Overwrite middleware to handle errors in logstash compatible format.

Closes shadabahmed#79

lib/logstasher.rb

@@ -4,6 +4,7 @@
 require 'logstasher/active_record/log_subscriber'
 require 'logstasher/action_view/log_subscriber'
 require 'logstasher/rails_ext/action_controller/base'
+require 'logstasher/rails_ext/rack/debug_exceptions'
 require 'request_store'
 require 'active_support/core_ext/module/attribute_accessors'
 require 'active_support/core_ext/string/inflections'
@@ -137,6 +138,16 @@ def configured_to_suppress_app_logs?(config)
     !!(config.suppress_app_log.nil? ? config.supress_app_log : config.suppress_app_log)
   end
 
+  def modify_middleware(app)
+    if enabled
+      if configured_to_suppress_app_logs? app.config.logstasher
+        app.middleware.swap ::ActionDispatch::DebugExceptions, ::LogStasher::ActionDispatch::DebugExceptions
+      else
+        app.middleware.swap ::ActionDispatch::DebugExceptions, ::LogStasher::ActionDispatch::TwoWayDebugExceptions
+      end
+    end
+  end
+
   def custom_fields
     Thread.current[:logstasher_custom_fields] ||= []
   end

lib/logstasher/rails_ext/rack/debug_exceptions.rb

@@ -0,0 +1,38 @@
+require 'action_dispatch'
+require 'active_support/all'
+
+module LogStasher
+  module ActionDispatch
+    def build_exception_hash(wrapper)
+      exception = wrapper.exception
+      trace = wrapper.application_trace
+      trace = wrapper.framework_trace if trace.empty?
+
+      { error:
+        ({ exception: exception.class.name, message: exception.message, trace: trace}.
+         merge!( exception.respond_to?(:annotated_source_code) && { annotated_source_code: exception.annoted_source_code } || {} ))
+      }
+    end
+
+    class DebugExceptions < ::ActionDispatch::DebugExceptions
+      include ::LogStasher::ActionDispatch
+
+      private
+      def log_error(env, wrapper)
+        LogStasher.logger << LogStasher.build_logstash_event(build_exception_hash(wrapper), ["exception"]).to_json + "\n"
+      end
+
+    end
+
+    class TwoWayDebugExceptions < ::ActionDispatch::DebugExceptions
+      include ::LogStasher::ActionDispatch
+
+      private
+      def log_error(env, wrapper)
+        LogStasher.logger << LogStasher.build_logstash_event(build_exception_hash(wrapper), ["exception"]).to_json + "\n"
+
+        super(env, wrapper)
+      end
+    end
+  end
+end

lib/logstasher/railtie.rb

@@ -2,6 +2,8 @@
 require 'action_view/log_subscriber'
 require 'action_controller/log_subscriber'
 require 'socket'
+require 'action_dispatch'
+require 'active_support/all'
 
 module LogStasher
   class Railtie < Rails::Railtie
@@ -21,7 +23,7 @@ class Railtie < Rails::Railtie
     # Load and ERB templating of YAML files
     LOGSTASHER = File.exists?(config_file) ? YAML.load(ERB.new(File.read(config_file)).result).symbolize_keys : nil
 
-    initializer :logstasher, :before => :load_config_initializers do |app|
+    initializer :logstasher, before: :load_config_initializers do |app|
       if LOGSTASHER.present?
         # process common configs
         LogStasher.process_config(app.config.logstasher, LOGSTASHER)
@@ -38,6 +40,10 @@ class Railtie < Rails::Railtie
         LogStasher.setup(config.logstasher) if config.logstasher.enabled
       end
     end
+
+    initializer 'logstasher.insert_middleware', after: :load_config_initializers do |app|
+      LogStasher.modify_middleware app
+    end
   end
 
   def process_config(config, yml_config)

spec/lib/logstasher/rails_ext/rack/debug_exceptions_spec.rb

@@ -0,0 +1,72 @@
+require 'spec_helper'
+
+shared_examples 'MyApp' do
+  before do
+    class MyApp 
+      def initialize()
+      end
+      def call(*args)
+        raise Exception.new("My Exception")
+      end
+    end
+  end
+
+  let(:app) { MyApp.new }
+  let(:environment) { { 'action_dispatch.show_exceptions' => true } } 
+  let(:logger) { double }
+  subject{ described_class.new(app) }
+
+  before(:each) do
+    allow(LogStasher).to receive(:logger).and_return(logger)
+    allow(LogStasher.logger).to receive(:'<<').and_return(true)
+  end
+end
+
+shared_examples 'build_exception_hash' do
+  describe '#build_exception_hash' do
+    let (:wrapper) { double(exception: Exception.new("My Exception"), application_trace: [ "line5" ]) }
+    it do
+      hash = subject.build_exception_hash(wrapper)
+
+      expect(hash).to match({:error=>{:exception=>"Exception", :message=>"My Exception", :trace=>["line5"]}})
+    end
+  end
+end
+
+describe ::LogStasher::ActionDispatch::DebugExceptions do
+  include_examples 'MyApp'
+
+  describe 'calls LogStasher.logger with json format exception' do
+    describe '#log_error' do
+      it do
+        expect(LogStasher).to receive(:build_logstash_event)
+        expect(LogStasher.logger).to receive(:'<<').and_return(true)
+        expect{ subject.call(environment) }.to raise_error(Exception, "My Exception")
+      end
+    end
+  end
+
+  include_examples 'build_exception_hash'
+end
+
+describe ::LogStasher::ActionDispatch::TwoWayDebugExceptions do
+  include_examples 'MyApp'
+
+  let(:logger_2nd) { double }
+  before(:each) do
+    allow(subject).to receive(:logger).and_return(logger_2nd)
+  end
+
+  describe 'calls LogStasher.logger with json format exception' do
+    describe '#log_error' do
+      it do
+        expect(LogStasher).to receive(:build_logstash_event)
+        expect(LogStasher.logger).to receive(:'<<').and_return(true)
+        expect(logger_2nd).to receive(:fatal).and_return(true)
+        expect{ subject.call(environment) }.to raise_error(Exception, "My Exception")
+      end
+    end
+  end
+
+  include_examples 'build_exception_hash'
+end