Add the ability to use logfmt logging format.

AUTHORS.md

@@ -89,3 +89,4 @@ Resque Scheduler authors
 - sawanoboly
 - serek
 - iloveitaly
+- treacher

README.md

@@ -139,7 +139,7 @@ requiring `resque` and `resque/scheduler` (default empty).
 * `RESQUE_SCHEDULER_INTERVAL` - Interval in seconds for checking if a
 scheduled job must run (coerced with `Kernel#Float()`) (default `5`)
 * `LOGFILE` - Log file name (default empty, meaning `$stdout`)
-* `LOGFORMAT` - Log output format to use (either `'text'` or `'json'`,
+* `LOGFORMAT` - Log output format to use (either `'text'`, `'json'` or `'logfmt'`,
 default `'text'`)
 * `PIDFILE` - If non-empty, write process PID to file (default empty)
 * `QUIET` - Silence most output if non-empty (equivalent to a level of
@@ -663,7 +663,7 @@ are toggled by environment variables:
   - `QUIET` will stop logging anything. Completely silent.
   - `VERBOSE` opposite of 'QUIET'; will log even debug information
   - `LOGFILE` specifies the file to write logs to. (default standard output)
-  - `LOGFORMAT` specifies either "text" or "json" output format
+  - `LOGFORMAT` specifies either "text", "json" or "logfmt" output format
     (default "text")
 
 All of these variables are optional and will be given the following default

lib/resque/scheduler/configuration.rb

@@ -44,7 +44,7 @@ def logfile
         @logfile ||= environment['LOGFILE']
       end
 
-      # Sets whether to log in 'text' or 'json'
+      # Sets whether to log in 'text', 'json' or 'logfmt'
       attr_writer :logformat
 
       def logformat

lib/resque/scheduler/logger_builder.rb

@@ -15,7 +15,7 @@ class LoggerBuilder
       #   - :quiet if logger needs to be silent for all levels. Default - false
       #   - :verbose if there is a need in debug messages. Default - false
       #   - :log_dev to output logs into a desired file. Default - STDOUT
-      #   - :format log format, either 'text' or 'json'. Default - 'text'
+      #   - :format log format, either 'text', 'json' or 'logfmt'. Default - 'text'
       #
       # Example:
       #
@@ -67,6 +67,15 @@ def json_formatter
           ) + "\n"
         end
       end
+
+      def logfmt_formatter
+        proc do |severity, datetime, _progname, msg|
+          "Timestamp=\"#{datetime.iso8601}\" " \
+          "SeverityText=\"#{severity}\" " \
+          'InstrumentationScope="resque-scheduler" ' \
+          "Body=\"#{msg}\"\n"
+        end
+      end
     end
   end
 end

test/scheduler_setup_test.rb

@@ -139,4 +139,27 @@ def wipe
       assert $stdout.string =~ /: another thing/
     end
   end
+
+  context 'logger with logfmt formatter' do
+    setup do
+      nullify_logger
+      Resque::Scheduler.logformat = 'logfmt'
+      $stdout = StringIO.new
+    end
+
+    teardown do
+      $stdout = STDOUT
+    end
+
+    test 'logs with logfmt' do
+      Timecop.freeze do
+        Resque::Scheduler.log! 'another thing'
+
+        expected_output = "Timestamp=\"#{DateTime.now.iso8601}\" SeverityText=\"INFO\" " \
+                          "InstrumentationScope=\"resque-scheduler\" Body=\"another thing\"\n"
+
+        assert_equal $stdout.string, expected_output
+      end
+    end
+  end
 end