git describe --tags does not work on Jenkins pipeline build

Question

I've seen this question which goes in a similar direction but not quite. The problem there was that the tags were simply not pushed correctly.

I am currently using Jenkins to build my python projects using setuptools_scm, which basically uses git describe to get a (more or less) sensible version number, even if not on a tag. The pipeline is defined using a seed job in JobDSL like this (abbreviated to get to the main points):

import BuildProjects

BuildProjects.build_projects.each { def bproject ->
   multibranchPipelineJob("tool/${bproject}") {
      branchSources {
         branchSource {
            source {
               git {
                  id('tool_${bproject}')
                  remote("${BuildProjects.scmBaseLocation}/${bproject}.git")
                  credentialsId(BuildProjects.scmUser)
                  traits {
                     gitBranchDiscovery()
                     gitTagDiscovery()
                     cloneOptionTrait {
                        extension {
                           shallow(false)
                           noTags(false)
                           reference('grmblwrx')
                           timeout(1)
                        }
                     }
                  }
               }
            }
         }
      }

   }
}

Some configuration values are taken from BuildProjects.

When running jenkins, I see that it fetches tags:

 > git fetch --tags --progress -- ssh://git@git.my-company.net/tools.git +refs/heads/*:refs/remotes/origin/* # timeout=1

and in fact, I can see the tags when I output them in my Jenkinsfile using an

sh "git tag"

block. But using

sh "git describe --tags"

gives

fatal: No tags can describe '<Commit hash>'.
Try --always, or create some tags.

I read somewhere that this might be due to a sparse checkout: The commits between the tag and the current HEAD might be missing. Upon closer inspection, I found in my logs

> git config core.sparsecheckout # timeout=10
> git checkout -f <Commit hash> # timeout=10

right after the git fetch line shown above. It seems that somehow my configuration in the JobDSL is not respected. Any ideas?

Answer 1

Since I posted my question, we updated our Jenkins instance and some plugins, especially the git plugin. For some reason, it "simply works" now. I cannot reproduce the old setting without a lot of trouble, so I cannot easily figure out what caused the "fix".