Rockwell Schrock

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Text Adventures With direnv

February 11, 2023

If you use direnv to configure your local development environment, you might run into a situation where one set of environment variables does not cut it.

For example, a front-end JS application might need to connect to number of different server environments, such as local development, staging, or production.

Here's a little secret: .envrc is just a shell script. There's nothing magic about it.

Armed with that knowledge, here's an iteration of .envrc that prompts the user for the environment when switching into the project directory:

# .envrc
export COMMON_ENV=here

echo -n "Configure [d]evelopment, [s]taging, or [p]roduction? "
read

case $REPLY in 
  p)
    echo 'Configuring production environment'
    export BASE_URL=https://example.com
    ;;
  s)
    echo 'Configuring staging environment'
    export BASE_URL=https://staging.example.com
    ;;
  *)
    echo 'Configuring development environment'
    export BASE_URL=http://localhost:4000
    ;;
esac

Now, when you cd into the project directory:

❯ cd myapp
direnv: loading ~/myapp/.envrc
Configure [d]evelopment, [s]taging, or [p]roduction? d
Configuring development environment
direnv: export +COMMON_ENV +BASE_URL

Just don't enter the wrong input, or you might be eaten by a grue.