module ActiveSupport::TaggedLogging

Active Support Tagged Logging

Wraps any standard Logger object to provide tagging capabilities.

May be called with a block:

logger = ActiveSupport::TaggedLogging.new(Logger.new(STDOUT))
logger.tagged('BCX') { logger.info 'Stuff' }                                  # Logs "[BCX] Stuff"
logger.tagged('BCX', "Jason") { |tagged_logger| tagged_logger.info 'Stuff' }  # Logs "[BCX] [Jason] Stuff"
logger.tagged('BCX') { logger.tagged('Jason') { logger.info 'Stuff' } }       # Logs "[BCX] [Jason] Stuff"

If called without a block, a new logger will be returned with applied tags:

logger = ActiveSupport::TaggedLogging.new(Logger.new(STDOUT))
logger.tagged("BCX").info "Stuff"                 # Logs "[BCX] Stuff"
logger.tagged("BCX", "Jason").info "Stuff"        # Logs "[BCX] [Jason] Stuff"
logger.tagged("BCX").tagged("Jason").info "Stuff" # Logs "[BCX] [Jason] Stuff"

This is used by the default Rails.logger as configured by Railties to make it easy to stamp log lines with subdomains, request ids, and anything else to aid debugging of multi-user production applications.

Public Class Methods

logger(*args, **kwargs) click to toggle source

Returns an ‘ActiveSupport::Logger` that has already been wrapped with tagged logging concern.

# File lib/active_support/tagged_logging.rb, line 117
def self.logger(*args, **kwargs)
  new ActiveSupport::Logger.new(*args, **kwargs)
end
new(logger) click to toggle source
# File lib/active_support/tagged_logging.rb, line 121
def self.new(logger)
  logger = logger.clone

  if logger.formatter
    logger.formatter = logger.formatter.clone

    # Workaround for https://bugs.ruby-lang.org/issues/20250
    # Can be removed when Ruby 3.4 is the least supported version.
    logger.formatter.object_id if logger.formatter.is_a?(Proc)
  else
    # Ensure we set a default formatter so we aren't extending nil!
    logger.formatter = ActiveSupport::Logger::SimpleFormatter.new
  end

  logger.formatter.extend Formatter
  logger.extend(self)
end

Public Instance Methods

flush() click to toggle source
Calls superclass method
# File lib/active_support/tagged_logging.rb, line 152
def flush
  clear_tags!
  super if defined?(super)
end
tagged(*tags) { |self| ... } click to toggle source
# File lib/active_support/tagged_logging.rb, line 141
def tagged(*tags)
  if block_given?
    formatter.tagged(*tags) { yield self }
  else
    logger = ActiveSupport::TaggedLogging.new(self)
    logger.formatter.extend LocalTagStorage
    logger.push_tags(*formatter.current_tags, *tags)
    logger
  end
end