Enterprise Framework

<rewrite> 

<rules> 

<rule name="HTTP To HTTPS Redirect Behind App Gtwy" stopProcessing="true"> 

<match url="^(.*)$" ignoreCase="false" /> 

<conditions logicalGrouping="MatchAny"> 

<add input="{HTTP_X_FORWARDED_PROTO}" pattern="^http$" ignoreCase="false" /> 

</conditions> 

<action type="Redirect" url="https://{SERVER_NAME}{URL}" redirectType="Found" /> 

</rule> 

</rules> 

</rewrite>

You can also do this HTTP to HTTPS redirect through the Application Gateway using PowerShell.

https://docs.microsoft.com/en-us/azure/application-gateway/application-gateway-configure-redirect-powershell