New option to trigger alert on failed restarts

Current versions of puppet treat resources that failed to restart as different
kind of failures and they are not necessarily reported, there is puppet bug
PUP-2280 that explains it in more detail. Until it is fixed in version 5 of
puppet it would be useful to see such failures in monitoring, so I added option
to report this failure. Option is by default off to not change usual behavior.

CHANGELOG.md

@@ -4,6 +4,8 @@ This project adheres to [Semantic Versioning](http://semver.org/).
 This CHANGELOG follows the format listed at [Keep A Changelog](http://keepachangelog.com/)
 
 ## [Unreleased]
+### Added
+- `check-puppet-last-run.rb`: Added option for reporting failed restarts (@antonidabek)
 
 ## [1.1.0] - 2017-01-30
 ### Added

bin/check-puppet-last-run.rb

@@ -59,6 +59,13 @@ class PuppetLastRun < Sensu::Plugin::Check::CLI
          default:     '/opt/puppetlabs/puppet/cache/state/agent_disabled.lock',
          description: 'Path to agent disabled lock file'
 
+  option :report_restart_failures,
+         short:       '-r',
+         long:        '--report-restart-failures',
+         boolean:     true,
+         default:     false,
+         description: 'Raise alerts if restart failures have happened'
+
   def run
     unless File.exist?(config[:summary_file])
       unknown "File #{config[:summary_file]} not found"
@@ -78,6 +85,11 @@ def run
       else
         critical "#{config[:summary_file]} is missing information about the events"
       end
+      @restart_failures = if config[:report_restart_failures] && summary['resources']
+                            summary['resources']['failed_to_restart'].to_i
+                          else
+                            0
+                          end
     rescue
       unknown "Could not process #{config[:summary_file]}"
     end
@@ -95,7 +107,11 @@ def run
       @message += " with #{@failures} failures"
     end
 
-    if @now - @last_run > config[:crit_age] || @failures > 0
+    if @restart_failures > 0
+      @message += " with #{@restart_failures} restart failures"
+    end
+
+    if @now - @last_run > config[:crit_age] || @failures > 0 || @restart_failures > 0
       critical @message
     elsif @now - @last_run > config[:warn_age]
       warning @message