Hedwig
An Adapter-based Bot Framework for Elixir Applications
Hedwig is a chat bot, highly inspired by GitHub's Hubot.
See the online documentation for more information.
Hedwig was designed for 2 use-cases:
- A single, stand-alone OTP application.
- Included as a dependency of other OTP applications (or an umbrella).
You can spawn multiple bots at run-time with different configurations.
Adapters
Check out enilsen16/awesome-hedwig for a curated list of adapters, responders, and other resources.
Getting started
Hedwig ships with a console adapter to get you up and running quickly. It'sgreat for testing how your bot will respond to the messages it receives.
To add Hedwig to an existing Elixir application, add :hedwig to your list ofdependencies in your mix.exs file:
defp deps do
[{:hedwig, "~> 1.0"}]
end
Update your applications list to include :hedwig. This will ensure that theHedwig application, along with it's supervision tree is started when you startyour application.
def applications do
[applications: [:hedwig]]
end
Fetch the dependencies:
$ mix deps.get
Create a robot module
Hedwig provides a convenient mix task to help you generate a basic robot module.
Run the following and follow the prompts:
$ mix hedwig.gen.robot
Welcome to the Hedwig Robot Generator!
Let's get started.
What would you like to name your bot?: alfred
Available adapters
1. Hedwig.Adapters.Console
Please select an adapter: 1
* creating lib/alfred
* creating lib/alfred/robot.ex
* updating config/config.exs
Don't forget to add your new robot to your supervision tree
(typically in lib/alfred.ex):
worker(Alfred.Robot, [])
defmodule Alfred.Robot do
use Hedwig.Robot, otp_app: :alfred
...
end
Configuration
The generator will automatically generate a default configuration inconfig/config.exs. You will need to customize it further depending on theadapter you will use.
This is mainly to setup the module to be compiled along with the adapter. Anadapter can inject functionality into your module if needed.
# config/config.exs
config :alfred, Alfred.Robot,
adapter: Hedwig.Adapters.Console,
name: "alfred",
aka: "/",
responders: [
{Hedwig.Responders.Help, []},
{Hedwig.Responders.Ping, []}
]
Start a bot.
You can start your bot as part of your application's supervision tree or byusing the supervision tree provided by Hedwig.
Starting as part of your supervision tree:
# add this to the list of your supervisor's children
worker(Alfred.Robot, [])
Trying out the console adapter:
mix run --no-halt
Hedwig Console - press Ctrl+C to exit.
The console adapter is useful for quickly verifying how your
bot will respond based on the current installed responders.
scrogson> alfred help
alfred> alfred help <query> - Displays all help commands that match <query>.
alfred help - Displays all of the help commands that alfred knows about.
alfred: ping - Responds with 'pong'
scrogson>
Starting bots manually:
# Start the bot via the module. The configuration options will be read in from
# config.exs
{:ok, pid} = Hedwig.start_robot(Alfred.Robot)
# You can also pass in a list of options that will override the configuration
# provided in config.exs (except for the adapter as that is compiled into the
# module).
{:ok, pid} = Hedwig.start_robot(Alfred.Robot, [name: "jeeves"])
Registering your robot process
If you want to start, stop, and send messages to your bot without keeping trackof its pid, you can register your robot in the handle_connect/1 callback inyour robot module like so:
defmodule Alfred.Robot do
use Hedwig.Robot, otp_app: :alfred
def handle_connect(%{name: name} = state) do
if :undefined == :global.whereis_name(name) do
:yes = :global.register_name(name, self())
end
{:ok, state}
end
end
Process registration via Process.register/2 is simple. However, since the namecan only be an atom it may not work for all use-cases. If you are using the samemodule for many robots, you'll need to reach for something more flexible like:
Finding your robot
# Start the robot
Hedwig.start_robot(Alfred.Robot)
# Get the pid of the robot by name
pid = :global.whereis_name("alfred")
# Start a new robot with a different name
Hedwig.start_robot(Alfred.Robot, [name: "jeeves"])
# Get the pid
pid = :global.whereis_name("jeeves")
# Stop the robot
Hedwig.stop_robot(pid)
Sending Messages
# Get the pid of the robot
pid = :global.whereis_name("alfred")
# Create a Hedwig message
msg = %Hedwig.Message{
type: "groupchat",
room: "my_room@example.com",
text: "hello world"
}
# Send the message
Hedwig.Robot.send(pid, msg)
Building Responders
Responders are processes that will handle incoming messages.
All that's needed is to use Hedwig.Responder and use the hear/2, orrespond/2 macros to define a pattern to listen for and how to respond inthe block when a message matches.
Here is an example:
defmodule MyApp.Responders.GreatSuccess do
@moduledoc """
Borat, Great Success!
Replies with a random link to a Borat image when a message contains
'great success'.
"""
use Hedwig.Responder
@links [
"http://mjanja.co.ke/wordpress/wp-content/uploads/2013/09/borat_great_success.jpg",
"http://s2.quickmeme.com/img/13/1324dfd733535e58dba70264e6d05c9b70346204d2cacef65abef9c702746d1c.jpg",
"https://www.youtube.com/watch?v=r13riaRKGo0"
]
@usage """
<text> (great success) - Replies with a random Borat image.
"""
hear ~r/great success(!)?/i, msg do
reply msg, random(@links)
end
end
Hear vs. Respond
The two responder macros are use for different reasons:
hear- matches messages containing the regular expressionrespond- matches only when prefixed by your robot's configurednameorakavalue.
Testing responders:
Hedwig ships with a ExUnit-based module sepecifically made to test responders: Hedwig.RobotCase.
In order to test the above responder, you need to create an ExUnit test case:
# test/my_app/responders/great_success_test.exs
defmodule MyApp.Responders.GreatSuccessTest do
use Hedwig.RobotCase
@tag start_robot: true, name: "alfred", responders: [{MyApp.Responders.GreatSuccess, []}]
test "great success - responds with a borat url", %{adapter: adapter, msg: msg} do
send adapter, {:message, %{msg | text: "great success"}}
assert_receive {:message, %{text: text}}
assert String.contains?(text, "http")
end
end
To run the tests, use mix test
@usage
The @usage module attribute works nicely with Hedwig.Responders.Help. If youinstall the help handler, your bot will listen for <your-bots-nickname> helpand respond with a message containing all of the installed handlers @usagetext.
License
The MIT License (MIT)
Copyright (c) 2015 Sonny Scroggin
Permission is hereby granted, free of charge, to any person obtaining a copyof this software and associated documentation files (the "Software"), to dealin the Software without restriction, including without limitation the rightsto use, copy, modify, merge, publish, distribute, sublicense, and/or sellcopies of the Software, and to permit persons to whom the Software isfurnished to do so, subject to the following conditions:
The above copyright notice and this permission notice shall be included in allcopies or substantial portions of the Software.
THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS ORIMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THEAUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHERLIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THESOFTWARE.