Shiny server debugging

[sebsilas]

Hi Peter,

It can be quite difficult to debug apps on Shiny Server when using the psychTestR framework (although perhaps this is a general Shiny problem). Whilst I usually test everything locally first before uploading, sometimes new errors only present themselves on the server.

The issue is that if something crashes when running a psychTestR experiment on Shiny Server, you don't get an informative error. In the browser console, you usually get:

Or Shiny might say, "ERROR: An error has occurred. Check your logs or contact the app author for clarification."

However, when you get those kind of errors, app logs are not produced (ie., /var/log/shiny-server/blah.log).

Ideally, somewhere you want to see what you'd normally see in your R console when testing locally.

Perhaps I am missing a trick or a new feature would be required.

Can you recommend a way to do this, or if it requires a new feature, point me in the right direction to work on it?

All the best,
Seb

[pmcharrison]

Hi @syntheso I think it's worth spending some more time looking at the standard Shiny procedures here. I have to look these up each time unfortunately! But there's quite a lot of information on Google. I know there are several log files, for example. There's also an option in the server config to give 'real' error messages on the frontend, which is really handy for debugging.