Inlined package requires to save boot time and memory

no issue

- following on from f4fb0fcbaa,
  this commit moves around some package requires in Ghost
- these are often niche packages that do something in a subsystem of
  Ghost, and are not necessarily be needed to boot the application
- these packages use non-negligible CPU and memory when they are
  required, so it makes sense to lazy-require them
- the concern here is that we obscure the code too much by moving
  random requires further into code, but the changes are small and the
  improvements big
- this commit bring the boot time since 4.19.0 down ~31% and initial
  memory usage down by a total of ~12%

core/server/lib/mobiledoc.js

@@ -3,7 +3,6 @@ const errors = require('@tryghost/errors');
 const logging = require('@tryghost/logging');
 const config = require('../../shared/config');
 const storage = require('../adapters/storage');
-const imageTransform = require('@tryghost/image-transform');
 
 let cardFactory;
 let cards;
@@ -34,6 +33,7 @@ module.exports = {
                 siteUrl: config.get('url'),
                 imageOptimization: config.get('imageOptimization'),
                 canTransformImage(storagePath) {
+                    const imageTransform = require('@tryghost/image-transform');
                     const {ext} = path.parse(storagePath);
 
                     // NOTE: the "saveRaw" check is smelly

core/server/models/user.js

@@ -8,7 +8,6 @@ const limitService = require('../services/limits');
 const tpl = require('@tryghost/tpl');
 const errors = require('@tryghost/errors');
 const security = require('@tryghost/security');
-const {gravatar} = require('../lib/image');
 const {pipeline} = require('@tryghost/promise');
 const validatePassword = require('../lib/validate-password');
 const permissions = require('../services/permissions');
@@ -191,6 +190,8 @@ User = ghostBookshelf.Model.extend({
         // If the user's email is set & has changed & we are not importing
         if (self.hasChanged('email') && self.get('email') && !options.importing) {
             tasks.gravatar = (function lookUpGravatar() {
+                const {gravatar} = require('../lib/image');
+
                 return gravatar.lookup({
                     email: self.get('email')
                 }).then(function (response) {

core/server/services/bulk-email/mailgun.js

@@ -1,6 +1,5 @@
 const _ = require('lodash');
 const {URL} = require('url');
-const mailgun = require('mailgun-js');
 const logging = require('@tryghost/logging');
 const configService = require('../../../shared/config');
 const settingsCache = require('../../../shared/settings-cache');
@@ -8,6 +7,7 @@ const settingsCache = require('../../../shared/settings-cache');
 const BATCH_SIZE = 1000;
 
 function createMailgun(config) {
+    const mailgun = require('mailgun-js');
     const baseUrl = new URL(config.baseUrl);
 
     return mailgun({

core/server/services/mega/post-email-serializer.js

@@ -1,5 +1,4 @@
 const _ = require('lodash');
-const juice = require('juice');
 const template = require('./template');
 const settingsCache = require('../../../shared/settings-cache');
 const urlUtils = require('../../../shared/url-utils');
@@ -20,6 +19,7 @@ const ALLOWED_REPLACEMENTS = ['first_name'];
 const formatHtmlForEmail = function formatHtmlForEmail(html) {
     const juiceOptions = {inlinePseudoElements: true};
 
+    const juice = require('juice');
     let juicedHtml = juice(html, juiceOptions);
 
     // convert juiced HTML to a DOM-like interface for further manipulation

core/server/update-check.js

@@ -1,7 +1,6 @@
 const _ = require('lodash');
 
 const api = require('./api');
-const GhostMailer = require('./services/mail').GhostMailer;
 const config = require('../shared/config');
 const urlUtils = require('./../shared/url-utils');
 const jobsService = require('./services/jobs');
@@ -10,8 +9,6 @@ const request = require('@tryghost/request');
 const ghostVersion = require('@tryghost/version');
 const UpdateCheckService = require('@tryghost/update-check-service');
 
-const ghostMailer = new GhostMailer();
-
 /**
  * Initializes and triggers update check
  *
@@ -25,6 +22,9 @@ module.exports = async () => {
         return;
     }
 
+    const {GhostMailer} = require('./services/mail');
+    const ghostMailer = new GhostMailer();
+
     const updateChecker = new UpdateCheckService({
         api: {
             settings: {

core/server/web/oauth/app.js

@@ -1,7 +1,5 @@
 const debug = require('@tryghost/debug')('web:oauth:app');
 const {URL} = require('url');
-const passport = require('passport');
-const GoogleStrategy = require('passport-google-oauth20').Strategy;
 const express = require('../../../shared/express');
 const urlUtils = require('../../../shared/url-utils');
 const shared = require('../shared');
@@ -36,6 +34,10 @@ module.exports = function setupOAuthApp() {
      */
     function googleOAuthMiddleware(clientId, secret) {
         return (req, res, next) => {
+            // Lazy-required to save boot time
+            const passport = require('passport');
+            const GoogleStrategy = require('passport-google-oauth20').Strategy;
+
             const adminURL = urlUtils.urlFor('admin', true);
 
             //Create the callback url to be sent to Google

core/server/web/well-known.js

@@ -1,19 +1,19 @@
 const express = require('../../shared/express');
 const settings = require('../../shared/settings-cache');
-const jose = require('node-jose');
-
-const dangerousPrivateKey = settings.get('ghost_private_key');
-const keyStore = jose.JWK.createKeyStore();
-const keyStoreReady = keyStore.add(dangerousPrivateKey, 'pem');
-
-const getSafePublicJWKS = async () => {
-    await keyStoreReady;
-    return keyStore.toJSON();
-};
 
 module.exports = function setupWellKnownApp() {
     const wellKnownApp = express('well-known');
 
+    const jose = require('node-jose');
+    const dangerousPrivateKey = settings.get('ghost_private_key');
+    const keyStore = jose.JWK.createKeyStore();
+    const keyStoreReady = keyStore.add(dangerousPrivateKey, 'pem');
+
+    const getSafePublicJWKS = async () => {
+        await keyStoreReady;
+        return keyStore.toJSON();
+    };
+
     wellKnownApp.get('/jwks.json', async (req, res) => {
         const jwks = await getSafePublicJWKS();
         res.json(jwks);

core/shared/html-to-plaintext.js

@@ -1,6 +1,6 @@
-const htmlToText = require('html-to-text');
-
 module.exports = function htmlToPlaintext(html) {
+    const htmlToText = require('html-to-text');
+
     return htmlToText.fromString(html, {
         wordwrap: 80,
         ignoreImage: true,

core/shared/labs.js

@@ -1,6 +1,5 @@
 const _ = require('lodash');
 const Promise = require('bluebird');
-const SafeString = require('express-hbs').SafeString;
 const errors = require('@tryghost/errors');
 const logging = require('@tryghost/logging');
 const tpl = require('@tryghost/tpl');
@@ -87,6 +86,7 @@ module.exports.enabledHelper = function enabledHelper(options, callback) {
 
     logging.error(new errors.DisabledFeatureError(errDetails));
 
+    const {SafeString} = require('express-hbs');
     errString = new SafeString(`<script>console.error("${_.values(errDetails).join(' ')}");</script>`);
 
     if (options.async) {