Custom logger (#2770)

* Add ability to specify custom logger

* Add test

* Use regex match

* Add custom logging in the log writer

* Write to custom logger instead of stdout if custom logger is present

* Check that the custom logger responds to write

* Use safe navigation

* Initialize to prevent warning

* Move test to not run parallel

* Update lib/puma/dsl.rb

Co-authored-by: Jack <5182053+phyzical@users.noreply.github.com>

* Update lib/puma/launcher.rb

Co-authored-by: Jack <5182053+phyzical@users.noreply.github.com>

* Update test/test_config.rb

Co-authored-by: Jack <5182053+phyzical@users.noreply.github.com>

* Update test/test_config.rb

Co-authored-by: Jack <5182053+phyzical@users.noreply.github.com>

* Update test/config/custom_logger.rb

Co-authored-by: Jack <5182053+phyzical@users.noreply.github.com>

---------

Co-authored-by: Jack <5182053+phyzical@users.noreply.github.com>

lib/puma/dsl.rb

@@ -419,6 +419,11 @@ def log_requests(which=true)
       @options[:log_requests] = which
     end
 
+    # Pass in a custom logging class instance
+    def custom_logger(custom_logger)
+      @options[:custom_logger] = custom_logger
+    end
+
     # Show debugging info
     #
     def debug

lib/puma/launcher.rb

@@ -79,6 +79,8 @@ def initialize(conf, launcher_args={})
       @log_writer.formatter = LogWriter::PidFormatter.new if clustered?
       @log_writer.formatter = options[:log_formatter] if @options[:log_formatter]
 
+      @log_writer.custom_logger = options[:custom_logger] if @options[:custom_logger]
+
       generate_restart_data
 
       if clustered? && !Puma.forkable?

lib/puma/log_writer.rb

@@ -28,11 +28,12 @@ def call(str)
     attr_reader :stdout,
                 :stderr
 
-    attr_accessor :formatter
+    attr_accessor :formatter, :custom_logger
 
     # Create a LogWriter that prints to +stdout+ and +stderr+.
     def initialize(stdout, stderr)
       @formatter = DefaultFormatter.new
+      @custom_logger = nil
       @stdout = stdout
       @stderr = stderr
 
@@ -59,7 +60,11 @@ def self.null
 
     # Write +str+ to +@stdout+
     def log(str)
-      internal_write "#{@formatter.call str}\n"
+      if @custom_logger&.respond_to?(:write)
+        @custom_logger.write(format(str))
+      else
+        internal_write "#{@formatter.call str}\n"
+      end
     end
 
     def write(str)

test/config/custom_logger.rb

@@ -0,0 +1,13 @@
+class CustomLogger
+  def initialize(output=STDOUT)
+    @output = output
+  end
+
+  def write(msg)
+    @output.puts 'Custom logging: ' + msg
+    @output.flush
+  end
+end
+
+log_requests
+custom_logger CustomLogger.new(STDOUT)

test/test_config.rb

@@ -595,6 +595,18 @@ def assert_warning_for_hooks_defined_in_single_mode(hook_name)
   end
 end
 
+# contains tests that cannot run parallel
+class TestConfigFileSingle < TestConfigFileBase
+  def test_custom_logger_from_DSL
+    conf = Puma::Configuration.new { |c| c.load 'test/config/custom_logger.rb' }
+
+    conf.load
+    out, _ = capture_subprocess_io { conf.options[:custom_logger].write 'test' }
+
+    assert_equal "Custom logging: test\n", out
+  end
+end
+
 # Thread unsafe modification of ENV
 class TestEnvModifificationConfig < TestConfigFileBase
   def test_double_bind_port