title: Is it possible to run cloud build using rest api with passing substitutions variables?
body: <p><br>
  I'm trying to run cloud build config.json using rest api.<br>
  I managed to run a simple config.json, but mine has substitution variable that I wish to pass and replace in my rest api request.<br>
  Is there a way to do so with rest api?
  I know it's possible with gcloud but I don't want to use it.<br></p>
  
  <p>Thanks!</p>