Using Limnoria’s HTTP server in your plugins

Introduction

Note

Until stock Supybot or Gribble merge the HTTP server, this documentation only applies to Limnoria.

Limnoria provides an HTTP server to plugins. This is not relevant for most plugins, but some of them have to start a server (either for serving a website or for being remotely called). The HTTP server provided by Limnoria aims at starting a single server for all of them, which means less used port and less resources usage.

Some example plugins are Factoids, WebStats, GitHub, UfrPaste, and WebDoc

Using the HTTP server in a plugin

Let’s try to make a basic dictionary about Supybot! We’ll call it Supystory.

We want to get plain text information about Supybot, Gribble, and Limnoria when accessing http://localhost:8080/supystory/supybot, http://localhost:8080/supystory/gribble, and http://localhost:8080/supystory/limnoria, an index page, and an HTML error page if the page is not found

Importing the HTTP server

On only have to add this line:

from supybot import httpserver

Creating a callback

If you are familiar with BaseHTTPServer, you will recognize the design, except you don’t need to subclass BaseHTTPServer, because I already did it in supybot.httpserver.

Now, you have to subclass httpserver.SupyHTTPServerCallback. A callback is pretty much like an handler, but this is not an handler, because a callback is called by the handler.

Here is how to do it:

class SupystoryServerCallback(httpserver.SupyHTTPServerCallback):
    name = 'Supystory'

Now, you have to register the callback, because the HTTP server does not know what subdirectory it should assign to your callback. Do it with adding a __init__ to your plugin (read Supybot’s docs about it, for more informations):

class Supystory(callbacks.Plugin):
    def __init__(self, irc):
        # Some stuff needed by Supybot
        super().__init__(irc)

        # registering the callback
        callback = SupystoryServerCallback() # create an instance of the callback
        httpserver.hook('supystory', callback) # register the callback at `/supystory`

By the way, don’t forget to unhook your callback when unloading your plugin, unless what it will be impossible to reload the plugin! Append this code to the following:

def die(self):
    # unregister the callback
    httpserver.unhook('supystory') # unregister the callback hooked at /supystory

    # Stuff for Supybot
    super().die()

Now, you can load your plugin, and you’ll see on the server a beautiful link to /supystory called Supystory.

Overriding the default error message

But our plugin does not do anything for the moment. If click the link, you’ll get this message:

This is a default response of the Supybot HTTP server. If you see this
message, it probably means you are developping a plugin, and you have
neither overriden this message or defined an handler for this query.

That mean your browser sent a GET request, but you didn’t teach your plugin how to handle it. First, we’ll change this error message. Here is a new code for your callback:

class SupystoryServerCallback(httpserver.SupyHTTPServerCallback):
    name = 'Supystory'
    defaultResponse = """
    This plugin handles only GET request, please don't use other requests."""

Now, you’ll get your customized message. But your plugin still doesn’t work. You need to implement the GET request.

Implementing the GET request

As I said before, callbacks are pretty much like handlers. In order to handle GET requests, you have to implement a method called… doGet (if you used BaseHTTPServer, you will notice this is not do_GET, because doGet is more homogeneous with Supybot naming style: doPrivmsg, doPing, and so on).

You will get the handler and the URI as arguments. The handler is a BaseHTTPRequestHandler, and the URI is a string.

Here is the code of the callback… pretty much simple, as ever:

class SupystoryServerCallback(httpserver.SupyHTTPServerCallback):
    name = 'Supystory'
    defaultResponse = """
    This plugin handles only GET request, please don't use other requests."""

