Class: Syslog::Logger

Inherits:
Object
  • Object
show all
Defined in:
lib/syslog/logger.rb

Overview

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.

Defined Under Namespace

Classes: Formatter

Constant Summary collapse

VERSION =

The version of Syslog::Logger you are using.

'2.0'
LEVEL_MAP =

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).

{
  ::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,
}

Instance Attribute Summary collapse

Class Method Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(program_name = 'ruby', facility = nil) ⇒ Logger

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.


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# File 'lib/syslog/logger.rb', line 190

def initialize program_name = 'ruby', facility = nil
  @level = ::Logger::DEBUG
  @formatter = Formatter.new

  @@syslog ||= Syslog.open(program_name)

  @facility = (facility || @@syslog.facility)
end

Instance Attribute Details

#facilityObject

The facility argument is used to specify what type of program is logging the message.


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# File 'lib/syslog/logger.rb', line 181

def facility
  @facility
end

#formatterObject

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.


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# File 'lib/syslog/logger.rb', line 176

def formatter
  @formatter
end

#levelObject

Log level for Logger compatibility.


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# File 'lib/syslog/logger.rb', line 162

def level
  @level
end

Class Method Details

.make_methods(meth) ⇒ Object

Builds a methods for level meth.


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# File 'lib/syslog/logger.rb', line 106

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

.syslogObject

Returns the internal Syslog object that is initialized when the first instance is created.


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# File 'lib/syslog/logger.rb', line 92

def self.syslog
  @@syslog
end

.syslog=(syslog) ⇒ Object

Specifies the internal Syslog object to be used.


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# File 'lib/syslog/logger.rb', line 99

def self.syslog= syslog
  @@syslog = syslog
end

Instance Method Details

#add(severity, message = nil, progname = nil, &block) ⇒ Object

Almost duplicates Logger#add. progname is ignored.


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# File 'lib/syslog/logger.rb', line 202

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

#severityObject

:method: debug

Logs a message at the debug (syslog debug) log level, or logs the message returned from the block.


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# File 'lib/syslog/logger.rb', line 155

Logger::Severity::constants.each do |severity|
  make_methods severity.downcase
end