How to Create a Cloud Storage Server

Web File Manager

The Web File Server object transforms your Mako Server into a powerful and secure storage system, letting you access and share files from any connected computer or device in the world. You can either access it through a Web browser or mount it as a WebDAV drive, in which case it works like a local drive.

The combined WebDAV Server and Web File Manager is called the Web File Server. In this tutorial we will show how to programmatically create a Web File Server (WFS) object. However, if you just want a quick way to enable the WebDAV server on a private network without authentication, simply create the following mako.conf configuration file:

   lockdir="/tmp/.LOCK", -- Linux,Mac,QNX.
   noauth=true -- No authentication needed.

Enabling the combined WebDAV Server and Web File Manager using mako.conf.

The video above shows how to connect a Windows and Mac computer to a WebDAV server.

The WFS uses some internal magic to provide a Web File Manager and WebDAV server on the same URL. You can also create a DAV only object. The benefit in using the WFS object is that it can be used by browsers and WebDAV clients. The only drawback with the WFS is that it triggers the execution of Lua code, thus slightly slowing down the operation when using WebDAV. You should use the DAV object if your objective is to create a very fast WebDAV server since the DAV object uses a pure "C" implementation and not a hybrid solution.

The Mako Server’s Virtual File System

The Virtual File System (VFS) makes it possible for you to programmatically build application server resources in a running system. The VFS is responsible for mapping URLs to resources such as your application's LSP pages. The Mako Server provides a number of pre-defined objects that can be created and installed into the VFS such as the WebDAV object. You can also define your own objects and insert these objects into the VFS.

It is common to create VFS nodes such as the WebDAV object at system startup in a ".preload" script. Your application's ".preload" script is run at startup and this script can create VFS nodes and populate the Mako Server's VFS. It is also possible to dynamically insert say a WebDAV object into the VFS from a Lua Server Page (LSP). The user would then first have to visit the LSP before the WebDAV object would be accessible. This would be inconvenient since the user would have to visit the LSP before the user could access the WebDAV resource.

The Lua Tutorials includes a number of examples that teaches you the VFS fundamentals. You can also read the VFS introduction in our online documentation.

WebDAV and Web-File-Server Virtual File System Nodes

You can find the two file server objects in the documentation. Here are the links to the online documentation:

DAV locking is a part of the WebDAV standard and we need to provide a directory for the DAV object for file lock operations. You can use the DAV object without a lock directory, but some WebDAV clients will be in "read only" mode when connecting to a DAV object that does not support file locking.

The following example shows how to create a lock directory using the Mako Server's root directory object:

local rio = ba.openio"disk" -- The root IO
local env = mako.env
local ldir = mako.dos2unix(env and (env.TMP or env.TEMP) or "/tmp").."/.LOCK"
if not rio:stat(ldir) then
   if not rio:mkdir(ldir) then
      trace("Cannot open WebDAV lock directory:",ldir)
      ldir=nil -- WebDAV may be in read only mode when used by some clients

Example 1: Shows how to create the WebDAV lock directory.

The above code tries to find the host systems TEMP directory from the system’s environment variables. It then uses the root IO when creating the .LOCK sub directory in the TEMP directory. The dos2unix function makes sure the code also works when run on Windows. The IO interface requires UNIX style paths on all operating systems. For example, a TEMP directory such as c:\TEMP is translated by dos2unix to the path /c/TEMP/. The Mako server provides a number of IO interfaces. See Mako Specific features for more information on the IO interfaces provided. You can also create your own custom IO interface that for example uses a database for storing files – in other words, you can have a WebDAV server that stores all resources in a database.

We can create the DAV object and insert it into the Virtual File System (VFS) as soon as we have a lock directory. The lock directory must be set to nil if you do not want to use a lock directory.

local maxUploads=50
local maxLocks=100
require"wfs" -- install ba.create.wfs by loading it from
fsdir:insert() -- Insert as a root node with name 'fs' in the VFS

Example 2: Shows how to create a WFS object and insert the object into the Virtual File System.

