Setting up a predictable path for execution of a shiny app on AWS

Paul, If Shiny Server is installed on the AWS instance, it will be running on port 3838 by default. The port is configurable, but you should be access your applications at a fixed port. Your application must be in a directory that is known to Shiny Server. By default this is /srv/shiny-server directory. But it is also configurable. Please refer to the Admin Guide for more information:

http://docs.rstudio.com/shiny-server/