1  'use strict';
 2  
 3  const fs = require('fs');
 4  const path = require('path');
 5  const paths = require('./paths');
 6  
 7  // Make sure that including paths.js after env.js will read .env variables.
 8  delete require.cache[require.resolve('./paths')];
 9  
10  const NODE_ENV = process.env.NODE_ENV;
11  if (!NODE_ENV) {
12    throw new Error(
13      'The NODE_ENV environment variable is required but was not specified.'
14    );
15  }
16  
17  // https://github.com/bkeepers/dotenv#what-other-env-files-can-i-use
18  var dotenvFiles = [
19    `${paths.dotenv}.${NODE_ENV}.local`,
20    `${paths.dotenv}.${NODE_ENV}`,
21    // Don't include `.env.local` for `test` environment
22    // since normally you expect tests to produce the same
23    // results for everyone
24    NODE_ENV !== 'test' && `${paths.dotenv}.local`,
25    paths.dotenv,
26  ].filter(Boolean);
27  
28  // Load environment variables from .env* files. Suppress warnings using silent
29  // if this file is missing. dotenv will never modify any environment variables
30  // that have already been set.  Variable expansion is supported in .env files.
31  // https://github.com/motdotla/dotenv
32  // https://github.com/motdotla/dotenv-expand
33  dotenvFiles.forEach(dotenvFile => {
34    if (fs.existsSync(dotenvFile)) {
35      require('dotenv-expand')(
36        require('dotenv').config({
37          path: dotenvFile,
38        })
39      );
40    }
41  });
42  
43  // We support resolving modules according to `NODE_PATH`.
44  // This lets you use absolute paths in imports inside large monorepos:
45  // https://github.com/facebookincubator/create-react-app/issues/253.
46  // It works similar to `NODE_PATH` in Node itself:
47  // https://nodejs.org/api/modules.html#modules_loading_from_the_global_folders
48  // Note that unlike in Node, only *relative* paths from `NODE_PATH` are honored.
49  // Otherwise, we risk importing Node.js core modules into an app instead of Webpack shims.
50  // https://github.com/facebookincubator/create-react-app/issues/1023#issuecomment-265344421
51  // We also resolve them to make sure all tools using them work consistently.
52  const appDirectory = fs.realpathSync(process.cwd());
53  process.env.NODE_PATH = (process.env.NODE_PATH || '')
54    .split(path.delimiter)
55    .filter(folder => folder && !path.isAbsolute(folder))
56    .map(folder => path.resolve(appDirectory, folder))
57    .join(path.delimiter);
58  
59  // Grab NODE_ENV and REACT_APP_* environment variables and prepare them to be
60  // injected into the application via DefinePlugin in Webpack configuration.
61  const REACT_APP = /^REACT_APP_/i;
62  
63  function getClientEnvironment(publicUrl) {
64    const raw = Object.keys(process.env)
65      .filter(key => REACT_APP.test(key))
66      .reduce(
67        (env, key) => {
68          env[key] = process.env[key];
69          return env;
70        },
71        {
72          // Useful for determining whether we’re running in production mode.
73          // Most importantly, it switches React into the correct mode.
74          NODE_ENV: process.env.NODE_ENV || 'development',
75          // Useful for resolving the correct path to static assets in `public`.
76          // For example, <img src={process.env.PUBLIC_URL + '/img/logo.png'} />.
77          // This should only be used as an escape hatch. Normally you would put
78          // images into the `src` and `import` them in code to get their paths.
79          PUBLIC_URL: publicUrl,
80        }
81      );
82    // Stringify all values so we can feed into Webpack DefinePlugin
83    const stringified = {
84      'process.env': Object.keys(raw).reduce((env, key) => {
85        env[key] = JSON.stringify(raw[key]);
86        return env;
87      }, {}),
88    };
89  
90    return { raw, stringified };
91  }
92  
93  module.exports = getClientEnvironment;