Azure App Service Private Endpoint Returning 404

Question

I have an Azure App Service that I'll call "mywebapp." The public URL works correctly, and when I run:

curl -I http://mywebapp.azurewebsites.net

I get the expected response:

HTTP/1.1 302 Found
Content-Length: 145
Content-Type: text/html; charset=utf-8
Date: Thu, DD Nov YYYY HH:MM:SS GMT
Access-Control-Allow-Headers: Content-Type
Access-Control-Allow-Methods: GET, OPTIONS
Cache-Control: private
Location: /Account/Logon?ReturnUrl=%2f
Set-Cookie: omissis;Path=/;HttpOnly;Domain=mywebapp.azurewebsites.net
Strict-Transport-Security: max-age=63072000; includeSubDomains
X-XSS-Protection: 1
X-Content-Type-Options: nosniff
X-Frame-Options: SAMEORIGIN
Referrer-Policy: strict-origin-when-cross-origin
Content-Security-Policy: omissis

The public endpoint works perfectly.

Now, I created a virtual network and a private endpoint. The private DNS zone is privatelink.azurewebsites.net. When I check the recordset, I deduce that the hostname to use is mywebapp.privatelink.azurewebsites.net.

From the Azure virtual network, I perform some tests:

I run:

nslookup mywebapp.privatelink.azurewebsites.net

And I get:

Server:         127.0.0.11
Address:        127.0.0.11#53
Non-authoritative answer:
Name:   mywebapp.privatelink.azurewebsites.net
Address: 10.0.0.5

So far, everything seems fine. The DNS name resolves correctly, and the private IP is correct.

Next, I run:

curl -I http://mywebapp.privatelink.azurewebsites.net

But I get:

HTTP/1.1 404 Site Not Found
Content-Length: 2667
Connection: close
Content-Type: text/html
Date: Thu, DD Nov YYYY HH:MM:SS GMT

This is not what I expect. I've tried many different configurations to get a proper result, but I always end up with this 404 Site Not Found error.

Could someone help me troubleshoot this issue?

Answer 1

Hi Francesco,

When you are connecting via private endpoint you should use same FQDN, e.g. mywebapp.azurewebsites.net

On your VNet it will resolve to private IP address of your private endpoint and when you are on public network it will resolve to the public IP address of your webapp.

Please click Accept Answer and upvote if the above was helpful.

Thanks.

-TP