Add new option "auth" to set credentials for Google Sheets API

README.md

@@ -93,16 +93,18 @@ export default {
 }
 ```
 
-## 🙊 What about secrets?
+## 🙊 How to provide credentials to access Google Spreadsheets API?
 
-Google Sheets API requires any kind of authentication since v4.
+Google Sheets API requires authentication since v4.
 `gdocs-table-downloader` is limited to the "service account" type.
-You should create such account in Google Console and then you have two options:
+You should create such account in Google Console, and then you have several options:
 
 1. Put `private_key` and `client_email` directly to a file specified by `--customOptions` param. See `customOptions.default.js` for example.
 2. Put `private_key` and `client_email` to ENV and read them from `process.env`
+3. Provide `--auth ./path-to-auth.json` to enable authentication. This file can be obtained from Google Console. See `auth-example.json` for example.
+   Only `private_key` and `client_email` fields are required.
 
-Frankly, you're not restricted to only these two methods. You can invent any
+Frankly, you're not restricted to only these methods. You can invent any
 type of "secrets storing", just ensure that `getGoogleAuthCredentials()` returns
 an object with two properties: `private_key` and `client_email`.
 

index.js

@@ -6,10 +6,10 @@ const mkdirp = require('mkdirp')
 const { getSheets } = require('./googleapis-client')
 const path = require('path')
 
-const { token, target, sheets, moduleType, muteEslintQuotes, customOptions } = require('./options')
+const { token, target, sheets, moduleType, muteEslintQuotes, customOptions, auth } = require('./options')
 
 ;(async() => {
-  const allSheetsWithTranslations = await loadTranslations(customOptions)
+  const allSheetsWithTranslations = await loadTranslations(customOptions, auth)
   saveTranslationsToFiles(allSheetsWithTranslations)
 
   log([
@@ -18,17 +18,35 @@ const { token, target, sheets, moduleType, muteEslintQuotes, customOptions } = r
   ].join(''))
 })()
 
-async function loadTranslations({ getGoogleAuthCredentials, getValueMapper }) {
-  const googleAuthCredentials = getGoogleAuthCredentials()
+async function loadTranslations({ getGoogleAuthCredentials, getValueMapper }, auth) {
+  console.log('auth', auth)
+  let googleAuthCredentials = getGoogleAuthCredentials()
 
-  if (!googleAuthCredentials || Object.values(googleAuthCredentials).join('').length === 0) {
+  // using auth from customOptions.getGoogleAuthCredentials()
+  if (!auth && (!googleAuthCredentials || Object.values(googleAuthCredentials).join('').length === 0)) {
     throw Error(
       'Google Auth Credentials are empty, function getGoogleAuthCredentials() from --customOptions file '
       + 'should return object with "private_key" and "client_email".'
       + `Instead, received: ${JSON.stringify(googleAuthCredentials, null, 2)}`
     )
   }
 
+  // using auth from auth.json
+  if (auth) {
+    if (!auth.private_key ||!auth.client_email) {
+      throw Error(
+        'Google Auth Credentials are empty, auth option '
+        + 'should be an object with "private_key" and "client_email".'
+        + `Instead, received: ${JSON.stringify(auth, null, 2)}`
+      )
+    }
+
+    googleAuthCredentials = {
+      client_email: auth.client_email,
+      private_key: auth.private_key
+    }
+  }
+
   const sheetsAsJson = await getSheets({
     credentials: googleAuthCredentials,
     spreadsheetId: token,

options.js

@@ -2,7 +2,7 @@ const fs = require('fs')
 const path = require('path')
 const yargs = require('yargs')
 
-const TRIGGER_DEFAULT_VALUE_FOR_CUSTOM_OPTIONS = 'non-existing-value-just-to-trigger-loading-of-default-custom-options'
+const TRIGGER_DEFAULT_VALUE_FOR_PATH_OPTION = 'non-existing-value-to-know-that-path-was-not-given'
 
 module.exports = yargs
   .example('$0 --token XYZ --target src/l10n/{sheet}/{locale}.js --moduleType AMD --sheets my_sheet,other_sheet',
@@ -35,8 +35,25 @@ module.exports = yargs
     choices:      ['AMD', 'ESM', 'JSON'],
     type:         'string'
   })
+  .option('auth', {
+    default:      TRIGGER_DEFAULT_VALUE_FOR_PATH_OPTION,
+    demandOption: false,
+    describe:     'Path to auth.json file that has "private_key" and "client_email" fields. This file can be downloaded from Google Console (see docs).',
+    type:         'string',
+    coerce:        value => {
+      const authPath = path.join(process.cwd(), value)
+      try {
+        fs.accessSync(authPath, fs.constants.R_OK)
+        return require(authPath)
+      } catch (_) {
+        if (value !== TRIGGER_DEFAULT_VALUE_FOR_PATH_OPTION) {
+          console.log(`Error! File "${value}" is not readable.`)
+        }
+      }
+    }
+  })
   .option('customOptions', {
-    default:      TRIGGER_DEFAULT_VALUE_FOR_CUSTOM_OPTIONS,
+    default:      TRIGGER_DEFAULT_VALUE_FOR_PATH_OPTION,
     demandOption: false,
     describe:     'Path to module with custom options',
     type:         'string',
@@ -50,7 +67,7 @@ module.exports = yargs
           ...require(userCustomFnPath)
         }
       } catch (_) {
-        if (pathToCustomOptions !== TRIGGER_DEFAULT_VALUE_FOR_CUSTOM_OPTIONS) {
+        if (pathToCustomOptions !== TRIGGER_DEFAULT_VALUE_FOR_PATH_OPTION) {
           console.log(`Error! Custom options file "${userCustomFnPath}" is not readable, using default options.`)
         }
         return defaultCustomOptions