I recently blogged about generating a version.txt file on every build via Visual Studio. This solution is fine if you are building from you local machine and using Web Deploy to deploy to Azure, but if you have a github webhook and are using kudu, the VS Post Build Events are not executed.
The easiest way I found to generate a version.txt file for every deployment is to add a post deployment action to your Web App/App Service.
Create a file within the /site/deployments/tools/PostDeploymentActions/ folder of your App Service (you may need to create that folder). You can name the file whatever you'd like, I chose `generategitversionfile.cmd`. The file should contain at least the following line:
git rev-parse HEAD > "..\wwwroot\version.txt"
This command will be executed within the context of the `/site/repository` directory, that's why we need a more fully qualified path for where to write the file.
Now, after every kudu deploy, a new version.txt file will be created that contains the current git comment hash.
Hope this helps,