Implementing ExceptionNotifier

Author: Tom Copeland

app/controllers/application_controller.rb

@@ -6,6 +6,8 @@ class ApplicationController < ActionController::Base
   before_filter :require_logged_in, :require_not_overeager
   around_filter :record_api_request
 
+  include ExceptionNotifiable
+
   def current_user
     @current_user ||= authenticate_or_request_with_http_basic("RubyForge API") do |username, password|
       User.authenticate(username, password)

config/environment.rb

@@ -42,3 +42,6 @@
 require 'digest/md5'
 
 require 'pp'
+
+ExceptionNotifier.exception_recipients = %w(tom@infoether.com)
+ExceptionNotifier.sender_address = %("RubyForge API Error" <noreply@rubyforge.org>)

vendor/plugins/exception_notification/README

@@ -0,0 +1,111 @@
+= 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 plugin is configurable, allowing programmers to specify:
+
+* the sender address of the email
+* the recipient addresses
+* the text used to prefix the subject line
+
+The email includes information about the current request, session, and
+environment, and also gives a backtrace of the exception.
+
+== Usage
+
+First, include the ExceptionNotifiable mixin in whichever controller you want
+to generate error emails (typically ApplicationController):
+
+  class ApplicationController < ActionController::Base
+    include ExceptionNotifiable
+    ...
+  end
+
+Then, specify the email recipients in your environment:
+
+  ExceptionNotifier.exception_recipients = %w(joe@schmoe.com bill@schmoe.com)
+
+And that's it! The defaults take care of the rest.
+
+== Configuration
+
+You can tweak other values to your liking, as well. In your environment file,
+just set any or all of the following values:
+
+  # defaults to exception.notifier@default.com
+  ExceptionNotifier.sender_address =
+    %("Application Error" <app.error@myapp.com>)
+
+  # defaults to "[ERROR] "
+  ExceptionNotifier.email_prefix = "[APP] "
+
+Email notifications will only occur when the IP address is determined not to
+be local. You can specify certain addresses to always be local so that you'll
+get a detailed error instead of the generic error page. You do this in your
+controller (or even per-controller):
+
+  consider_local "64.72.18.143", "14.17.21.25"
+
+You can specify subnet masks as well, so that all matching addresses are
+considered local:
+
+  consider_local "64.72.18.143/24"
+
+The address "127.0.0.1" is always considered local. If you want to completely
+reset the list of all addresses (for instance, if you wanted "127.0.0.1" to
+NOT be considered local), you can simply do, somewhere in your controller:
+
+  local_addresses.clear
+
+== Customization
+
+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
+* @host: the name of the host that made the request
+* @backtrace: a sanitized version of the exception's backtrace
+* @rails_root: a sanitized version of RAILS_ROOT
+* @data: a hash of optional data values that were passed to the notifier
+* @sections: the array of sections to include in the email
+
+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
+(whereever you'd like), and define the corresponding partial. Then, 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
+    ...
+    protected
+      exception_data :additional_data
+
+      def additional_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.
+
+== Advanced Customization
+
+By default, the email notifier will only notify on critical errors. For
+ActiveRecord::RecordNotFound and ActionController::UnknownAction, it will
+simply render the contents of your public/404.html file. Other exceptions
+will render public/500.html and will send the email notification. If you want
+to use different rules for the notification, you will need to implement your
+own rescue_action_in_public method. You can look at the default implementation
+in ExceptionNotifiable for an example of how to go about that.
+
+
+Copyright (c) 2005 Jamis Buck, released under the MIT license

vendor/plugins/exception_notification/init.rb

@@ -0,0 +1,4 @@
+require "action_mailer"
+require "exception_notifier"
+require "exception_notifiable"
+require "exception_notifier_helper"

