#What

DSL - A domain specific language, where code is written in one language and errors are given in another. --The Devil's Dictionary of Programming

Grappling is a tiny, hacky DSL for inflatable Webhooks for Ruby and PagerDuty. It uses Sinatra, Resque, and Bootstrap. Bring your own Redis install, or just get a free one from redis to go.

It is pretty OK for quick prototypes, one-off servers, and PagerDuty's hack days.

#Install

gem install grappling

#Example

# example.rb
require 'grappling'

redis_url "redis://redistogo:password@whatever.redistogo.com:12345/"
name "Grappling Example"

grapple do
    if is_trigger?
      # do something interesting here
    end
end

Then just run

grapple go example.rb

to start a webserver, and

grapple do example.rb

To run a queue worker

##The Worker

###is_trigger?, is_acknowledge?, is_resolve?, is_unacknowledge?, is_assign?, is_escalate?, is_delegate?

Predicates of the message that let you know the trigger type.

###description

The message's description

###user

user is a hash that contains stuff related to the assigned_to (or, as appropriate the resolved_by). :email and :name are two useful fields in this hash.

###message

A hash version of the Webhook message sent by PagerDuty.

##Helper and Configuration Methods ###redis_url

redis_url configures the URL where Redis is set up, along with authentication details. e.g. redis://username:password@host:port/. The username is ignored because Redis doesn't support usernames.

###name

The application's name. It's important and should be unique on the redis url you use.

#Heroku

Setting up a Grappling application on Heroku is super easy. Mostly, you just follow these notes. Notable differences:

You need gem 'grappling', not gem 'sinatra' in your Gemfile.

Add set port, ENV["PORT"] to your application file.

Your Procfile should look like:

web: bundle exec grapple go my_application.rb
worker: bundle exec grapple do my_application.rb

#Other Random Notes

##JSON Handling

PagerDuty collapses a bunch of events into a single Webhook call. We split them back out and make a task for each message.

##To rebuild the gem

gem build grappling.gemspec
gem install grappling-[version].gem

##Use ssh port forwarding to expose your development endpoint

For hack days, this is how I prefer to work instead of actually hosting this somewhere. This sets up a tunnel so host:8888 forwards to localhost:4567

ssh -R *:8888:localhost:4567 username@host

##Change the default port

In development mode, Grappling runs on port 4567 (this is just Sinatra after all). You can change this, or any other Sinatra option, as follows:

set :port, 80