New Fail2ban notifier

README.md

@@ -325,6 +325,34 @@ The API token to allow access to your Campfire account.
 
 For more options to set Campfire, like _ssl_, check [here](https://github.com/collectiveidea/tinder/blob/master/lib/tinder/campfire.rb#L17).
 
+### Fail2ban notifier
+
+This notifier creates a log file you can then parse with [fail2ban](http://www.fail2ban.org/)
+
+#### Usage
+
+To configure the notifier, you don't need anything, although you can customise the `logifile` value, like this:
+
+```ruby
+Whatever::Application.config.middleware.use ExceptionNotification::Rack,
+  :email => {
+    :email_prefix => "[Whatever] ",
+    :sender_address => %{"notifier" <[email protected]>},
+    :exception_recipients => %w{[email protected]}
+  },
+  :fail2ban => {
+    :logfile => '/path/to/logs/fail2ban.log'
+  }
+```
+
+#### Options
+
+##### logfile
+
+*String, not required*
+
+An alternative log file location. By default Rails.root.join('log', 'fail2ban.log')
+
 
 ### HipChat notifier
 

lib/exception_notifier/fail2ban_notifer.rb

@@ -0,0 +1,52 @@
+# This notifier outputs exception details in a log file that you can parse with
+# fail2ban to detect possible attacks..
+#
+# Fail2ban jail configuration (append to /etc/fail2ban/jail.local):
+#
+#   [rails-app]
+#   enabled = true
+#   port = http,https
+#   filter = rails-app
+#   logpath = /path/to/app/log/fail2ban.log
+#   bantime = 3600
+#   findtime = 600
+#   maxretry = 10
+#
+#
+# Fail2ban filter configuration (save in /etc/fail2ban/filters.d/rails-app.conf):
+#   [Definition]
+#   failregex = : <HOST> :
+#   ignoreregex =
+#
+require 'action_dispatch'
+
+module ExceptionNotifier
+  class Fail2banNotifier
+
+    # This notifier only accepts a :logfile option that should point to a valid
+    # file that will be used to log exception entries. Point fail2ban to this
+    # file
+    def initialize(options)
+      @default_options = options
+      @default_options[:logfile] ||= Rails.root.join('log', 'fail2ban.log')
+
+      # Roll over every 30M, keep 10 files
+      @logger ||= Logger.new(@default_options[:logfile], 10, 30*1024*1024)
+    end
+
+    def call(exception, options={})
+      env = options[:env]
+      request = ActionDispatch::Request.new(env)
+
+      # <ip> : <exception class> : <method> <path> -- <params>
+      msg = "%s : %s : %s %s -- %s" % [
+        request.remote_ip,
+        exception.class,
+        request.request_method,
+        env["PATH_INFO"],
+        request.filtered_parameters.inspect
+      ]
+      @logger.error(msg)
+    end
+  end
+end

test/exception_notifier/fail2ban_notifier_test.rb

@@ -0,0 +1,58 @@
+require 'test_helper'
+require 'httparty'
+
+class Fail2banNotifierTest < ActiveSupport::TestCase
+  test "should write exception notification to fail2ban log" do
+    custom_log = Rails.root.join('tmp/fail2ban.log')
+
+    ExceptionNotifier::Fail2banNotifier.stubs(:new).returns(Object.new)
+    fail2ban = ExceptionNotifier::Fail2banNotifier.new({:logfile => custom_log})
+    fail2ban.stubs(:call).returns(fake_response)
+
+    notif = fail2ban.call(fake_exception)
+
+    assert File.exists?(custom_log)
+    last_line = File.read_lines(custom_log).last
+
+    # Very basic test that just verifies we've got a remote IP and an
+    # exception class in no particular order
+    assert last_line.include? fake_response[:body][:request][:ip_address]
+    assert last_line.include? fake_response[:body][:exception][:error_class]
+  end
+
+  private
+
+  def fake_response
+    {
+      :status => 200,
+      :body => {
+        :exception => {
+          :error_class => 'ZeroDivisionError',
+          :message => 'divided by 0',
+          :backtrace => '/exception_notification/test/webhook_notifier_test.rb:48:in `/'
+        },
+        :data => {
+          :extra_data => {:data_item1 => "datavalue1", :data_item2 => "datavalue2"}
+        },
+        :request => {
+          :cookies => {:cookie_item1 => 'cookieitemvalue1', :cookie_item2 => 'cookieitemvalue2'},
+          :url => 'http://example.com/example',
+          :ip_address => '192.168.1.1',
+          :environment => {:env_item1 => "envitem1", :env_item2 => "envitem2"},
+          :controller => '#<ControllerName:0x007f9642a04d00>',
+          :session => {:session_item1 => "sessionitem1", :session_item2 => "sessionitem2"},
+          :parameters => {:action =>"index", :controller =>"projects"}
+        }
+      }
+    }
+  end
+
+  def fake_exception
+    exception = begin
+      5/0
+    rescue Exception => e
+      e
+    end
+  end
+
+end