[YUNIKORN-2369] Using unique generated Application IDs breaks scheduling

• Type: Bug
• Status: Closed
• Priority: Critical
• Resolution: Fixed
• Fix Version/s: 1.5.0
• Component/s: shim - kubernetes
• Labels: pull-request-available
• Target Version: 1.5.0
• Assignee: Craig Condit
• Reporter: Craig Condit
• Created: 29/Jan/24 16:37
• Updated: 20/Mar/24 14:32
• Resolved: 31/Jan/24 22:39

Description

YUNIKORN-1273 added support to create unique application IDs instead of grouping pods within a given namespace into a single application. However, using this feature in combination with the YuniKorn admission controller results in a failure to accept pods, as the pod UID (used in the generated identifier) has not yet been created when admission controllers run.

For example, given a pod UID of deadbeefcafe running in namespace test, the expected application ID is test-deadbeefcafe. However, since the pod UID is not present when the admission controller runs, this evaluates to `test-` and results in the pod being rejected by Kubernetes since labels must contain only alphanumeric characters and "-", and must start end end with alphanumeric characters.

One way to solve this would be to set the applicationId label in the admission controller to something like test-uniqueautogen and then have the scheduler interpret the presence of the -uniqueautogen suffix as a request to use the pod UID as part of the name (since it will be available to the scheduler). This satisfies the original design of YUNIKORN-1273, which was to make the identifiers predictable (since they contain the pod UID), unique (as they still are UUIDs) and consistent between restarts of the scheduler. A drawback to this approach is that the applicationId label will not reflect the real applicationId used.

Issue Links

• breaks: YUNIKORN-1856 Pod creation fails in certain cases when generateUniqueAppId is enabled
• is caused by: YUNIKORN-2082 Make unique applicationIDs generated by YUNIKORN-1273 be reproducible
• is duplicated by: YUNIKORN-2332 admissionController.filtering.generateUniqueAppId not work as expected
• is related to: YUNIKORN-1273 Add option to have unique application ids in a namespace
• links to: GitHub Pull Request #773