Custom formatter

config/environments/development.rb

@@ -14,6 +14,9 @@ Rails.application.configure do
   # Do not eager load code on boot.
   config.eager_load = false
 
+  require 'custom_log_formatter'
+  config.log_formatter = CustomLogFormatter.new
+
   # Show full error reports and disable caching.
   config.consider_all_requests_local       = true
   config.action_controller.perform_caching = false

config/environments/production.rb

@@ -10,7 +10,12 @@ Rails.application.configure do
   # require 'syslog/logger'
   # config.logger = ActiveSupport::TaggedLogging.new(Syslog::Logger.new 'app-name')
 
-  config.logger = ActiveSupport::Logger.new(config.paths['log'].first, 1, 50 * 1024 * 1024)
+  MAX_LOG_MEGABYTES = 50
+  config.logger = ActiveSupport::Logger.new(config.paths['log'].first, 1, MAX_LOG_MEGABYTES * 1024 * 1024)
+
+  require 'custom_log_formatter'
+  config.log_formatter = CustomLogFormatter.new
+  config.logger.formatter = config.log_formatter
 
   if ENV["RAILS_LOG_TO_STDOUT"].present?
     logger           = ActiveSupport::Logger.new(STDOUT)

lib/custom_log_formatter.rb

@@ -0,0 +1,18 @@
+class CustomLogFormatter < ActiveSupport::Logger::SimpleFormatter
+  SEVERITY_TO_COLOR_MAP = {'DEBUG'=>'0;37', 'INFO'=>'32', 'WARN'=>'33', 'ERROR'=>'31', 'FATAL'=>'31', 'UNKNOWN'=>'37'}
+
+  IPRegexp = /\b(?:[0-9]{1,3}\.){3}[0-9]{1,3}\b/
+  FilteredString = '**FILTERED**'
+
+  def call(severity, time, progname, msg)
+    formatted_severity = sprintf("%-5s","#{severity}")
+    formatted_time = time.strftime("%Y-%m-%d %H:%M:%S.") << time.usec.to_s[0..2].rjust(3)
+    color = SEVERITY_TO_COLOR_MAP[severity]
+
+    "\033[0;37m#{formatted_time}\033[0m [\033[#{color}m#{formatted_severity}\033[0m] #{filter_ip(msg.strip)} (pid:#{$$})\n"
+  end
+
+  def filter_ip(msg)
+    msg.gsub(IPRegexp, FilteredString)
+  end
+end