How to differentiate build triggers in Jenkins Pipeline

The following code should works to determine if a user has started the pipeline or a timer/other trigger:

def isStartedByUser = currentBuild.rawBuild.getCause(hudson.model.Cause$UserIdCause) != null

The ability to get causes for a workflow run was released in version 2.22 (2018 Nov 02) to the Pipeline Supporting APIs Plugin. The feature was requested in JENKINS-41272.

A couple methods were added to the currentBuild global variable with that release:

getBuildCauses

• Returns a JSON array of build causes for the current build

EXPERIMENTAL - MAY CHANGE getBuildCauses(String causeClass)

• Takes a string representing the fully qualified Cause class and returns a JSON array of build causes filtered by that type for the current build, or an empty JSON array if no causes of the specified type apply to the current build

And an example from me submitting:

echo "${currentBuild.buildCauses}" // same as currentBuild.getBuildCauses()
echo "${currentBuild.getBuildCauses('hudson.model.Cause$UserCause')}"
echo "${currentBuild.getBuildCauses('hudson.triggers.TimerTrigger$TimerTriggerCause')}"

And the output:

[Pipeline] echo
[[_class:hudson.model.Cause$UserIdCause, shortDescription:Started by user anonymous, userId:null, userName:anonymous], [_class:org.jenkinsci.plugins.workflow.cps.replay.ReplayCause, shortDescription:Replayed #12]]
[Pipeline] echo
[]
[Pipeline] echo
[]
[Pipeline] End of Pipeline
Finished: SUCCESS

---

NOTE

There appears to be an issue with the currentBuild.getBuildCauses(type) when the type is a type of Cause contributed by a plugin. For example, currentBuild.getBuildCauses('org.jenkinsci.plugins.workflow.cps.replay.ReplayCause') fails with a java.lang.ClassNotFoundException. This was reported in JENKINS-54673 for the 2.22 version of the Pipeline: Supporting APIs (workflow-support) plugin. It is reportedly fixed in the 2.24 version.