Where should <allowedServerVariables> tag live in Azure Website applicationHost.config?
You have to create a applicationHost.xdt file under the site folder d:\home\site\applicationHost.xdt with this content:
<?xml version="1.0"?> <configuration xmlns:xdt="http://schemas.microsoft.com/XML-Document-Transform"> <system.webServer> <rewrite> <allowedServerVariables> <add name="HTTP_X_USE_HTTPS" xdt:Transform="InsertIfMissing" xdt:Locator="Match(name)" /> </allowedServerVariables> </rewrite> </system.webServer></configuration>Now you can use the new variable in your web.config file
<?xml version="1.0" encoding="UTF-8"?><configuration> <system.webServer> <rewrite> <rules> <rule name="Proxy"> <serverVariables> <set name="HTTP_X_USE_HTTPS" value="{HTTPS}"/> </serverVariables> </rule> </rules> </rewrite> </system.webServer></configuration>See also https://azure.microsoft.com/en-us/documentation/articles/web-sites-transform-extend/ or https://github.com/projectkudu/kudu/wiki/Xdt-transform-samples