vendor/plugins/exception_notification/lib/exception_notifiable.rb

@@ -0,0 +1,99 @@
+require 'ipaddr'
+
+# Copyright (c) 2005 Jamis Buck
+#
+# Permission is hereby granted, free of charge, to any person obtaining
+# a copy of this software and associated documentation files (the
+# "Software"), to deal in the Software without restriction, including
+# without limitation the rights to use, copy, modify, merge, publish,
+# distribute, sublicense, and/or sell copies of the Software, and to
+# permit persons to whom the Software is furnished to do so, subject to
+# the following conditions:
+#
+# The above copyright notice and this permission notice shall be
+# included in all copies or substantial portions of the Software.
+#
+# THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
+# EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
+# MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
+# NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
+# LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, 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 THE SOFTWARE.
+module ExceptionNotifiable
+  def self.included(target)
+    target.extend(ClassMethods)
+  end
+
+  module ClassMethods
+    def consider_local(*args)
+      local_addresses.concat(args.flatten.map { |a| IPAddr.new(a) })
+    end
+
+    def local_addresses
+      addresses = read_inheritable_attribute(:local_addresses)
+      unless addresses
+        addresses = [IPAddr.new("127.0.0.1")]
+        write_inheritable_attribute(:local_addresses, addresses)
+      end
+      addresses
+    end
+
+    def exception_data(deliverer=self)
+      if deliverer == self
+        read_inheritable_attribute(:exception_data)
+      else
+        write_inheritable_attribute(:exception_data, deliverer)
+      end
+    end
+
+    def exceptions_to_treat_as_404
+      exceptions = [ActiveRecord::RecordNotFound,
+                    ActionController::UnknownController,
+                    ActionController::UnknownAction]
+      exceptions << ActionController::RoutingError if ActionController.const_defined?(:RoutingError)
+      exceptions
+    end
+  end
+
+  private
+
+    def local_request?
+      remote = IPAddr.new(request.remote_ip)
+      !self.class.local_addresses.detect { |addr| addr.include?(remote) }.nil?
+    end
+
+    def render_404
+      respond_to do |type|
+        type.html { render :file => "#{RAILS_ROOT}/public/404.html", :status => "404 Not Found" }
+        type.all  { render :nothing => true, :status => "404 Not Found" }
+      end
+    end
+
+    def render_500
+      respond_to do |type|
+        type.html { render :file => "#{RAILS_ROOT}/public/500.html", :status => "500 Error" }
+        type.all  { render :nothing => true, :status => "500 Error" }
+      end
+    end
+
+    def rescue_action_in_public(exception)
+      case exception
+        when *self.class.exceptions_to_treat_as_404
+          render_404
+
+        else          
+          render_500
+
+          deliverer = self.class.exception_data
+          data = case deliverer
+            when nil then {}
+            when Symbol then send(deliverer)
+            when Proc then deliverer.call(self)
+          end
+
+          ExceptionNotifier.deliver_exception_notification(exception, self,
+            request, data)
+      end
+    end
+end

vendor/plugins/exception_notification/lib/exception_notifier.rb

@@ -0,0 +1,66 @@
+require 'pathname'
+
+# Copyright (c) 2005 Jamis Buck
+#
+# Permission is hereby granted, free of charge, to any person obtaining
+# a copy of this software and associated documentation files (the
+# "Software"), to deal in the Software without restriction, including
+# without limitation the rights to use, copy, modify, merge, publish,
+# distribute, sublicense, and/or sell copies of the Software, and to
+# permit persons to whom the Software is furnished to do so, subject to
+# the following conditions:
+#
+# The above copyright notice and this permission notice shall be
+# included in all copies or substantial portions of the Software.
+#
+# THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
+# EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
+# MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
+# NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
+# LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, 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 THE SOFTWARE.
+class ExceptionNotifier < ActionMailer::Base
+  @@sender_address = %("Exception Notifier" <exception.notifier@default.com>)
+  cattr_accessor :sender_address
+
+  @@exception_recipients = []
+  cattr_accessor :exception_recipients
+
+  @@email_prefix = "[ERROR] "
+  cattr_accessor :email_prefix
+
+  @@sections = %w(request session environment backtrace)
+  cattr_accessor :sections
+
+  self.template_root = "#{File.dirname(__FILE__)}/../views"
+
+  def self.reloadable?() false end
+
+  def exception_notification(exception, controller, request, data={})
+    content_type "text/plain"
+
+    subject    "#{email_prefix}#{controller.controller_name}##{controller.action_name} (#{exception.class}) #{exception.message.inspect}"
+
+    recipients exception_recipients
+    from       sender_address
+
+    body       data.merge({ :controller => controller, :request => request,
+                  :exception => exception, :host => (request.env["HTTP_X_FORWARDED_HOST"] || request.env["HTTP_HOST"]),
+                  :backtrace => sanitize_backtrace(exception.backtrace),
+                  :rails_root => rails_root, :data => data,
+                  :sections => sections })
+  end
+
+  private
+
+    def sanitize_backtrace(trace)
+      re = Regexp.new(/^#{Regexp.escape(rails_root)}/)
+      trace.map { |line| Pathname.new(line.gsub(re, "[RAILS_ROOT]")).cleanpath.to_s }
+    end
+
+    def rails_root
+      @rails_root ||= Pathname.new(RAILS_ROOT).cleanpath.to_s
+    end
+
+end

