🌱

Author: mars

.gitignore

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+node_modules

README.md

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+Heroku JS Runtime Env
+=====================
+Make single-page javascript apps (SPA) honor runtime environment variables.
+
+Normally javascript apps are compiled into a bundle before being deployed. During this compile phase, environment variables may be embedded in the javascript bundle, such as with [Webpack DefinePlugin](https://webpack.github.io/docs/list-of-plugins.html#defineplugin). If you're hosting on a [12-factor](https://12factor.net) platform like [Heroku](https://www.heroku.com), these embedded values may go stale when setting new [config vars](https://devcenter.heroku.com/articles/config-vars), promoting through a [pipeline](https://devcenter.heroku.com/articles/pipelines), or [rolling back](https://devcenter.heroku.com/articles/releases#rollback) to a previous release.
+
+In coordination with the build process, this tiny module provides a mechanism to inject runtime environment variables into a javascript bundle without recompiling.
+
+Usage
+-----
+
+🚧 🚧 🚧

index.js

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+// Capture environment as module variable to allow testing.
+var originalEnv = process.env;
+// This Mustache template tag should be rendered/replaced with the environment in production.
+var templatedEnv = '{{REACT_APP_VARS_AS_JSON}}';
+
+
+// A function returning the runtime environment, so that 
+// JSON parsing & errors occur at runtime instead of load time.
+function runtimeEnv() {
+  var env;
+
+  if (originalEnv.NODE_ENV === 'production') {
+    try {
+      env = JSON.parse(templatedEnv);
+    } catch(error) {
+      throw new Error(
+        'Runtime env vars could not be parsed. '+
+        'Content of `REACT_APP_VARS_AS_JSON` is `'+templatedEnv+'` '+
+        'Ensure `node_modules/@mars/heroku-js-runtime-env/index.js` '+
+        'is rendered as a Mustache template.'
+      );
+    }
+
+  } else {
+    env = originalEnv;
+  }
+
+  return env;
+}
+
+module.exports = runtimeEnv;

package.json

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+{
+  "name": "@mars/heroku-js-runtime-env",
+  "version": "1.0.0",
+  "description": "Runtime env var support for static javascript apps on Heroku",
+  "main": "index.js",
+  "scripts": {
+    "test": "mocha"
+  },
+  "repository": {
+    "type": "git",
+    "url": "git+https://github.com/mars/heroku-js-runtime-env.git"
+  },
+  "keywords": [
+    "heroku",
+    "environment",
+    "variable",
+    "env",
+    "var",
+    "config",
+    "runtime",
+    "javascript"
+  ],
+  "author": "Mars Hall",
+  "license": "MIT",
+  "bugs": {
+    "url": "https://github.com/mars/heroku-js-runtime-env/issues"
+  },
+  "homepage": "https://github.com/mars/heroku-js-runtime-env#readme",
+  "devDependencies": {
+    "mocha": "^3.1.2",
+    "rewire": "^2.5.2",
+    "should": "^11.1.1"
+  }
+}

test/development-test.js

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+var rewire = require('rewire')
+var should = require('should')
+
+describe('in development', function() {
+  var runtimeEnv
+
+  beforeEach(function() {
+    runtimeEnv = rewire('../')
+    runtimeEnv.__set__('originalEnv', { NODE_ENV: 'development'})
+  });
+
+  it('contains value of `process.env`', function() {
+    runtimeEnv().should.be.an.instanceOf(Object).and.have.property('NODE_ENV')
+  })
+
+})

test/production-test.js

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+var rewire = require('rewire')
+var should = require('should')
+
+describe('in production', function() {
+  var runtimeEnv
+
+  beforeEach(function() {
+    runtimeEnv = rewire('../')
+    runtimeEnv.__set__('originalEnv', { NODE_ENV: 'production'})
+  })
+
+  it('throws error when Mustache tag is not rendered', function() {
+    runtimeEnv.should.throw(/Runtime env vars could not be parsed/)
+  })
+
+  describe('with Mustache template replacements', function() {
+    beforeEach(function() {
+      runtimeEnv.__set__('templatedEnv', '{ "REACT_APP_USER": "🦄"}')
+    })
+
+    it('contains value of the runtime environment', function() {
+      runtimeEnv().should.be.an.instanceOf(Object).and.have.property('REACT_APP_USER', '🦄')
+    })
+  })
+
+})