How to make sure list of parameters are updated before running a Jenkins pipeline?

Question

A Jenkins pipeline project is configured to fetch its Jenkinsfile from a Git repo:

If I change the list of parameters, for example, from:

properties([         parameters([                 string(name: 'FOO', description: 'Choose foo')         ]) ]) 

to:

properties([         parameters([                 string(name: 'FOO', description: 'Choose foo'),                 string(name: 'BAR', description: 'Choose bar')         ]) ]) 

And run the build, the first run does not show the newly added BAR parameter:

As the updated Jenkins file expects the BAR parameter to be present, this causes the first build after the change to fail as the user is not presented with an input to enter this value.

Is there a way to prevent this? To make sure the Jenkinsfile is up-to-date before showing the parameter entry page?

Answer 1

Short answer: No. It would be nice if there was some facility for parsing and processing the Jenkinsfile separate from the build, but there's not.

Jenkins does not know about the new parameters until it retrieves, parses, and runs the Jenkinsfile, and the only way to do that is to...run a build.

In effect, the build history will always be "one run behind" the Jenkinsfile; when you change something in the Jenkinsfile, the next build will run with the "old" Jenkinsfile, but pick up and process the new Jenkinsfile for the build after that.