As I mentioned earlier I’ve built a shiny app to visualize the development of SARS-CoV-2 in Germany.

Running it locally works very well. But how to deploy an app in the web?

There is a free service at shinyapps.io where you can host your shiny app.

But the free plan offers only a fixed amount of memory. The data my app is reading consumes more memory than I get there. So I was looking for a way my app can detect whether it is running at shinyapps.io or not. Depending on the result of this check I can offer different features to the user (such as updating the data).

It turns out that there is an environment variable set at shinyapps.io:

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Sys.getenv("R_CONFIG_ACTIVE") == "shinyapps"

So depending on the value of R_CONFIG_ACTIVE you can change the behaviour of your app.