There is a hardcoded limit set in the admission code in the OpenShift API and Kubernetes, that causes the webhook to timeout after 13s.
The webhook has configuration (.webhooks[].timeoutSeconds) of a timeout in the webhook api object, however, if the value is higher than 13s, the apiserver will ignore it, and will timeout after 13 seconds. Basically the apiserver disregards the configuration and sets hardcoded 13s limit.

This is nowhere documented in the openshift docs and it creates a misunderstanding that if admin sets 30s as timeout, it will timeout after 13s -> without any explanation why.

https://github.com/openshift/kubernetes/blob/master/openshift-kube-apiserver/admission/admissionenablement/admission_config.go#L48

OpenShift Container Platform 4.10, 4.11, 4.12

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