You can copy the above Lua scripts in example 1 and 2, paste it into a .preload script, and use the Mako Server to load the .preload script. You can then access the Web File Manager using a browser by navigating to the URL http://server-name/fs/.


Running the above code for anything but test purposes is not recommended since you have no security and anyone can access the Web File Manager and WebDAV server without having to log in. What’s missing from the above code is an authenticator and authorizer object. The following code installs a Digest authenticator object in the WFS object.

-- The username/password callback function.
local function getpassword(username)
   if username == "admin" then return "admin" end
-- Create the username database from our getpassword func.
local authuser=ba.create.authuser(getpassword)
-- Create authenticator by using the username database.
local authenticator=ba.create.authenticator(authuser)
-- Enable authentication for the directory.

Example 3: Installing a Digest Authentication object in the WFS object.

The above password function makes it possible to login with the username ‘admin’ and password ‘admin’. This function can easily be redesigned such that the function fetches the credentials from a SQL database.

Many WebDAV clients require Digest Authentication and this is also the default authenticator type created by function ba.create.authenticator. You may want to use form based authentication for browser users. The Barracuda Application Server provides many authentication types and you can make an authenticator object use form based authentication for browsers and Digest for WebDAV clients. Make sure you have a local copy of the Barracuda Application Server documentation and then read up on the various authenticator types.

In addition to providing authentication, it’s also common to provide an authorizer object for WebDAV objects. An authorizer object may limit the authenticated user’s access rights. Creating an authorizer object is explained in the documentation.

The WFS object in the BarracudaDrive server uses the JSON authenticator and the JSON authorizer, which provides a self contained mini user and constraint database system based on JSON. The JSON data can be saved to disk and reloaded at system start. You may want to study how the authenticator and authorizer code in BarracudaDrive works. This code is located in the .config script inside See the BarracudaDrive developer page for more information.

Download Example Code

Download example from GitHub

Discover More:

No matter what your background or project goals, we're here to help you find the perfect solution! Are you a maker looking for the right tools? A startup trying to get off the ground? A large business seeking new software solutions? We've got you covered.

If you have any questions or just aren't sure which product is right for you, don't hesitate to reach out. Our team is dedicated to helping you overcome your hardware/software challenges and find the best solution for your needs. Let us know how we can help - we'd love to lend a hand!


OPC-UA Client & Server

An easy to use OPC UA stack that enables bridging of OPC-UA enabled industrial products with cloud services, IT, and HTML5 user interfaces.

Edge Controller

Edge Controller

Use our user programmable Edge-Controller as a tool to accelerate development of the next generation industrial edge products and to facilitate rapid IoT and IIoT development.

On-Premises IoT

On-Premises IoT Platform

Learn how to use the Barracuda App Server as your On-Premises IoT Foundation.

Embedded Web Server

Barracuda Embedded Web Server

The compact Web Server C library is included in the Barracuda App Server protocol suite but can also be used standalone.

WebSocket Server

Microcontroller Friendly

The tiny Minnow Server enables modern web server user interfaces to be used as the graphical front end for tiny microcontrollers. Make sure to check out the reference design and the Minnow Server design guide.

WebDAV Server

Network File System

Why use FTP when you can use your device as a secure network drive.

HTTP Client

Secure HTTP Client Library

PikeHTTP is a compact and secure HTTP client C library that greatly simplifies the design of HTTP/REST style apps in C or C++.

WebSocket Client

Microcontroller Friendly

The embedded WebSocket C library lets developers design tiny and secure IoT applications based on the WebSocket protocol.

SMTP Client

Secure Embedded SMTP Library

Send alarms and other notifications from any microcontroller powered product.

Crypto Library

RayCrypto C Library

The RayCrypto engine is an extremely small and fast embedded crypto library designed specifically for embedded resource-constrained devices.

Embedded PKI Service

Automatic SSL Certificate Management for Devices

Real Time Logic's SharkTrust™ service is an automatic Public Key Infrastructure (PKI) solution for products containing an Embedded Web Server.


Modbus TCP client

The Modbus client enables bridging of Modbus enabled industrial products with modern IoT devices and HTML5 powered HMIs.

Posted in Tutorials by bd