Creation of the ML Log Categorization job fails on a pristine 8.1.3 deployment with no hint

[cyrille-leclerc]

Elastic Cloud / Kibana / Elasticsearch version:

8.1.3

Describe the bug:

Creation of the ML Log Categorization job failed on a pristine 8.1.3 ESS deployment. I just have few logs in the .ds-logs-apm.app-default* indices.

Steps to reproduce:

1. Create a 8.1.3 deployment on ESS
2. Ingest few Otel logs (I did it using a Jenkins OpenTelemetry integration)
3. Navigation to Kibana / Logs / categorization and click on the button to create the ML job.

4. Wait for the creation of the ML job

5. A warning message reports: "Quality warning. While analyzing the log messages we've detected some problems which might indicate a reduced quality of the categorization results. Consider excluding the respective datasets from the analysis." with "Details: unknown"

6. Trying to recreate the ML job, I get:

Expected behavior:

Categorization ML job is created

Screenshots (if relevant):

Errors in browser console (if relevant):

Provide logs and/or server output (if relevant):

Any additional context:

[elasticmachine]

Pinging @elastic/infra-monitoring-ui (Team:Infra Monitoring UI)

[cyrille-leclerc]

As discussed with @vinaychandrasekhar , I associate this issue with the Actionable Observability team.

[weltenwort]

The quality warning surfaces the warning annotations added to the job by ML. @cyrille-leclerc the request to add these messages can be found in #59005.

The unknown category represents the "empty string" category that ML assigns when it can't assign a category to a partition.

[weltenwort]

as to why the text of the problem description for the "unknown" category is empty: this looks like a plain bug

[elasticmachine]

Pinging @elastic/obs-ux-logs-team (Team:obs-ux-logs)