vendor/plugins/exception_notification/lib/exception_notifier_helper.rb

@@ -0,0 +1,78 @@
+require 'pp'
+
+# Copyright (c) 2005 Jamis Buck
+#
+# Permission is hereby granted, free of charge, to any person obtaining
+# a copy of this software and associated documentation files (the
+# "Software"), to deal in the Software without restriction, including
+# without limitation the rights to use, copy, modify, merge, publish,
+# distribute, sublicense, and/or sell copies of the Software, and to
+# permit persons to whom the Software is furnished to do so, subject to
+# the following conditions:
+#
+# The above copyright notice and this permission notice shall be
+# included in all copies or substantial portions of the Software.
+#
+# THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
+# EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
+# MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
+# NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
+# LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, 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 THE SOFTWARE.
+module ExceptionNotifierHelper
+  VIEW_PATH = "views/exception_notifier"
+  APP_PATH = "#{RAILS_ROOT}/app/#{VIEW_PATH}"
+  PARAM_FILTER_REPLACEMENT = "[FILTERED]"
+
+  def render_section(section)
+    RAILS_DEFAULT_LOGGER.info("rendering section #{section.inspect}")
+    summary = render_overridable(section).strip
+    unless summary.blank?
+      title = render_overridable(:title, :locals => { :title => section }).strip
+      "#{title}\n\n#{summary.gsub(/^/, "  ")}\n\n"
+    end
+  end
+
+  def render_overridable(partial, options={})
+    if File.exist?(path = "#{APP_PATH}/_#{partial}.rhtml")
+      render(options.merge(:file => path, :use_full_path => false))
+    elsif File.exist?(path = "#{File.dirname(__FILE__)}/../#{VIEW_PATH}/_#{partial}.rhtml")
+      render(options.merge(:file => path, :use_full_path => false))
+    else
+      ""
+    end
+  end
+
+  def inspect_model_object(model, locals={})
+    render_overridable(:inspect_model,
+      :locals => { :inspect_model => model,
+                   :show_instance_variables => true,
+                   :show_attributes => true }.merge(locals))
+  end
+
+  def inspect_value(value)
+    len = 512
+    result = object_to_yaml(value).gsub(/\n/, "\n  ").strip
+    result = result[0,len] + "... (#{result.length-len} bytes more)" if result.length > len+20
+    result
+  end
+
+  def object_to_yaml(object)
+    object.to_yaml.sub(/^---\s*/m, "")
+  end
+
+  def exclude_raw_post_parameters?
+    @controller && @controller.respond_to?(:filter_parameters)
+  end
+  
+  def filter_sensitive_post_data_parameters(parameters)
+    exclude_raw_post_parameters? ? @controller.__send__(:filter_parameters, parameters) : parameters
+  end
+  
+  def filter_sensitive_post_data_from_env(env_key, env_value)
+    return env_value unless exclude_raw_post_parameters?
+    return PARAM_FILTER_REPLACEMENT if (env_key =~ /RAW_POST_DATA/i)
+    return @controller.__send__(:filter_parameters, {env_key => env_value}).values[0]
+  end
+end