istio.io/content/en/docs/reference/glossary/workload-instance-principal.md

title	test
Workload Instance Principal	n/a

The verifiable authority under which a workload instance runs. Istio's service-to-service authentication is used to produce the workload principal. By default workload principals are compliant with the SPIFFE ID format.

Workload instance principals are available in policy and telemetry configuration using the source.principal and destination.principal attributes.