R-Shiny apps can’t access system-wide environment variables by design. How to work with them anyway? I got some suggestions to my question on Mastodon from the #rstats community. In the end, together with my colleague Sebi, I implemented this solution:
1.Assume a machine with two environment variables called MY_ENV_VAR and MY_ENV_VAR2
2.Commit a env (not .env!) that references the systemwide variables:
MY_ENV_VAR=“${MY_ENV_VAR}“MY_ENV_VAR2=“${MY_ENV_VAR2}“
3. Copy the env file to specific shiny app’s folder as .env: cp env srv/shiny-server/my-app/.env
4. Allow the shiny user to read the .env file: chown shiny srv/shiny-server/my-app/.env
5. Read .env file in the Shiny app with base::readRenviron(".env")
2 Kommentare
R Shiny apps can actually access system-wide environment variables. Where did you read it was not the case „by design“? I’m curious.
Run `Sys.getenv()` and you will see the list of preloaded environment variables.
Even if a variable is not available, you can use `system(„echo $VARIABLE“, intern = TRUE)` to get any system variable.
Also the common way to define environment variables in R (and Shiny) is to create a file named `.Renviron` at the root of the project directory (or in the home directory of the user) and define the variables there.
A best practice is also to „chmod 600“ the environment file since they tend to contain secrets.
Hey Charles,
thanks for your comment!
That Shiny apps cannot access system-wide environment variables by design I infered this from these posts:
– https://forum.posit.co/t/how-to-access-os-environment-variable-from-shiny-apps-server-r/23822/2
– https://groups.google.com/g/shiny-discuss/c/nNs0kztwdWo/m/90InjZXfAPEJ (Joe Cheng)
`Sys.getenv()` does not (always) work, there are plenty of stackoverflow posts out there, e.g. https://stackoverflow.com/questions/36853408/sys-getenv-returns-empty-in-shiny-apps
Plus my own experience. I am more than happy if this is not the case.
I know, that `.Renviron` are used in a common way. My usecase is a Kubernetes cluster with databases that I want to access with a Shiny app and the credentials are stored in systemwide environment variables. Copy pasting them first to an `.Renviron` does not make sense to me or is basically the same workflow I proposed.
Thanks for the `chmod 600`!