https://logstash.wikimedia.org/goto/5a705b89015604f6d4a7e7827b8bad53
It looks like every ready probe against the main container is emitting a ProbeWarning message (excerpt from logstash below).
"k8s_event": { "firstTimestamp": "2021-10-19T16:49:50Z", "message": "Readiness probe warning: ", "reportingInstance": "", "reportingComponent": "", "reason": "ProbeWarning", "source": { "component": "kubelet", "host": "kubernetes1011.eqiad.wmnet" }, "type": "Warning", "metadata": { "resourceVersion": "114064680", "selfLink": "/api/v1/namespaces/toolhub/events/toolhub-main-779789d6fd-9bsw6.16af7c9a12f8b1ca", "name": "toolhub-main-779789d6fd-9bsw6.16af7c9a12f8b1ca", "creationTimestamp": "2021-10-19T16:49:50Z", "namespace": "toolhub", "uid": "b3e4b4be-703c-4a59-8a69-64bbff39f7d2" }, "eventTime": null, "lastTimestamp": "2021-10-21T22:44:30Z", "involvedObject": { "resourceVersion": "113229270", "name": "toolhub-main-779789d6fd-9bsw6", "fieldPath": "spec.containers{toolhub-main}", "kind": "Pod", "namespace": "toolhub", "uid": "1720e6cf-f986-4754-8680-7ef711247da1", "apiVersion": "v1" }, "count": 19409 },
Possibly related to this notice from the Kubernetes 1.14 release notes?
Health check (liveness & readiness) probes using an HTTPGetAction will no longer follow redirects to different hostnames from the original probe request. Instead, these non-local redirects will be treated as a Success (the documented behavior). In this case an event with reason "ProbeWarning" will be generated, indicating that the redirect was ignored. If you were previously relying on the redirect to run health checks against different endpoints, you will need to perform the healthcheck logic outside the Kubelet, for instance by proxying the external endpoint rather than redirecting to it. (#75416, @tallclair)