Change configuration on azure website when using GIT to deploy

How do I configure my website to use either test or release configuration when I'm deploying using GIT? I can configure the branch I want to use, but the the build configuration.

How do I change my Azure Web config?

If you want to change web. config files you can use the Azure portal, there is a tool called "App Service Editor" in preview or Kudu that lets you edit any of the files you've deployed.

The best way to do this is to use a custom deployment script, as described in this post.

Once you do that, you have a lot more control over how your app is built. In this case, you can just tweak the msbuild command like it runs to use whatever configuration you want, much like you'd do if you ran msbuild on your local machine.