class Rack::CommonLogger

Rack::CommonLogger forwards every request to the given app, and logs a line in the Apache common log format to the configured logger.

Constants

FORMAT

Common Log Format: httpd.apache.org/docs/1.3/logs.html#common

lilith.local - - [07/Aug/2006 23:58:02 -0400] "GET / HTTP/1.1" 500 -

%{%s - %s [%s] "%s %s%s %s" %d %s\n} %

The actual format is slightly different than the above due to the separation of SCRIPT_NAME and PATH_INFO, and because the elapsed time in seconds is included at the end.

Public Class Methods

new(app, logger = nil) click to toggle source

logger can be any object that supports the write or +<<+ methods, which includes the standard library Logger. These methods are called with a single string argument, the log message. If logger is nil, CommonLogger will fall back env['rack.errors'].

# File lib/rack/common_logger.rb, line 23
def initialize(app, logger = nil)
  @app = app
  @logger = logger
end

Public Instance Methods

call(env) click to toggle source

Log all requests in common_log format after a response has been returned. Note that if the app raises an exception, the request will not be logged, so if exception handling middleware are used, they should be loaded after this middleware. Additionally, because the logging happens after the request body has been fully sent, any exceptions raised during the sending of the response body will cause the request not to be logged.

# File lib/rack/common_logger.rb, line 35
def call(env)
  began_at = Utils.clock_time
  status, headers, body = @app.call(env)
  headers = Utils::HeaderHash[headers]
  body = BodyProxy.new(body) { log(env, status, headers, began_at) }
  [status, headers, body]
end

Private Instance Methods

extract_content_length(headers) click to toggle source

Attempt to determine the content length for the response to include it in the logged data.

# File lib/rack/common_logger.rb, line 74
def extract_content_length(headers)
  value = headers[CONTENT_LENGTH]
  !value || value.to_s == '0' ? '-' : value
end

log(env, status, header, began_at) click to toggle source

Log the request to the configured logger.

# File lib/rack/common_logger.rb, line 46
def log(env, status, header, began_at)
  length = extract_content_length(header)

  msg = FORMAT % [
    env['HTTP_X_FORWARDED_FOR'] || env["REMOTE_ADDR"] || "-",
    env["REMOTE_USER"] || "-",
    Time.now.strftime("%d/%b/%Y:%H:%M:%S %z"),
    env[REQUEST_METHOD],
    env[SCRIPT_NAME],
    env[PATH_INFO],
    env[QUERY_STRING].empty? ? "" : "?#{env[QUERY_STRING]}",
    env[SERVER_PROTOCOL],
    status.to_s[0..3],
    length,
    Utils.clock_time - began_at ]

  logger = @logger || env[RACK_ERRORS]
  # Standard library logger doesn't support write but it supports << which actually
  # calls to write on the log device without formatting
  if logger.respond_to?(:write)
    logger.write(msg)
  else
    logger << msg
  end
end