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.

Class Public methods

logger(*args, **kwargs)

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

📝 Source code

# File activesupport/lib/active_support/tagged_logging.rb, line 117
    def self.logger(*args, **kwargs)
      new ActiveSupport::Logger.new(*args, **kwargs)
    end

🔎 See on GitHub

new(logger)

📝 Source code

# File activesupport/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

🔎 See on GitHub

Instance Public methods

flush()

📝 Source code

# File activesupport/lib/active_support/tagged_logging.rb, line 152
    def flush
      clear_tags!
      super if defined?(super)
    end

🔎 See on GitHub

tagged(*tags)

📝 Source code

# File activesupport/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

🔎 See on GitHub