创建 Azure 事件网格 webhook 订阅失败 TLS 握手

Question

Trying to create a webhook subscription to an Event Grid topic fails with an error reported in the Azure portal:

Deployment has failed with the following error..."Webhook validation handshake failed for https://xxx.xxx.xxx.xxx:10443/event . Http POST request failed with response code Unknown

My webhook is a .NET core test app using a Kestrel server. I can see from logging that there is an incoming connection from Azure when I try to create the subscription, but this is immediately followed by a disconnect.

Microsoft.AspNetCore.Server.Kestrel: Debug: Connection id "0HMCE876DPTD6" accepted. Microsoft.AspNetCore.Server.Kestrel: Debug: Connection id "0HMCE876DPTD6" started. Microsoft.AspNetCore.Server.Kestrel.Transport.Sockets: Debug: Connection id "0HMCE876DPTD6" received FIN. Microsoft.AspNetCore.Server.Kestrel.Transport.Sockets: Debug: Connection id "0HMCE876DPTD6" sending FIN because: "The client closed the connection." Microsoft.AspNetCore.Server.Kestrel: Debug: Connection id "0HMCE876DPTD6" disconnecting. Microsoft.AspNetCore.Server.Kestrel: Debug: Connection id "0HMCE876DPTD6" stopped.

It appears that there is an error during the TLS handshake. Are there any specific requirements for TLS for the webhook. I'm using the default certificate ("ASP.NET Core HTTPS development certificate"). This won't be trusted by Azure - is that a problem?

Answer 1

As per the documentation Using self-signed certificates for validation isn't supported. You need to use a signed certificate from a commercial certificate authority (CA) instead. You can also go through this troubleshooting document if it helps.