Log command output

app/models/shipit/task.rb

@@ -186,6 +186,7 @@ def run_now!
     end
 
     def write(text)
+      log_output(text)
       chunks.create!(text: text)
     end
 
@@ -333,5 +334,17 @@ def status_key
     def abort_key
       "#{status_key}:aborting"
     end
+
+    def log_output(text)
+      output_log_line_buffer.buffer(text) do |line|
+        Shipit.task_logger.info(
+          "[#{stack.repo_name}] #{line}"
+        )
+      end
+    end
+
+    def output_log_line_buffer
+      @output_log_line_buffer ||= LineBuffer.new
+    end
   end
 end

lib/shipit.rb

@@ -49,6 +49,7 @@
 require 'shipit/stat'
 require 'shipit/strip_cache_control'
 require 'shipit/cast_value'
+require 'shipit/line_buffer'
 
 SafeYAML::OPTIONS[:default_mode] = :safe
 SafeYAML::OPTIONS[:deserialize_symbols] = false
@@ -59,7 +60,7 @@ module Shipit
   delegate :table_name_prefix, to: :secrets
 
   attr_accessor :disable_api_authentication, :timeout_exit_codes
-  attr_writer :internal_hook_receivers
+  attr_writer :internal_hook_receivers, :task_logger
 
   self.timeout_exit_codes = [].freeze
 
@@ -195,6 +196,10 @@ def internal_hook_receivers
     @internal_hook_receivers ||= []
   end
 
+  def task_logger
+    @task_logger ||= Logger.new(nil)
+  end
+
   protected
 
   def revision_file

lib/shipit/line_buffer.rb

@@ -0,0 +1,34 @@
+module Shipit
+  class LineBuffer
+    def initialize(value = "")
+      @value = value
+    end
+
+    def buffer(text, &block)
+      @value += text
+      whole_lines.each(&block).tap { flush }
+    end
+
+    private
+
+    def whole_lines
+      whole? ? lines : lines[0..-2]
+    end
+
+    def flush
+      whole? ? clear : @value = lines.last
+    end
+
+    def whole?
+      @value.end_with?($/)
+    end
+
+    def lines
+      @value.split($/).reject(&:empty?)
+    end
+
+    def clear
+      @value.clear
+    end
+  end
+end

test/models/tasks_test.rb

@@ -17,5 +17,18 @@ class TasksTest < ActiveSupport::TestCase
       task = shipit_tasks(:shipit_with_title_parsing_issue)
       assert_equal 'This task (title: Using the %{WRONG_VARIABLE_NAME}) cannot be shown due to an incorrect variable name. Check your shipit.yml file', task.title
     end
+
+    test "#write sends line-buffered output to task logger" do
+      task = shipit_tasks(:shipit)
+
+      mock_task_logger = mock.tap do |m|
+        m.expects(:info).with("hello").once
+        m.expects(:info).never
+      end
+
+      Shipit.stubs(:task_logger).returns(mock_task_logger)
+
+      task.write("hello\nworld")
+    end
   end
 end

test/unit/line_buffer_test.rb

@@ -0,0 +1,21 @@
+require 'test_helper'
+
+module Shipit
+  class LineBufferTest < ActiveSupport::TestCase
+    setup { @buffer = LineBuffer.new }
+
+    test "buffers partial lines" do
+      refute_predicate(@buffer.buffer("a"), :any?)
+      assert_equal(["a"], @buffer.buffer("\n").to_a)
+    end
+
+    test "splits up multiple lines" do
+      assert_equal(["a", "b"], @buffer.buffer("a\nb\n").to_a)
+    end
+
+    test "ignores blanks" do
+      refute_predicate(@buffer.buffer("\n\n\n"), :any?)
+      assert_equal(["a", "b"], @buffer.buffer("a\n\n\nb\n").to_a)
+    end
+  end
+end