diff --git a/app-init.js b/app-init.js
index be5627af..319fa0c3 100644
--- a/app-init.js
+++ b/app-init.js
@@ -39,12 +39,24 @@ const sessionStore = new MySQLStore({
 */
 
 
-const mongoCredentials = {
-  host: process.env.MONGO_DB_HOST || 'localhost',
-  port: process.env.MONGO_DB_PORT || 27017,
+function getMongoDbConnectionString () {
+  // Allow the connection string builder to be overridden by an environment variable
+  if (process.env.MONGO_DB_CONNECTION_STRING) {
+    return process.env.MONGO_DB_CONNECTION_STRING;
+  }
+  
+  const host = process.env.MONGO_DB_HOST || 'localhost';
+  const port = process.env.MONGO_DB_PORT || 27017;
+  const user = process.env.MONGO_DB_USER || '';
+  const password = process.env.MONGO_DB_PASSWORD || '';
+  const authSource = process.env.MONGO_DB_AUTHSOURCE || '';
+  
+  const useAuth = user && password;
+  
+  return `mongodb://${useAuth ? `${user}:${password}@` : ''}${host}:${port}/sessions${authSource ? `?authSource=${authSource}` : ''}`;
 }
 
-const url = 'mongodb://'+ mongoCredentials.host +':'+mongoCredentials.port+'/sessions';
+const url = getMongoDbConnectionString();
 
 const sessionStore =  new MongoStore({
     url: url,