How are the SCM changes determined on the Jenkins build screen?

Question

On the build screen in Jenkins it displays changes information which usually shows the SCM changes in the current build (in this case fetched from git). I am just wondering how the changes get populated. Does Jenkins compare the commits with the previous build or is it just a list of the latest commits?

In the image I get 'No changes' even though there were changes. I think this is because I did a shallow clone depth 1. See JENKINS-45586

Answer 1

Jenkins keeps local workspace for each job. After the first checkout, that workspace will be at certain SCM revision. Next time the job runs, it will compare local workspace revision to latest revision on server, and get a changelog that way.

Judging from your screenshot, your job was not started by changes to local workspace. Your job was started by SCM changes on an upstream build (FW_trunk_CI...). You need to examine the changelog on that job to see the SCM changes that triggered this.

If you want your downstream job (the one with this screenshot) to list changes from your upstream job (FW_trunk_CI), you need to add this plugin to the upstream job's "post-build" actions"