Adds logging. Closes #583

README.md

@@ -120,6 +120,16 @@ environment information on the callback request. It is entirely up to
 you how you want to implement the particulars of your application's
 authentication flow.
 
+## Logging
+
+OmniAuth supports a configurable logger. By default, OmniAuth will log 
+to `STDOUT` but you can configure this using `OmniAuth.config.logger`:
+
+```ruby
+# Rails application example
+OmniAuth.config.logger = Rails.logger
+```
+
 ## <a name="resources"></a>Resources
 
 The [OmniAuth Wiki](https://github.com/intridea/omniauth/wiki) has

lib/omniauth.rb

@@ -1,5 +1,6 @@
 require 'rack'
 require 'singleton'
+require 'logger'
 
 module OmniAuth
   class Error < StandardError; end
@@ -22,12 +23,19 @@ module OmniAuth
   class Configuration
     include Singleton
 
+    def self.default_logger
+      logger = Logger.new(STDOUT)
+      logger.progname = "omniauth"
+      logger
+    end
+
     @@defaults = {
       :camelizations => {},
       :path_prefix => '/auth',
       :on_failure => OmniAuth::FailureEndpoint,
       :form_css => Form::DEFAULT_CSS,
       :test_mode => false,
+      :logger => default_logger,
       :allowed_request_methods => [:get, :post],
       :mock_auth => {
         :default => AuthHash.new(
@@ -88,7 +96,7 @@ module OmniAuth
     end
 
     attr_writer :on_failure
-    attr_accessor :path_prefix, :allowed_request_methods, :form_css, :test_mode, :mock_auth, :full_host, :camelizations
+    attr_accessor :path_prefix, :allowed_request_methods, :form_css, :test_mode, :mock_auth, :full_host, :camelizations, :logger
   end
 
   def self.config
@@ -99,6 +107,10 @@ module OmniAuth
     yield config
   end
 
+  def self.logger
+    config.logger
+  end
+
   def self.mock_auth_for(provider)
     config.mock_auth[provider.to_sym] || config.mock_auth[:default]
   end

lib/omniauth/strategy.rb

@@ -142,6 +142,15 @@ module OmniAuth
       "#<#{self.class.to_s}>"
     end
 
+    # Direct access to the OmniAuth logger, automatically prefixed
+    # with this strategy's name.
+    #
+    # @example
+    #   log :warn, "This is a warning."
+    def log(level, message)
+      OmniAuth.logger.send(level, "(#{name}) #{message}")
+    end
+
     # Duplicates this instance and runs #call! on it.
     # @param [Hash] The Rack environment.
     def call(env)
@@ -178,12 +187,16 @@ module OmniAuth
     def request_call
       setup_phase
 
+      log :info, "Request phase initiated."
+
       #store query params from the request url, extracted in the callback_phase
       session['omniauth.params'] = request.params
 
       if options.form.respond_to?(:call)
+        log :info, "Rendering form from supplied Rack endpoint."
         options.form.call(env)
       elsif options.form
+        log :info, "Rendering form from underlying application."
         call_app!
       else
         if request.params['origin']
@@ -198,6 +211,8 @@ module OmniAuth
     # Performs the steps necessary to run the callback phase of a strategy.
     def callback_call
       setup_phase
+
+      log :info, "Callback phase initiated."
       @env['omniauth.origin'] = session.delete('omniauth.origin')
       @env['omniauth.origin'] = nil if env['omniauth.origin'] == ''
       @env['omniauth.params'] = session.delete('omniauth.params') || {}
@@ -266,8 +281,10 @@ module OmniAuth
     # underlying application. This will default to `/auth/:provider/setup`.
     def setup_phase
       if options[:setup].respond_to?(:call)
+        log :info, "Setup endpoint detected, running now."
         options[:setup].call(env)
       elsif options.setup?
+        log :info, "Calling through to underlying application for setup."
         setup_env = env.merge('PATH_INFO' => setup_path, 'REQUEST_METHOD' => 'GET')
         call_app!(setup_env)
       end
@@ -413,6 +430,12 @@ module OmniAuth
       self.env['omniauth.error.type'] = message_key.to_sym
       self.env['omniauth.error.strategy'] = self
 
+      if exception
+        log :error, "Authentication failure! #{message_key}: #{exception.class.to_s}, #{exception.message}"
+      else
+        log :error, "Authentication failure! #{message_key} encountered."
+      end
+
       OmniAuth.config.on_failure.call(self.env)
     end
 

spec/omniauth_spec.rb

@@ -76,6 +76,13 @@ describe OmniAuth do
     end
   end
 
+  describe '.logger' do
+    it 'should call through to the configured logger' do
+      OmniAuth.stub(:config => mock(:logger => "foo"))
+      OmniAuth.logger.should == "foo"
+    end
+  end
+
   describe '::Utils' do
     describe '.deep_merge' do
       it 'should combine hashes' do

spec/spec_helper.rb

@@ -8,6 +8,8 @@ require 'rack/test'
 require 'omniauth'
 require 'omniauth/test'
 
+OmniAuth.config.logger = Logger.new("/dev/null")
+
 RSpec.configure do |config|
   config.include Rack::Test::Methods
   config.extend  OmniAuth::Test::StrategyMacros, :type => :strategy