Initial Commit

gxg/standard/syslog/logger.rb

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+# frozen_string_literal: false
+require 'syslog'
+require 'logger'
+
+##
+# Syslog::Logger is a Logger work-alike that logs via syslog instead of to a
+# file.  You can use Syslog::Logger to aggregate logs between multiple
+# machines.
+#
+# By default, Syslog::Logger uses the program name 'ruby', but this can be
+# changed via the first argument to Syslog::Logger.new.
+#
+# NOTE! You can only set the Syslog::Logger program name when you initialize
+# Syslog::Logger for the first time.  This is a limitation of the way
+# Syslog::Logger uses syslog (and in some ways, a limitation of the way
+# syslog(3) works).  Attempts to change Syslog::Logger's program name after
+# the first initialization will be ignored.
+#
+# === Example
+#
+# The following will log to syslogd on your local machine:
+#
+#   require 'syslog/logger'
+#
+#   log = Syslog::Logger.new 'my_program'
+#   log.info 'this line will be logged via syslog(3)'
+#
+# Also the facility may be set to specify the facility level which will be used:
+#
+#   log.info 'this line will be logged using Syslog default facility level'
+#
+#   log_local1 = Syslog::Logger.new 'my_program', Syslog::LOG_LOCAL1
+#   log_local1.info 'this line will be logged using local1 facility level'
+#
+#
+# You may need to perform some syslog.conf setup first.  For a BSD machine add
+# the following lines to /etc/syslog.conf:
+#
+#  !my_program
+#  *.*                                             /var/log/my_program.log
+#
+# Then touch /var/log/my_program.log and signal syslogd with a HUP
+# (killall -HUP syslogd, on FreeBSD).
+#
+# If you wish to have logs automatically roll over and archive, see the
+# newsyslog.conf(5) and newsyslog(8) man pages.
+
+class Syslog::Logger
+  # Default formatter for log messages.
+  class Formatter
+    def call severity, time, progname, msg
+      clean msg
+    end
+
+    private
+
+    ##
+    # Clean up messages so they're nice and pretty.
+
+    def clean message
+      message = message.to_s.strip
+      message.gsub!(/\e\[[0-9;]*m/, '') # remove useless ansi color codes
+      return message
+    end
+  end
+
+  ##
+  # The version of Syslog::Logger you are using.
+
+  VERSION = '2.1.0'
+
+  ##
+  # Maps Logger warning types to syslog(3) warning types.
+  #
+  # Messages from Ruby applications are not considered as critical as messages
+  # from other system daemons using syslog(3), so most messages are reduced by
+  # one level.  For example, a fatal message for Ruby's Logger is considered
+  # an error for syslog(3).
+
+  LEVEL_MAP = {
+    ::Logger::UNKNOWN => Syslog::LOG_ALERT,
+    ::Logger::FATAL   => Syslog::LOG_ERR,
+    ::Logger::ERROR   => Syslog::LOG_WARNING,
+    ::Logger::WARN    => Syslog::LOG_NOTICE,
+    ::Logger::INFO    => Syslog::LOG_INFO,
+    ::Logger::DEBUG   => Syslog::LOG_DEBUG,
+  }
+
+  ##
+  # Returns the internal Syslog object that is initialized when the
+  # first instance is created.
+
+  def self.syslog
+    @@syslog
+  end
+
+  ##
+  # Specifies the internal Syslog object to be used.
+
+  def self.syslog= syslog
+    @@syslog = syslog
+  end
+
+  ##
+  # Builds a methods for level +meth+.
+
+  def self.make_methods meth
+    level = ::Logger.const_get(meth.upcase)
+    eval <<-EOM, nil, __FILE__, __LINE__ + 1
+      def #{meth}(message = nil, &block)
+        add(#{level}, message, &block)
+      end
+
+      def #{meth}?
+        @level <= #{level}
+      end
+    EOM
+  end
+
+  ##
+  # :method: unknown
+  #
+  # Logs a +message+ at the unknown (syslog alert) log level, or logs the
+  # message returned from the block.
+
+  ##
+  # :method: fatal
+  #
+  # Logs a +message+ at the fatal (syslog err) log level, or logs the message
+  # returned from the block.
+
+  ##
+  # :method: error
+  #
+  # Logs a +message+ at the error (syslog warning) log level, or logs the
+  # message returned from the block.
+
+  ##
+  # :method: warn
+  #
+  # Logs a +message+ at the warn (syslog notice) log level, or logs the
+  # message returned from the block.
+
+  ##
+  # :method: info
+  #
+  # Logs a +message+ at the info (syslog info) log level, or logs the message
+  # returned from the block.
+
+  ##
+  # :method: debug
+  #
+  # Logs a +message+ at the debug (syslog debug) log level, or logs the
+  # message returned from the block.
+
+  Logger::Severity::constants.each do |severity|
+    make_methods severity.downcase
+  end
+
+  ##
+  # Log level for Logger compatibility.
+
+  attr_accessor :level
+
+  # Logging formatter, as a +Proc+ that will take four arguments and
+  # return the formatted message. The arguments are:
+  #
+  # +severity+:: The Severity of the log message.
+  # +time+:: A Time instance representing when the message was logged.
+  # +progname+:: The #progname configured, or passed to the logger method.
+  # +msg+:: The _Object_ the user passed to the log message; not necessarily a
+  #         String.
+  #
+  # The block should return an Object that can be written to the logging
+  # device via +write+.  The default formatter is used when no formatter is
+  # set.
+  attr_accessor :formatter
+
+  ##
+  # The facility argument is used to specify what type of program is logging the message.
+
+  attr_accessor :facility
+
+  ##
+  # Fills in variables for Logger compatibility.  If this is the first
+  # instance of Syslog::Logger, +program_name+ may be set to change the logged
+  # program name. The +facility+ may be set to specify the facility level which will be used.
+  #
+  # Due to the way syslog works, only one program name may be chosen.
+
+  def initialize program_name = 'ruby', facility = nil
+    @level = ::Logger::DEBUG
+    @formatter = Formatter.new
+
+    @@syslog ||= Syslog.open(program_name)
+
+    @facility = (facility || @@syslog.facility)
+  end
+
+  ##
+  # Almost duplicates Logger#add.  +progname+ is ignored.
+
+  def add severity, message = nil, progname = nil, &block
+    severity ||= ::Logger::UNKNOWN
+    @level <= severity and
+      @@syslog.log( (LEVEL_MAP[severity] | @facility), '%s', formatter.call(severity, Time.now, progname, (message || block.call)) )
+    true
+  end
+end