Endpoint for applications list in UHS (not YK) returns 'null' when UHS db shows many apps

[richscott]

When UHS collects applications from YK, the UHS database does have those entries, however the /api/v1/partition/:partition/queue/:queue/applications just returns null.

To reproduce, go to a copy of the UHS repo:

$ make kind-all
$ make run

Then submit the attached jobs file:

$ kubectl apply -f denis-jobs.yml

(This is just a regular decent-sized list of jobs to submit to Yunikorn - you can use most any other job submission file).
Verify that the Yunikorn web UI shows the applications are queued and/or running, by visiting http://localhost:30001/#/dashboard in your browser.z

Optionally, you can also check the UHS database, by running a postgresql psql client in the cluster, e.g.

$ kubectl run postgresql-client --rm --tty -i --restart='Never' --namespace yunikorn --image docker.io/bitnami/postgresql:17.2.0-debian-12-r1 --env="PGPASSWORD=psw" --command -- psql --host postgresql -U postgres -d uhs -p 5432
uhs=# select count(*) from applications;
81
\q
$

The actual bug is in the applications endpoint on UHS - query it by doing:

$curl  http://localhost:8989/api/v1/partition/default/queue/root/applications
null
$

This should instead return a large JSON list of the applications that UHS detected from YK.

[sudiptob2]

Thank you for providing detailed information on the ticket!

After further investigation, I identified the root cause of the issue:

1. The URL used to fetch applications is slightly incorrect. The correct URL should include partition_id and queue_id instead of partition_name and queue_name.
   Example:
   curl http://localhost:8989/api/v1/partition/01JE4M3K3KK3ZB2JPVH6A28B0F/queue/01JE4M3K3K5FF5WY2J4YWKTMXA/applications

2. The queue_id is not included in the YuniKorn-Core response, so it is always stored as null in the queue_id field of the application table. Consequently, even if the correct ID parameters are provided, the query will still return null.
   Reference: YuniKorn-Core Code (Lines 335–339)

Solution: Added queueID in yunikorn core. After this PR is merged we should get desired result in the application endpoint.
PR: G-Research/yunikorn-core#11