✨ Replace dotenv with custom implementation (#426)

* ✨ Replace dotenv with custom implementation

* ✅ Remove dotenv reference

packages/env/package.json

@@ -20,8 +20,5 @@
   },
   "devDependencies": {
     "mock-require": "^3.0.3"
-  },
-  "dependencies": {
-    "dotenv": "^10.0.0"
   }
 }

packages/env/src/dotenv.js

@@ -1,25 +1,76 @@
-const dotenv = require('dotenv');
+import fs from 'fs';
 
-// mimic dotenv-rails file hierarchy
-// https://github.com/bkeepers/dotenv#what-other-env-files-can-i-use
-export function config() {
-  let {
-    NODE_ENV: env,
-    PERCY_DISABLE_DOTENV: disable
-  } = process.env;
+// Heavily inspired by dotenv-rails
+// https://github.com/bkeepers/dotenv
 
+// matches each valid line of a dotenv file
+const LINE_REG = new RegExp([
+  // key with optional export
+  '^\\s*(?:export\\s+)?(?<key>[\\w.]+)',
+  // separator
+  '(?:\\s*=\\s*?|:\\s+?)(?:',
+  // single quoted value or
+  '\\s*(?<squote>\')(?<sval>(?:\\\\\'|[^\'])*)\'|',
+  // double quoted value or
+  '\\s*(?<dquote>")(?<dval>(?:\\\\"|[^"])*)"|',
+  // unquoted value
+  '(?<uval>[^#\\r\\n]+))?',
+  // optional comment
+  '\\s*(?:#.*)?$'
+].join(''), 'gm');
+
+// interpolate variable substitutions
+const INTERPOLATE_REG = /(.?)(\${?([a-zA-Z0-9_]+)?}?)/g;
+// expand newlines
+const EXPAND_CRLF_REG = /\\(?:(r)|n)/g;
+// unescape characters
+const UNESC_CHAR_REG = /\\([^$])/g;
+
+export function load() {
   // don't load dotenv files when disabled
-  if (disable) return;
+  if (process.env.PERCY_DISABLE_DOTENV) return;
+  let { NODE_ENV } = process.env;
 
+  // dotenv filepaths ordered by priority
   let paths = [
-    env && `.env.${env}.local`,
-    // .env.local is not loaded in test environments
-    env === 'test' ? null : '.env.local',
-    env && `.env.${env}`,
+    NODE_ENV && `.env.${NODE_ENV}.local`,
+    NODE_ENV !== 'test' && '.env.local',
+    NODE_ENV && `.env.${NODE_ENV}`,
     '.env'
-  ].filter(Boolean);
+  ];
 
+  // load each dotenv file synchronously
   for (let path of paths) {
-    dotenv.config({ path });
+    try {
+      let src = fs.readFileSync(path, { encoding: 'utf-8' });
+
+      // iterate over each matching line
+      for (let { groups: match } of src.matchAll(LINE_REG)) {
+        let value = match.sval ?? match.dval ?? match.uval ?? '';
+
+        // if double quoted, expand newlines
+        if (match.dquote) {
+          value = value.replace(EXPAND_CRLF_REG, (_, r) => r ? '\r' : '\n');
+        }
+
+        // unescape characters
+        value = value.replace(UNESC_CHAR_REG, '$1');
+
+        // if not single quoted, interpolate substitutions
+        if (!match.squote) {
+          value = value.replace(INTERPOLATE_REG, (_, pre, ref, key) => {
+            if (pre === '\\') return ref; // escaped reference
+            return pre + (process.env[key] ?? '');
+          });
+        }
+
+        // set process.env if not already
+        if (!Object.prototype.hasOwnProperty.call(process.env, match.key)) {
+          process.env[match.key] = value;
+        }
+      }
+    } catch (e) {
+      // silent error
+    }
   }
 }

packages/env/src/index.js

@@ -1,2 +1,2 @@
 export { default } from './environment';
-require('./dotenv').config();
+require('./dotenv').load();

packages/env/test/dotenv.test.js

@@ -6,7 +6,6 @@ describe('dotenv files', () => {
   beforeAll(() => {
     env = process.env;
     mock('fs', { readFileSync: path => dotenvs[path] ?? '' });
-    mock.reRequire('dotenv');
     mock.reRequire('../src/dotenv');
   });
 
