server.js: rewritten to use Promises

src/node/server.js

@@ -22,7 +22,6 @@
  */
 
 var log4js = require('log4js')
-  , async = require('async')
   , NodeVersion = require('./utils/NodeVersion')
   ;
 
@@ -49,52 +48,37 @@ stats.gauge('memoryUsage', function() {
   return process.memoryUsage().rss;
 });
 
-var settings
-  , db
-  , plugins
-  , hooks;
+/*
+ * no use of let or await here because it would cause startup
+ * to fail completely on very early versions of NodeJS
+ */
 var npm = require("npm/lib/npm.js");
 
-async.waterfall([
-  // load npm
-  function(callback) {
-    npm.load({}, function(er) {
-      callback(er);
-    });
-  },
-
-  // load everything
-  function(callback) {
-    settings = require('./utils/Settings');
-    db = require('./db/DB');
-    plugins = require("ep_etherpad-lite/static/js/pluginfw/plugins");
-    hooks = require("ep_etherpad-lite/static/js/pluginfw/hooks");
+npm.load({}, function() {
+  var settings = require('./utils/Settings');
+  var db = require('./db/DB');
+  var plugins = require("ep_etherpad-lite/static/js/pluginfw/plugins");
+  var hooks = require("ep_etherpad-lite/static/js/pluginfw/hooks");
   hooks.plugins = plugins;
-    callback();
-  },
 
-  // initalize the database
-  function (callback) {
-    db.init(callback);
-  },
-
-  function(callback) {
-    plugins.update(callback);
-  },
-
-  function (callback) {
+  db.init()
+    .then(plugins.update)
+    .then(function() {
       console.info("Installed plugins: " + plugins.formatPluginsWithVersion());
       console.debug("Installed parts:\n" + plugins.formatParts());
       console.debug("Installed hooks:\n" + plugins.formatHooks());
 
       // Call loadSettings hook
       hooks.aCallAll("loadSettings", { settings: settings });
-    callback();
-  },
 
       // initalize the http server
-  function (callback) {
       hooks.callAll("createServer", {});
-    callback(null);
+    })
+    .catch(function(e) {
+      console.error("exception thrown: " + e.message);
+      if (e.stack) {
+        console.log(e.stack);
       }
-]);
+      process.exit(1);
+    });
+});