Support for logging to syslog

README.md

@@ -8,7 +8,7 @@ writing to a file or syslog since logstash can receive the structured data direc
 ## Features
 
 * Can write directly to logstash over a UDP or TCP/SSL connection.
-* Can write to a file, Redis, a unix socket, stdout or stderr.
+* Can write to a file, Redis, Kafka, a unix socket, syslog, stdout, or stderr.
 * Writes in logstash JSON format, but supports other formats as well.
 * Can write to multiple outputs.
 * Logger can take a string message, a hash, a `LogStash::Event`, an object, or a JSON string as input.
@@ -44,6 +44,7 @@ tcp_logger = LogStashLogger.new(type: :tcp, host: 'localhost', port: 5229)
 # Other types of loggers
 file_logger = LogStashLogger.new(type: :file, path: 'log/development.log', sync: true)
 unix_logger = LogStashLogger.new(type: :unix, path: '/tmp/sock')
+syslog_logger = LogStashLogger.new(type: :syslog)
 redis_logger = LogStashLogger.new(type: :redis)
 kafka_logger = LogStashLogger.new(type: :kafka)
 stdout_logger = LogStashLogger.new(type: :stdout)
@@ -75,14 +76,16 @@ ruby_default_formatter_logger = LogStashLogger.new(
 )
 
 # Send messages to multiple outputs. Each output will have the same format.
+# Syslog cannot be an output because it requires a separate logger.
 multi_delegating_logger = LogStashLogger.new(
   type: :multi_delegator,
   outputs: [
     { type: :file, path: 'log/development.log' },
     { type: :udp, host: 'localhost', port: 5228 }
   ])
 
-# Balance messages between several outputs
+# Balance messages between several outputs.
+# Works the same as multi delegator, but randomly chooses an output to send each message.
 balancer_logger = LogStashLogger.new(
   type: :balancer,
   outputs: [
@@ -92,6 +95,7 @@ balancer_logger = LogStashLogger.new(
 
 # Send messages to multiple loggers.
 # Use this if you need to send different formats to different outputs.
+# If you need to log to syslog, you must use this.
 multi_logger = LogStashLogger.new(
   type: :multi_logger,
   outputs: [
@@ -305,6 +309,25 @@ config.logstash.type = :unix
 config.logstash.path = '/tmp/sock'
 ```
 
+#### Syslog
+
+If you're on Ruby 1.9, add `Syslog::Logger` v2 to your Gemfile:
+
+    gem 'SyslogLogger', '2.0'
+
+If you're on Ruby 2+, `Syslog::Logger` is already built into the standard library.
+
+```ruby
+# Required
+config.logstash.type = :syslog
+
+# Optional. Defaults to 'ruby'
+config.logstash.program_name = 'MyApp'
+
+# Optional default facility level. Only works in Ruby 2+
+config.logstash.facility = Syslog::LOG_LOCAL0
+```
+
 #### Redis
 
 Add the redis gem to your Gemfile:

lib/logstash-logger/logger.rb

@@ -1,6 +1,11 @@
 require 'logger'
 require 'logstash-logger/tagged_logging'
 
+autoload :Syslog, 'syslog'
+module Syslog
+  autoload :Logger, 'syslog/logger'
+end
+
 module LogStashLogger
   autoload :MultiLogger, 'logstash-logger/multi_logger'
 
@@ -45,20 +50,45 @@ def self.extract_opts(*args)
   end
 
   def self.build_logger(opts)
-    case opts[:type]
+    formatter = Formatter.new(opts.delete(:formatter))
+
+    logger = case opts[:type]
     when :multi_logger
-      loggers = opts[:outputs].map {|logger_opts| build_logger(logger_opts) }
-      MultiLogger.new(loggers)
+      build_multi_logger(opts)
+    when :syslog
+      build_syslog_logger(opts)
     else
-      formatter = Formatter.new(opts.delete(:formatter))
-      device = Device.new(opts)
-
-      ::Logger.new(device).tap do |logger|
-        logger.instance_variable_set(:@device, device)
-        logger.extend(self)
-        logger.extend(TaggedLogging)
-        logger.formatter = formatter
-      end
+      build_default_logger(opts)
     end
+
+    logger.formatter = formatter if formatter
+    logger
+  end
+
+  private
+
+  def self.build_default_logger(opts)
+    device = Device.new(opts)
+    ::Logger.new(device).tap do |logger|
+      logger.instance_variable_set(:@device, device)
+      logger.extend(self)
+      logger.extend(TaggedLogging)
+    end
+  end
+
+  def self.build_multi_logger(opts)
+    loggers = opts[:outputs].map { |logger_opts| build_logger(logger_opts) }
+    MultiLogger.new(loggers)
+  end
+
+  def self.build_syslog_logger(opts)
+    logger = begin
+      Syslog::Logger.new(opts[:program_name], opts[:facility])
+    rescue ArgumentError
+      Syslog::Logger.new(opts[:program_name])
+    end
+
+    logger.extend(self)
+    logger.extend(TaggedLogging)
   end
 end

logstash-logger.gemspec

@@ -25,6 +25,10 @@ Gem::Specification.new do |gem|
   gem.add_development_dependency 'redis'
   gem.add_development_dependency 'poseidon'
 
+  if RUBY_VERSION < '2'
+    gem.add_development_dependency 'SyslogLogger'
+  end
+
   gem.add_development_dependency 'rspec', '>= 3'
   gem.add_development_dependency 'rake'
   gem.add_development_dependency 'pry'

samples/syslog.conf

@@ -0,0 +1,10 @@
+input {
+  syslog {
+    codec => json_lines
+  }
+}
+output {
+  stdout {
+    codec => json_lines
+  }
+}

spec/syslog_spec.rb

@@ -0,0 +1,25 @@
+require 'logstash-logger'
+
+describe LogStashLogger do
+  context "Syslog" do
+    let(:program_name) { "MyApp" }
+    let(:facility) { Syslog::LOG_LOCAL0 }
+    subject { LogStashLogger.new(type: :syslog, program_name: program_name, facility: facility) }
+    let(:syslog) { subject.class.class_variable_get(:@@syslog) }
+
+    it { is_expected.to be_a Syslog::Logger }
+
+    it "writes formatted messages to syslog" do
+      expect(syslog).to receive(:log)
+      subject.info("test")
+    end
+
+    it "sets the syslog identity" do
+      expect(syslog.ident).to eq(program_name)
+    end
+
+    it "sets the default facility if supported" do
+      expect(subject.facility).to eq(facility) if subject.respond_to?(:facility)
+    end
+  end
+end