Passing non-string parameters to Jenkins JJB builder templates - jenkins

Question

I have a Jenkins JJB template, where I would like to customize triggers per job instance. This approach would have worked great if triggers was a string parameter, but it requires an object. How can I pass an object (in this case - an array) to the job template?
- job-template:
name: 'my-template-{proj}'
trigger_overrides: []
# The obj: syntax should have worked,
# but it doesn't handle the default from above
triggers: '{obj:trigger_overrides}'
- project:
name: my-project
jobs:
# for this job, customize triggers
- 'my-template':
proj: A
trigger_overrides:
- github
- timed: "#daily"
# this job should use the default triggers
- 'my-template':
proj: B
Note that in case triggers is always passed in, the empty triggers doesn't work. The global default overrides template parameter:
- defaults:
name: global
triggers:
- github
- job-template:
name: 'my-template-{proj}'
triggers: '{obj:trigger_overrides}'
- project:
name: my-project
jobs:
- 'my-template':
proj: A
trigger_overrides: []
Neither does this work (empty array is given as a default):
triggers: '{obj:trigger_overrides|[]}
P.S. This issue was also filed with jjb devs

Answer 1

You want to refer to how gerrit_release_trigger_file_paths is handled here in the releng/builder repository for passing a list:
https://github.com/opendaylight/releng-builder/blob/master/jjb/lf-infra/lf-infra-jobs.yaml#L120-L130
The original template is implemented in releng-global-jjb repository here: https://github.com/lfit/releng-global-jjb/blob/master/jjb/lf-docker-jobs.yaml#L229
JJB Best Practices:
https://docs.releng.linuxfoundation.org/projects/global-jjb/en/latest/best-practices.html
- project:
name: my-project
jobs:
- 'my-template':
proj: A
trigger_overrides:
- trigger_a
- trigger_b
- trigger_c