Add timeout option

README.md

@@ -148,6 +148,10 @@ Use nonblocking write(`IO#write_nonblock`) instead of normal write(`IO#write`).
 
 If `false`, `Logger#post` raises an error when nonblocking write gets `EAGAIN` (i.e. `use_nonblock` must be `true`, otherwise this will have no effect).  Default: `true`
 
+#### timeout (Integer)
+
+Specify a timeout in seconds for connecting. Default: `0`
+
 #### buffer_overflow_handler (Proc)
 
 Pass callback for handling buffer overflow with pending data. See "Buffer overflow" section.

lib/fluent/logger/fluent_logger.rb

@@ -22,6 +22,7 @@
 require 'monitor'
 require 'logger'
 require 'json'
+require 'timeout'
 
 module Fluent
   module Logger
@@ -115,6 +116,8 @@ def initialize(tag_prefix = nil, *args)
         @wait_writeable = true
         @wait_writeable = options[:wait_writeable] if options.key?(:wait_writeable)
 
+        @timeout = options[:timeout] || 0
+
         @last_error = {}
 
         begin
@@ -170,7 +173,9 @@ def create_socket!
         if @socket_path
           @con = UNIXSocket.new(@socket_path)
         else
-          @con = TCPSocket.new(@host, @port)
+          @con = Timeout.timeout(@timeout) do
+            TCPSocket.new(@host, @port)
+          end
           if @tls_options
             context = OpenSSL::SSL::SSLContext.new
             if @tls_options[:insecure]

spec/fluent_logger_spec.rb

@@ -6,6 +6,7 @@
 require 'logger'
 require 'stringio'
 require 'fluent/logger/fluent_logger/cui'
+require 'timeout'
 
 describe Fluent::Logger::FluentLogger do
   let(:fluentd) {
@@ -434,4 +435,13 @@ def flush(messages)
       }
     end
   end
+
+  it ('support timeout') {
+    Timeout::timeout(5) do
+      # Use invalid IP address to make sure that the connection will timeout.
+      # (192.0.2.0 is a special IP address that can be used in only documentation. Ref. RFC 5737)
+      logger = Fluent::Logger::FluentLogger.new(nil, host: '192.0.2.0', port: fluentd.port, timeout: 1)
+      expect(logger.last_error).to be_a_kind_of(Timeout::Error)
+    end
+  }
 end