How to configure 【Azure】Application Gateway to support multiple App services?

Question

I have 3 app services on Azure, like

• app1.azurewebsites.net
• app2.azurewebsites.net
• app3.azurewebsites.net

And I have created an Application gateway in front of them, with WAF enabled.

And I'm going to setup 3 custom domain and SSL certificate for each of the app service. What I want to achieve is like below:

• visit https://app1.mydomain.com= >Application Gateway=>app1.azurewebsites.net
• visit https://app2.mydomain.com= >Application Gateway=>app2.azurewebsites.net
• visit https://app3.mydomain.com= >Application Gateway=>app3.azurewebsites.net

Is this possible with only 1 application gateway to support multiple domain? Or I must purchase 3 gateways, which is 3 times cost. Basically I only want to use the WAF to protect my site.

Answer 1

Your ask is possible with one Application Gateway.

Here is the configuration that you need to set up.

Listener 1 (app1.mydomain.com) --> HTTP Setting 1 (Check Use App Service check box) --> Backend Pool 1(app1.azurewebsites.net)

Listener 2 (app2.mydomain.com) --> HTTP Setting 2 (Check Use App Service check box) --> Backend Pool 2(app2.azurewebsites.net)

Listener 3 (app3.mydomain.com) --> HTTP Setting 3 (Check Use App Service check box) --> Backend Pool 3(app3.azurewebsites.net)

So, you need 3 Listener , 3 HTTP Settings, 3 Backend Pool and 3 rules.

You need to create probes for each HTTP Setting and you enable HTTPS protocol and also check pick hostname from Backend HTTP Settings.

Reference: https://docs.microsoft.com/en-us/azure/application-gateway/configure-web-app-portal