Friday, July 19, 2013

Be careful what you ask for (or at least don't let yourself be inoculated when you get it)

Since the verdict in the Trayvon Martin case came down on July 13th there has been an outcry of "injustice!" in my infosphere.  I generally agree with the conclusions made in this piece, but I have found the outcry to be hollow.

Do this thought exercise...  Think of America on July 12th before the jury handed out the verdict.  Now imagine a guilty verdict for George Zimmerman (on all counts if you prefer or perhaps just the manslaughter count).  Then imagine American now; now that "justice has been served."  Would the present outcry over injustice still exist?  And would we would be better or worse off?

Justice is never only about one person or family.  Justice is systemic and surrounds and impacts all of us whether we are conscious of it or not.  There is good reason to believe that we have systemic issues of justice to work on in America.  Perhaps the greatest gift that the Trayvon Martin jury gave us and the greatest legacy of the tragedy of Trayvon Martin is that we weren't given a piece of local justice at the expense of a more lasting and global justice.

Wednesday, July 17, 2013

Fast exception notification in rails

There are several highly regarded hosted exception notification and paging services services for rails apps such as Exceptional, AirbrakeBugsnag, PagerDuty but all of those cost $10-30/mo and with the exception of Bugsnag none of them have a free tier (note all of them have free trials).  So if you're starting a new web app and you intend to operate it like a pro, i.e. you want to be woken up in the middle of the night when something goes wrong you've got some work to do...  But it's not very much.  In this post you'll see how to integrate Amazon's Simple Notification service with the exception_notification gem.


  1. You've got a Rails 3 app...
  2. Running on AWS...
  3. And you have a mobile phone that supports text messages
First install and setup the exception_notification gem as documented on their github page.  In a nutshell.  Add "gem 'exception_notification'" to your Gemfile and run "bundle install"

Next lets setup a new Simple Notification Service topic and subscribe our mobile phone to it (full SNS documentation).

Create the topic:

Topic details without a subscription:

Create a subscription for our mobile phone:

A confirmation is bounced to our phone:

Confirm from our phone:

Topic and subscription are setup and ready to use:
Next you should grab the aws-sdk for Ruby and follow the installation instructions.  In a nutshell...  A "gem 'aws-sdk'" to your Gemfile.  Run "bundle install".  Create an aws.yml with your access key ID, and secret access key.  Create an initializer that pulls the aws.yml in to your app and sets up various AWS clients.  Assuming you've done that lets create our SNS notifier and configure our app to use it on exceptions.

In config/environments/production.rb add this code:
  config.middleware.use ExceptionNotification::Rack, :sns => {:topic_name => 'test-topic'}

Create lib/exception_notifier/sns_notifier.rb:

module ExceptionNotifier
  class SnsNotifier   
    attr_accessor :topic
    def initialize(options)
        @topic = SNS_CLIENT.topics.detect {|t| == options[:topic_name]}
    def call(exception, options={})
      @topic.publish("#{}: '#{exception.message}' at '#{exception.backtrace.first}'") if active?
    def active?
That's it.  Except of course to add an exception into your app and watch the notification on your phone:


Monday, July 15, 2013

An investigation of fruit with regard to it's ripeness..

I think about this plot every time I attempt to eat a slightly unripe avocado:

For a comparison of tastiness to difficulty consult the brilliant XKCD.