title: How to read property from config file inside Jenkins pipeline using Config File Provider Plugin
body: <p>I want to parametrize my Jenkins pipeline with a simple properties config file </p>
  
  <pre><code>skip_tests=true
  </code></pre>
  
  <p>that I've added to Jenkins Config File Managment: </p>
  
  <p><a href="https://i.stack.imgur.com/ap707.png" rel="noreferrer"><img src="https://i.stack.imgur.com/ap707.png" alt="config file management screenshot"></a></p>
  
  <p>In my pipeline I'm importing this file and try to read from it using the Jenkins Pipeline Config File Plugin. </p>
  
  <pre><code>node('my-swarm') {
  
   MY_CONFIG = '27206b95-d69b-4494-a430-0a23483a6408'
  
   try {
  
       stage('prepare') {
           configFileProvider([configFile(fileId: "$MY_CONFIG", variable: 'skip_tests')]) {
               echo $skip_tests
               assert $skip_tests == 'true'
           }
       }
   } catch (Exception e) {
       currentBuild.result = 'FAILURE'
       print e
   }
  }
  </code></pre>
  
  <p>This results in an error:</p>
  
  <pre><code>provisioning config files...
  copy managed file [my.properties] to file:/home/jenkins/build/workspace/my-workspace@tmp/config7043792000148664559tmp
  [Pipeline] {
  [Pipeline] }
  Deleting 1 temporary files
  [Pipeline] // configFileProvider
  [Pipeline] }
  [Pipeline] // stage
  [Pipeline] echo
  groovy.lang.MissingPropertyException: No such property: $skip_tests for 
  class: groovy.lang.Binding
  </code></pre>
  
  <p>Any ideas what I'm doing wrong here?</p>