Our SharePoint Hosted App has a configuration file needs to be updated during App upgrade. I understand that event-handling code can't be used for SharePoint Hosted App. It will be painful for an administrator to visit each App to update the configuration file manually if the app has been deployed to hundreds of subsites.
I was thinking to have the app home page to update the file automatically when a user access the app first time, but it can run into permission issue as not all users can write the file. Now I am thinking of creating a tool for the administrator to update all sites at once, but I don't feel it is a good solution.