    def doGet(self, handler, path):
        if path == '/supybot':
             response = b'Supybot is the best IRC bot ever.'
        elif path == '/gribble':
             response = b'Thanks to Gribble, we have many bug fixes and SQLite 3 support'
        elif path == '/limnoria':
             response = b'Thanks to Limnoria, you can to internationalize your plugins and write a web server.'
        elif path == '' or path == '/':
             handler.send_response(200) # Found
             handler.send_header('Content-type', 'text/html') # This is the MIME for HTML data
             handler.end_headers() # We won't send more headers
             handler.wfile.write(b"""
             <!DOCTYPE html>
             <html>
              <head>
               <meta charset="UTF-8">
               <title>Supystory</title>
              </head>
              <body>
               <h1>Supystory</h1>
               <p>
                Here are some links you can visit:
                <a href="./supybot">Supybot</a>
                <a href="./gribble">Gribble</a>
                <a href="./limnoria">Limnoria</a>
               </p>
              </body>
             </html>""")
             return
        else:
             handler.send_response(404) # Not found
             handler.send_header('Content-type', 'text/html') # This is the MIME for HTML data
             handler.end_headers() # We won't send more headers
             handler.wfile.write(b"""
             <!DOCTYPE html>
             <html>
              <head>
               <meta charset="UTF-8">
               <title>Error</title>
              </head>
              <body>
               <h1>404 Not found</h1>
               <p>
                The document could not be found. Try one of this links:
                <a href="./supybot">Supybot</a>
                <a href="./gribble">Gribble</a>
                <a href="./limnoria">Limnoria</a>
               </p>
              </body>
             </html>""")
             return
        handler.send_response(200)
        handler.send_header('Content-type', 'text/plain') # This is the MIME for plain text
        handler.end_headers() # We won't send more headers
        handler.wfile.write(response)

Using templates

You may also want to allow your plugin’s users to customize the web pages without editing the source code of the plugin itself.

Limnoria provides a template facility, which takes a file name, returns the content of a file from the file system if it exists (the user-defined template), and a default one otherwise (the developer’s default template). does not exist.

In our case, we will do it only for the home page and the error page (which are the only ‘big’ pages), like this:

DEFAULT_TEMPLATES = {
    'supystory/index.html': """
<!DOCTYPE html>
<html>
    <head>
        <meta charset="UTF-8">
        <title>Supystory</title>
    </head>
    <body>
        <h1>Supystory</h1>
        <p>
            Here are some links you can visit:
            <a href="./supybot">Supybot</a>
            <a href="./gribble">Gribble</a>
            <a href="./limnoria">Limnoria</a>
        </p>
    </body>
</html>""",
    'supystory/error.html': """
<!DOCTYPE html>
<html>
    <head>
        <meta charset="UTF-8">
        <title>Error</title>
    </head>
    <body>
        <h1>404 Not found</h1>
        <p>
            The document could not be found. Try one of this links:
            <a href="./supybot">Supybot</a>
            <a href="./gribble">Gribble</a>
            <a href="./limnoria">Limnoria</a>
        </p>
    </body>
</html>"""
}

httpserver.set_default_templates(DEFAULT_TEMPLATES)



class SupystoryServerCallback(httpserver.SupyHTTPServerCallback):
    name = 'Supystory'
    defaultResponse = """
    This plugin handles only GET request, please don't use other requests."""

    def doGet(self, handler, path):
        if path == '/supybot':
             response = b'Supybot is the best IRC bot ever.'
        elif path == '/gribble':
             response = b'Thanks to Gribble, we have many bug fixes and SQLite 3 support'
        elif path == '/limnoria':
             response = b'Thanks to Limnoria, you can to internationalize your plugins and write a web server.'
        elif path == '' or path == '/':
             handler.send_response(200) # Found
             handler.send_header('Content-type', 'text/html') # This is the MIME for HTML data
             handler.end_headers() # We won't send more headers
             handler.wfile.write(httpserver.get_template('supystory/index.html').encode('utf8'))
             return
        else:
             handler.send_response(404) # Not found
             handler.send_header('Content-type', 'text/html') # This is the MIME for HTML data
             handler.end_headers() # We won't send more headers
             handler.wfile.write(httpserver.get_template('supystory/error.html').encode('utf8'))
             return
        handler.send_response(200)
        handler.send_header('Content-type', 'text/plain') # This is the MIME for plain text
        handler.end_headers() # We won't send more headers
        handler.wfile.write(response)

Then, the user can change the template by copying data/web/supystory/index.html.example to data/web/supystory/index.html and editing it. (Same for error.html.)