Add timeout option

README.md

@@ -148,6 +148,14 @@ 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`
 
+#### connect_timeout (Integer)
+
+Specify timeout in seconds from connecting. This parameter is available with Ruby 3.0 or above. Default: `nil`
+
+#### resolve_timeout (Integer)
+
+Specify timeout in seconds from when the hostname resolution starts. This parameter is available with Ruby 3.0 or above. Default: `nil`
+
 #### buffer_overflow_handler (Proc)
 
 Pass callback for handling buffer overflow with pending data. See "Buffer overflow" section.

lib/fluent/logger/fluent_logger.rb

@@ -115,6 +115,9 @@ def initialize(tag_prefix = nil, *args)
         @wait_writeable = true
         @wait_writeable = options[:wait_writeable] if options.key?(:wait_writeable)
 
+        @connect_timeout = options[:connect_timeout]
+        @resolv_timeout = options[:resolv_timeout]
+
         @last_error = {}
 
         begin
@@ -170,7 +173,11 @@ def create_socket!
         if @socket_path
           @con = UNIXSocket.new(@socket_path)
         else
-          @con = TCPSocket.new(@host, @port)
+          if supported_timeout?
+            @con = TCPSocket.new(@host, @port, connect_timeout: @connect_timeout, resolv_timeout: @resolv_timeout)
+          else
+            @con = TCPSocket.new(@host, @port)
+          end
           if @tls_options
             context = OpenSSL::SSL::SSLContext.new
             if @tls_options[:insecure]
@@ -378,6 +385,10 @@ def wait_writeable?(e)
           true
         end
       end
+
+      def supported_timeout?
+        @supported_timeout ||= Gem::Version.new(RUBY_VERSION) >= Gem::Version.new('3.0.0')
+      end
     end
   end
 end

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 +435,24 @@ def flush(messages)
       }
     end
   end
+
+  if Gem::Version.new(RUBY_VERSION) >= Gem::Version.new('3.0.0')
+    context "timeout" do
+      it ('support connect_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, connect_timeout: 1)
+          expect(logger.last_error).to be_a_kind_of(IO::TimeoutError)
+        end
+      }
+      it ('support resolv_timeout') {
+        expect {
+          # It just checks that the resolv_timeout option is supported
+          # because it can't use a stub for the DNS resolution.
+          Fluent::Logger::FluentLogger.new(nil, host: 'localhost', port: fluentd.port, resolv_timeout: 1)
+        }.to_not raise_error
+      }
+    end
+  end
 end