title: Sensu Reports `require': cannot load such file -- net/ping
body: <p>I have installed <code>sudo gem install net-ping</code> on 3 machines, same setup. But one server just refuses to accept that <code>net-ping</code> is installed. What am I missing ?</p>
  
  <p>I am trying to configure sensu that uses <code>check-ping.rb</code></p>
  
  <p>Here is what sensu reports</p>
  
  <pre><code>commandcheck-ping.rb -h &lt;IPAddress&gt; -C 0
  duration0.109
  executed2016-10-10 15:15:28
  interval20
  issued2016-10-10 15:15:28
  namecheck_ping_to_web_admin
  output/opt/sensu/embedded/lib/ruby/site_ruby/2.3.0/rubygems/core_ext/kernel_require.rb:55:in `require': cannot load such file -- net/ping (LoadError) from /opt/sensu/embedded/lib/ruby/site_ruby/2.3.0/rubygems/core_ext/kernel_require.rb:55:in `require' from /etc/sensu/plugins/check-ping.rb:30:in `&lt;main&gt;' 
  standalonetrue
  status3
  subscriberstest
  typestandard
  history3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3
  </code></pre>