Exception Notifier Plugin for Rails

The Exception Notifier plugin provides a mailer object and a default set of templates for sending email notifications when errors occur in a Rails application.

The email includes information about the current request, session, and environment, and also gives a backtrace of the exception.

There's a great Railscast about Exception Notifications you can see that may help you getting started.

Installation

You can use the latest ExceptionNotification gem with Rails 3, by adding the following line in your Gemfile

gem 'exception_notification'

As of Rails 3 ExceptionNotification is used as a rack middleware, so you can configure its options on your config.ru file, or in the environment you want it to run. In most cases you would want ExceptionNotification to run on production. You can make it work by

Whatever::Application.config.middleware.use ExceptionNotifier,
  :email_prefix => "[Whatever] ",
  :sender_address => %{"notifier" <notifier@example.com>},
  :exception_recipients => %w{exceptions@example.com}

Customization

Sections

By default, the notification email includes four parts: request, session, environment, and backtrace (in that order). You can customize how each of those sections are rendered by placing a partial named for that part in your app/views/exception_notifier directory (e.g., _session.rhtml). Each partial has access to the following variables:

@controller     # the controller that caused the error
@request        # the current request object
@exception      # the exception that was raised
@backtrace      # a sanitized version of the exception's backtrace
@data           # a hash of optional data values that were passed to the notifier
@sections       # the array of sections to include in the email

Background views will not have access to @controller and @request.

You can reorder the sections, or exclude sections completely, by altering the ExceptionNotifier.sections variable. You can even add new sections that describe application-specific data--just add the section's name to the list (wherever you'd like), and define the corresponding partial.

#Example with two new added sections
Whatever::Application.config.middleware.use ExceptionNotifier,
 :email_prefix => "[Whatever] ",
 :sender_address => %{"notifier" <notifier@example.com>},
 :exception_recipients => %w{exceptions@example.com},
 :sections => %w{my_section1 my_section2} + ExceptionNotifier::Notifier.default_sections

If your new section requires information that isn't available by default, make sure it is made available to the email using the exception_data macro:

class ApplicationController < ActionController::Base
  before_filter :log_additional_data
  ...
  protected
    def log_additional_data
      request.env["exception_notifier.exception_data"] = {
        :document => @document,
        :person => @person
      }
    end
  ...
end

In the above case, @document and @person would be made available to the email renderer, allowing your new section(s) to access and display them. See the existing sections defined by the plugin for examples of how to write your own.

You may want to include different sections for background notifications:

#Example with two new added sections
Whatever::Application.config.middleware.use ExceptionNotifier,
 :email_prefix => "[Whatever] ",
 :sender_address => %{"notifier" <notifier@example.com>},
 :exception_recipients => %w{exceptions@example.com},
 :background_sections => %w{my_section1 my_section2} + ExceptionNotifier::Notifier.default_background_sections

By default, the backtrace and data sections are included in background notifications.

Ignore Exceptions

You can choose to ignore certain exceptions, which will make ExceptionNotifier avoid sending notifications for those specified. There are three ways of specifying which exceptions to ignore:

:ignore_exceptions - By exception class (i.e. ignore RecordNotFound ones)
:ignore_crawlers - From crawler (i.e. ignore ones originated by Googlebot)
:ignore_if - Custom (i.e. ignore exceptions that satisfy some condition)

:ignore_exceptions

Ignore specified exception types. To achieve that, you should use the :ignore_exceptions option, like this:

Whatever::Application.config.middleware.use ExceptionNotifier,
  :email_prefix         => "[Whatever] ",
  :sender_address       => %{"notifier" <notifier@example.com>},
  :exception_recipients => %w{exceptions@example.com},
  :ignore_exceptions    => ['ActionView::TemplateError'] + ExceptionNotifier.default_ignore_exceptions

The above will make ExceptionNotifier ignore a TemplateError exception, plus the ones ignored by default. By default, ExceptionNotifier ignores ActiveRecord::RecordNotFound, AbstractController::ActionNotFound and ActionController::RountingError.

:ignore_crawlers

In some cases you may want to avoid getting notifications from exceptions made by crawlers. Using :ignore_crawlers option like this,

Whatever::Application.config.middleware.use ExceptionNotifier,
  :email_prefix         => "[Whatever] ",
  :sender_address       => %{"notifier" <notifier@example.com>},
  :exception_recipients => %w{exceptions@example.com},
  :ignore_crawlers      => %w{Googlebot bingbot}

will prevent sending those unwanted notifications.

:ignore_if

Last but not least, you can ignore exceptions based on a condition, by

Whatever::Application.config.middleware.use ExceptionNotifier,
  :email_prefix         => "[Whatever] ",
  :sender_address       => %{"notifier" <notifier@example.com>},
  :exception_recipients => %w{exceptions@example.com},
  :ignore_if            => lambda { |env, e| e.message =~ /^Couldn't find Page with ID=/ }

You can make use of both the environment and the exception inside the lambda to decide wether to avoid or not sending the notification.

Verbose

You can also choose to exclude the exception message from the subject, which is included by default. Use :verbose_subject => false to exclude it.

Normalize subject

You can also choose to remove numbers from subject so they thread as a single one. This is disabled by default. Use :normalize_subject => true to enable it.

HTML

You may want to send multipart notifications instead of just plain text, which ExceptionNotification sends by default. You can do so by adding this to the configuration: :email_format => :html.

Background Notifications

If you want to send notifications from a background process like DelayedJob, you should use the background_exception_notification method like this:

begin
  some code...
rescue => e
  ExceptionNotifier::Notifier.background_exception_notification(e)
end

You can include information about the background process that created the error by including a data parameter:

begin
  some code...
rescue => exception
  ExceptionNotifier::Notifier.background_exception_notification(exception,
    :data => {:worker => worker.to_s, :queue => queue, :payload => payload})
end

Manually notify of exception

If your controller action manually handles an error, the notifier will never be run. To manually notify of an error you can do something like the following:

rescue_from Exception, :with => :server_error

def server_error(exception)
  # Whatever code that handles the exception

  ExceptionNotifier::Notifier.exception_notification(request.env, exception,
    :data => {:message => "was doing something wrong"}).deliver
end