Most of these plugins are fairly old and inactive, but adding trigger compatibility will involve minimal code changes compared to other plugins. 

xTrigger-lib:

• update to be compatible with pipeline APIs
• Add unit tests to confirm changes are correct
• Bonus: speed up tests
  • Note: AbstractTriggerTest uses Thread.sleep(60000), possibly more efficient impl

FSTrigger (thanks Sam Van Oort):

• Implement EnvVars lookup that works for pipeline too (probably use a job or Jenkins level API)
• Check compatibility of xtrigger-lib and FSTriggerCause
• Create bridge methods for old method signatures & convert plugin signatures to new one
• Add test that can trigger with pipelines
• Manual test that file changes will trigger a pipeline build

URLtrigger:

• refactor to use pipeline compatible APIs
• Add unit tests that triggers pipeline build from url response change
• Manually test that a different response from a url will trigger a build

Build result trigger:

• Fix tests. errors after clone (I see slf4j in the stack trace ugh)
• refactor to use pipeline compatible APIs
  • More work than URL and FS trigger to refactor, lots of uses of AbstractProject 
• Add unit tests that triggers pipeline build from result
• Manually test that the build result of a job can trigger a pipeline job

Bonus:

• Clean up code and docs. Add READMEs
• addTrigger pipeline step

I don't think ScriptTrigger (security issue; no longer distributed) or IvyTrigger (only 250 downloads) are worth looking at.

From a user POV, I should be able to write a pipeline script like this:

pipeline {
    agent any
    triggers {
        fstrigger('/ant/glob/**')
    }
    stages {...}
}

I'm still using ScriptTrigger and would really appreciate if the new XTrigger plugin could support groovy scripts.

Provide a groovy function expected to return true/false, set a frequency (cron) and possibly restrict on which node to execute.

Then it should be possible to open the log of the last script execution and it's result from the project page.

Is the associated PR (https://github.com/jenkinsci/xtrigger-lib/pull/7) dead in the water? The last activity was back on Sep 24, 2017.

We'd really, really like to be able to leverage the URL Trigger plugin from within pipeline code. At present, we're having to stick freestyle jobs that use URL Trigger (watching specific paths in our Artifactory instance) in front of pipeline jobs, but it's pretty clunky and does not scale well.

I'm not trying to be pushy - just trying to determine if we need to give up hoping for this issue (really JENKINS-33691) to be resolved and start looking into other avenues.

New PRs available.  They were made small and independent to allow partial acceptance, such that, if one wasn't merged, a future PR wouldn't need to re-do all of the work (notice the similarities between #7 & #8).

• https://github.com/jenkinsci/xtrigger-lib/pull/11
• https://github.com/jenkinsci/xtrigger-lib/pull/12
• https://github.com/jenkinsci/xtrigger-lib/pull/13
• https://github.com/jenkinsci/xtrigger-lib/pull/14
• https://github.com/jenkinsci/xtrigger-lib/pull/15

It looks like all of the above pull requests have been merged. What's the next step for a downstream plugin like URL Trigger to get updated, such that there is support for pipeline jobs?

Kinldy fix this issue if possible or atleast provide some pointers how it can be implemented

Please, merge PRs from JENKINS-57078 with fixes from URL Trigger.