README.md

release-env

release-env is a small package that exposes environment variables from Release to your application at run time. Any environment variable that starts with RELEASE_ will be exposed at run time via process.env.

Motivation

Release allows for the creation of ephemeral staging environments, meaning there are new URLs for services every time an environment is created. If your Javascript application needs to talk to a service which has been given a generated URL then that URL needs to be exposed via an environment variable. Without server side rendering, these environment variables need to be available and exposed when the application starts or when a static build is built.

The idea behind release-env comes from Create React App and how REACT_APP_ environment variables are exposed via process.env(see Adding Custom Environment Variables).

Create React App

If you are using Create React App it is not necessary to use release-env as you can achieve the functionality of this package by mapping Release environment variables to REACT_APP_ variables. Please see the Release docs on Mapping Environment Variables.

Installtion

# with npm 
npm install release-env
 
# or with Yarn 
yarn add release-env

Adding to Webpack

In your webpack.config.js file import the getReleaseEnvironmentVariables function.

const getReleaseEnvironmentVariables = require("release-env");

Inside of the module.exports, access the Release environment variables.

module.exports = function(webpackEnv) {
  const releaseEnv = getReleaseEnvironmentVariables();
  ...
}

Define a new plugin with the Release environment variables.

plugins: [
  new webpack.DefinePlugin(releaseEnv.stringified),
  ...
]

Usage

In your application the environment variables will be accessible via process.env.RELEASE_ENV_VAR. An example would be to be define a configuration file to store API paths.

// config.js

export default {
  API_URL: process.env.RELEASE_BACKEND_INGRESS_URL,
};

// api.js

import axios from "axios";
import config from "./config";

const client = axios.create({
  baseURL: config.API_URL,
  headers: {
    "Content-Type": "application/json"
  }
});

export default client;