Shiny Server - Serve only folders with app.R

My shiny-server path has subfolders with files that should not be served. ie, it's like

/srv/shiny-server/
    content_folder/
        subfolder1/
            file_that_should_not_be_served.csv
            folder_that_should_not_be_served/
                some_files_and_folders
            inner_folder/
                app.R
                supporting_files

I need to serve http://localhost:3838/content_folder/subfolder1/inner_folder/ as shiny application, but need to throw some error (ideally notfound or unauthorized) when other folders/files are opened. eg, http://localhost:3838/content_folder/subfolder1/folder_that_should_not_be_served/ and http://localhost:3838/content_folder/subfolder1/file_that_should_not_be_served.csv should fail.

Is there a way to do this? I'm open to using proxy servers if that would help...