@@ -30,6 +29,13 @@ describe('dotenv files', () => {
     expect(process.env).toHaveProperty('TEST_3', '3');
   });
 
+  it('does not override existing environment variables', () => {
+    process.env.TEST_1 = 'uno';
+    mock.reRequire('../src');
+
+    expect(process.env).toHaveProperty('TEST_1', 'uno');
+  });
+
   it('loads environment specific .env and .env.local files', () => {
     dotenvs['.env.dev'] = 'TEST_3=dev_3';
     dotenvs['.env.dev.local'] = 'TEST_2=dev_two';
@@ -56,4 +62,44 @@ describe('dotenv files', () => {
     mock.reRequire('../src');
     expect(process.env).toEqual({ PERCY_DISABLE_DOTENV: 'true' });
   });
+
+  it('expands newlines within double quotes', () => {
+    dotenvs['.env'] = 'TEST_NEWLINES="foo\nbar\r\nbaz\\nqux\\r\\nxyzzy"';
+    mock.reRequire('../src');
+
+    expect(process.env).toHaveProperty('TEST_NEWLINES', 'foo\nbar\r\nbaz\nqux\r\nxyzzy');
+  });
+
+  it('interpolates variable substitutions', () => {
+    // eslint-disable-next-line no-template-curly-in-string
+    dotenvs['.env'] += '\nTEST_4=$TEST_1${TEST_2}\nTEST_5=$TEST_4${TEST_3}four';
+    mock.reRequire('../src');
+
+    expect(process.env).toHaveProperty('TEST_4', '1two');
+    expect(process.env).toHaveProperty('TEST_5', '1two3four');
+  });
+
+  it('interpolates undefined variables with empty strings', () => {
+    // eslint-disable-next-line no-template-curly-in-string
+    dotenvs['.env'] += '\nTEST_TWO=2 > ${TEST_ONE}\nTEST_THREE=';
+    mock.reRequire('../src');
+
+    expect(process.env).not.toHaveProperty('TEST_ONE');
+    expect(process.env).toHaveProperty('TEST_TWO', '2 > ');
+    expect(process.env).toHaveProperty('TEST_THREE', '');
+  });
+
+  it('does not interpolate single quoted strings', () => {
+    dotenvs['.env'] += "\nTEST_STRING='$TEST_1'";
+    mock.reRequire('../src');
+
+    expect(process.env).toHaveProperty('TEST_STRING', '$TEST_1');
+  });
+
+  it('does not interpolate escaped dollar signs', () => {
+    dotenvs['.env'] += '\nTEST_ESC=\\$TEST_1';
+    mock.reRequire('../src');
+
+    expect(process.env).toHaveProperty('TEST_ESC', '$TEST_1');
+  });
 });

yarn.lock

@@ -3636,11 +3636,6 @@ dot-prop@^6.0.1:
   dependencies:
     is-obj "^2.0.0"
 
-dotenv@^10.0.0:
-  version "10.0.0"
-  resolved "https://registry.yarnpkg.com/dotenv/-/dotenv-10.0.0.tgz#3d4227b8fb95f81096cdd2b66653fb2c7085ba81"
-  integrity sha512-rlBi9d8jpv9Sf1klPjNfFAuWDjKLwTIJJ/VxtoTwIR6hnZxcEOQCZg2oIL3MWBYw5GpUDKOEnND7LXTbIpQ03Q==
-
 duplexer@^0.1.1:
   version "0.1.2"
   resolved "https://registry.yarnpkg.com/duplexer/-/duplexer-0.1.2.tgz#3abe43aef3835f8ae077d136ddce0f276b0400e6"