Kubernetes Container Probes
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External
- https://kubernetes.io/docs/tasks/configure-pod-container/configure-liveness-readiness-probes
- https://kubernetes.io/docs/concepts/workloads/pods/pod-lifecycle/#container-probes
Internal
Overview
Container Liveness Check
The result of the container liveness check is used by Kubernetes to know when to restart the container (Not the pod? How about atomicity?)
Container Readiness Check
The result of the container readiness check is used by Kubernetes to know when the container is ready to accept traffic. The pod is considered ready wen all of its containers are ready. The readiness check is used by services to decide whether to send traffic into the pod or not. Container will be removed from service endpoints if the probe fails.
Probe Template
kind: Pod spec: containers: - name: ... readinessProbe|livenessProbe: exec:
Example:
readinessProbe: exec: command: - /bin/sh - -c - nodetool status | grep -E "^UN\s+${POD_IP}" failureThreshold: 3 initialDelaySeconds: 90 periodSeconds: 30 successThreshold: 1 timeoutSeconds: 5