not connect to the Elasticsearch via the private Ip address, following is error message:

System.Net.Http.HttpRequestException: An error occurred while sending the request. ---> System.Net.WebException: Unable to connect to the remote server ---> System.Net.Sockets.SocketException: A non-recoverable error occurred during a database lookup

Is this scenario supported by App service VNET integration? If yes, do I miss something? Or how to troubleshoot the root cause?

Answer 1

App service VNET integration could support that scenario, read Connecting Azure App services to Elasticsearch in this blog. "With all this in place, the web application should be able to communicate with the cluster."

In that example, it uses Gateway required VNet Integration. Theoretically, the regional VNet Integration should also do the trick. You can go to your KUDU console for troubleshooting. Also, you could check the following first.