According to the Kubernetes documentation,
If the readiness probe fails, the endpoints controller removes the Pod's IP address from the endpoints of all Services that match the Pod.
So I understand that Kubernetes won't redirect requests to the pod when the readiness probe fails.
In addition, does Kubernetes kill the pod? Or does it keep calling the readiness probe until the response is successful?
Containers can use readiness probes to know whether the container being probed is ready to start receiving network traffic. If your container enters a state where it is still alive but cannot handle incoming network traffic (a common scenario during startup), you want the readiness probe to fail. That way, Kubernetes will not send network traffic to a container that isn't ready for it. If Kubernetes did prematurely send network traffic to the container, it could cause the load balancer (or router) to return a 502 error to the client and terminate the request; either that or the client would get a "connection refused" error message.
The name of the readiness probe conveys a semantic meaning. In effect, this probe answers the true-or-false question: "Is this container ready to receive network traffic?"
A readiness probe failing will not kill or restart the container.
A liveness probe sends a signal to Kubernetes that the container is either alive (passing) or dead (failing). If the container is alive, then Kubernetes does nothing because the current state is good. If the container is dead, then Kubernetes attempts to heal the application by restarting it.
The name liveness probe also expresses a semantic meaning. In effect, the probe answers the true-or-false question: "Is this container alive?"
A liveness probe failing will kill/restart a failed container.
Kubernetes has a newer probe called startup probes. This probe is useful for applications that are slow to start. It is a better alternative to increasing initialDelaySeconds on readiness or liveness probes. A startup probe allows an application to become ready, joined with readiness and liveness probes, it can increase the applications' availability.
Once the startup probe has succeeded once, the liveness probe takes over to provide a fast response to container deadlocks. If the startup probe never succeeds, the container is killed after failureThreshold * periodSeconds (the total startup timeout) and will be killed and restarted, subject to the pod's restartPolicy.
