add Google IAP auth implementation (#1)

* add Google IAP auth implementation

.editorconfig

@@ -0,0 +1,9 @@
+root = true
+
+[*]
+charset = utf-8
+indent_style = space
+indent_size = 2
+end_of_line = lf
+insert_final_newline = true
+trim_trailing_whitespace = true

.eslintrc.js

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+module.exports = {
+  'env': {
+    'es6': true,
+    'node': true
+  },
+  'extends': [
+    'eslint:recommended',
+    'plugin:@typescript-eslint/eslint-recommended'
+  ],
+  'globals': {
+    'Atomics': 'readonly',
+    'SharedArrayBuffer': 'readonly'
+  },
+  'parser': '@typescript-eslint/parser',
+  'parserOptions': {
+    'ecmaVersion': 2017,
+    'sourceType': 'module'
+  },
+  'plugins': [
+    '@typescript-eslint'
+  ],
+  'ignorePatterns': ['dist/', 'node_modules/'],
+  'rules': {
+    'max-len': ['error', { 'code': 120 }],
+    'no-unused-vars': ['error', { 'args': 'none' }],
+    'indent': ['error', 2],
+    'linebreak-style': ['error', 'unix'],
+    'quotes': ['error', 'single'],
+    'semi': ['error', 'always']
+  }
+};

README.md

@@ -1,2 +1,51 @@
-# google-iap-auth-nodejs
+# @rtbhouse/google-iap-auth
+
 Helper library to perfrorm requests to OIDC-authenticated resources (Cloud Identity-Aware Proxy)
+
+## Installation
+
+```shell
+npm install @rtbhouse/google-iap-auth
+```
+
+## Usage
+
+To use this library you must have the following:
+
+- Identity Aware Proxy protected resource
+- Service account with permissions to read protected resource
+- OAuth credentials with key file in JSON format (
+  [more](https://cloud.google.com/iam/docs/creating-managing-service-account-keys#iam-service-account-keys-create-console)
+  on generating Service Account json keys)
+
+Example usage with [got](https://www.npmjs.com/package/got):
+
+```typescript
+import fs from 'fs';
+import got from "got";
+import { GoogleIapAuth } from "@rtbhouse/google-iap-auth";
+
+
+const keyStr = fs.readFileSync('key.json', 'utf-8');
+const keyData = JSON.parse(keyStr);
+const googleIapAuth = new GoogleIapAuth("<oauth_client_id>", keyData);
+const authorizedGot = got.extend({
+  hooks: {
+    beforeRequest: [
+      async options => {
+        options.headers.Authorization = `Bearer ${await googleIapAuth.getToken()}`;
+      }
+    ]
+  },
+  responseType: "json",
+  followRedirect: false,
+  mutableDefaults: true
+});
+
+(async () => {
+  const response = await authorizedGot(
+    "https://some.iap.protected.resource.com/"
+  );
+  console.log(response.statusCode);
+  console.log(response.body);
+})();

jestconfig.json

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+{
+  "preset": "ts-jest",
+  "rootDir": "./tests",
+  "testMatch": ["<rootDir>/**/*.ts"],
+  "moduleFileExtensions": ["ts", "tsx", "js", "jsx", "json", "node"]
+}