Using Environment Variables

This section focuses on setting environment variables during the image’s run time.

Environment variable are a great tool to make your code dynamic and flexiable. Setting environment variable during the run time enables to pass useful information to the container, such as passwords and credentials or any other information. For example, let’s add to the r-base image an environment variable named MY_VAR with the value of MY_VALUE:

docker run --interactive --tty \
 -e MY_VAR="MY_VALUE" \
 -v ~/Personal/tutorials/r-medicine-vscode-workshop/scripts/:/scripts \
 -v ~/Personal/tutorials/r-medicine-vscode-workshop/data/:/data \
 rocker/r-base

As before, this will open an R session, and we can use the Sys.getenv function to print the variable value:

 WARNING: The requested image's platform (linux/amd64) does not match the detected host platform (linux/arm64/v8) and no specific platform was requested

R version 4.4.0 (2024-04-24) -- "Puppy Cup"
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Platform: x86_64-pc-linux-gnu

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> Sys.getenv("MY_VAR")
[1] "MY_VALUE"