title: passing a variable value from Jenkins to Node APP
body: <p>Not sure how to ask this question but would like to put it here and want to hear some suggestions.
  So far, I use "<code>DB_LINK"</code> variable that has mongo database url in my <code>config.json</code> file. My Node app uses this variable to connect to the Mongo. But this <code>DB_LINK</code> also gets checked into git, which we dont want this to happen because we dont want to check in the passwords into git.
  in my local development, I use local.json file that has all these configs and not check that file into git (in .gitignore entry). So it is fine making it work in my local dev environment, but the challenge is when Jenkins try to push the code to TEST, it has to pass testcases (it has to run test cases, so that time the <code>DB_LINK</code> value is needed) before deployment happens. so this is when I need this <code>DB_LINK</code> variable be passed from Jenkins. </p>
  
  <p>Here is what I did so far ..
  in Jenkins configurations, at the '<code>predefined parameters'</code> I added <code>DB_LINK=myMongoLink</code> to parameters list.
  but this value is not being handed over to my node app. Any suggestions on how to achieve what I am trying to achieve? </p>