Script for checking BackgroundJob activity, suitable for Cron or Nagios

check_bj_activity.rb

#!/usr/bin/env ruby

# Crontab example:
# 55 * * * * (cd $HOME/rails-app/current ; ./script/check_bj_activity.rb >/dev/null)

TEST_SQL = <<-SQL
SELECT COUNT(*) FROM bj_job WHERE state = 'finished' 
  AND finished_at > DATE_SUB(UTC_TIMESTAMP(), INTERVAL 1 HOUR)
SQL

begin
  require File.dirname(__FILE__) + '/../config/boot'
  require File.dirname(__FILE__) + '/../config/environment'

  recent_jobs = ActiveRecord::Base.connection.select_value(TEST_SQL).to_i
rescue Exception => e
  STDERR.puts "ERROR: #{e.class.to_s} - #{e.to_s}"
  Kernel.exit(3)
end

if recent_jobs > 0
  STDOUT.puts "Found #{recent_jobs} finished jobs in the last hour"
  Kernel.exit(0)
else
  STDERR.puts "WARNING: No jobs finished in the last hour!"
  Kernel.exit(1)
end