Runtime env var support for static javascript apps on Heroku
npm install @mars/heroku-js-runtime-envHeroku JS Runtime Env
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Use runtime environment variables in bundled/minified javascript apps.
Usage
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Designed for create-react-app-buildpack. See its documentation to use this module for Runtime configuration.
Background
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Normally javascript apps are compiled into a bundle before being deployed. During this build phase, environment variables may be embedded in the javascript bundle, such as with Webpack DefinePlugin.
When hosting on a 12-factor platform like Heroku, these embedded values may go stale when setting new config vars or promoting through a pipeline.
How Does It Work?
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When developing your app, use Runtime environment variables from create-react-app-buildpack.
Then, each time the app starts-up on Heroku, a .profile.d script (installed from the buildpack) is executed which fills in a JSON placeholder in the JavaScript bundle with the runtime environment variables. The result is 🍃fresh runtime environment variables in the production javascript bundle without recompiling.