Bot Tech

IRC, the Internet Relay Chat has existed for 20 years, and it is still a popular communication channel in open source projects and businesses. For almost as long, automated bots have listened on IRC channels and responded to user commands. The article shows how IRC bots can make themselves useful by helping you manage tickets and prepare documentation.

Spoiled for Choice

To develop an IRC bot today, you no longer need to learn Tcl to activate the bot ancestor Eggdrop [1]. Frameworks for bots are available in virtually any language (Table 1). Although I focus here on Cinch [2], a framework written in Ruby under the MIT license (Figure 1), you can easily adapt the code examples presented in this article to other languages.

Figure 1: The simplified structure of the Cinch Ruby bot.

Cinch comes with an object-oriented API and a modular plugin system. Thanks to many unrelated plugins, a single bot can perform all kinds of tasks. To an IRC server, Cinch – as is typical of IRC bots – appears as a normal client. Therefore, it does not matter which system the bot runs on, whether on the same system as the IRC server or remotely on a developer machine. Nor does it matter which server software you use, as long as the server is a compliant implementation of IRC.

Bot on Board

Assuming you have a Ruby installation in place, you can install Cinch as follows:

gem install cinch

A simple bot named hellobot.rb (Figure 2) that responds to salutations in the form of !hello is presented in Listing 1.

Figure 2: A perpetual responder in its simplest form.

Typing ruby hellobot.rb brings the bot to life; it then connects with the IRC server <IRC_server_address> and joins the channels <#a_channel> and <#another_channel>. If an IRC user types !hello in one of these channels, the bot responds with a rather indifferent Hi there.

The sample code consists of two parts: The main part is the Greeter class (lines 4-11). Each class represents a single plugin that responds to one or more commands from the user; a command must begin with an exclamation mark. To match the commands, bot developers rely on regular expressions. For example, /(\d+)/ is a single argument comprising one or multiple numbers.

The second part (lines 13-20) takes care of configuring the bot. The program receives a name and an address at which it can log in. Line 18 also explains what plugins the bot should use. The configuration of the file does not change in the remainder of the article, so I can now move on to the actual plugin classes. Developers can easily extend the array of plugins; for more information on the API, check out the documentation [3].

GitHub Connection

Developers spend a huge amount of time processing tickets; little wonder their conversations often revolve around this topic. This article will show you how to build a bot that will control the GitHub ticket system. A plugin will support opening, closing, and finding tickets. At the same time, I want the bot to respond to references of the type repository/gh-ticket_number in messages by displaying the title status of the ticket in the channel.

GitHub's API [4] is based on HTTP and JSON and allows both read and write access to large parts of GitHub – including tickets. You can experiment with access using curl at the command line; Listing 2, for example, requests ticket number 13069 from the Rails project.

This (abridged) example shows how GitHub structures the information the bot requires to display tickets. The developer can access both public information (such as tickets from open source projects) as well as private tickets [5]. In the second case, however, you do need to authenticate. The API allows authentication either via O-Auth or classic HTTP, which is usually sufficient for an IRC bot. For in-house installations of GitHub, access to the API looks like this: http://<IP_address>/api/v3/.