title: Fluentd td-agent don't recognize custom plugin. Unknown input plugin
body: <p>I created a custom plugin called in_vCenterCrawler.rb and added it to the folder /etc/td-agent/plugin. In the file /etc/td-agent/td-agent.conf I have:</p>
  
  <pre><code>&lt;source&gt;
    @type vCenterCrawler #Also tried with in_vCenterCrawler
    port ****
    host '**.*.***.***'
    vCenterPort ***
    user "****"
    password "****"
  &lt;/source&gt;
  </code></pre>
  
  <p>When I run the command 'td-agent' I get the error:</p>
  
  <pre><code>config error file="/etc/td-agent/td-agent.conf" error="Unknown input plugin 'vCenterCrawler'. Run 'gem search -rd fluent-plugin' to find plugins
  </code></pre>
  
  <p>If I run 'gem search -rd fluent-plugin' I get:</p>
  
  <pre><code>The program 'gem' can be found in the following packages:
  * ruby
  * rubygems
  </code></pre>
  
  <p>But after finding the information in <a href="https://docs.fluentd.org/v0.12/articles/plugin-management" rel="nofollow noreferrer">https://docs.fluentd.org/v0.12/articles/plugin-management</a> I assumed I needed to transform my plugin into a gem, so I executed the command "td-agent-gem install vCenterCrawler" and I got:</p>
  
  <pre><code>ERROR:  Could not find a valid gem 'vCenterCrawler' (&gt;= 0) in any repository
  </code></pre>
  
  <p>At this point I'm confused and I don't know if this is a bug or if I'm missing something. I'm using td-agent 0.12.40.</p>
  
  <p>Thanks for any help.</p>