AKS 25 – Readiness and Liveness Probes

Readiness Probes – In Detail

Purpose and Function

Readiness probes determine if a container is ready to accept traffic. When a pod is not ready:

• The pod’s IP is removed from the endpoints list of all Services matching the pod
• Traffic is not routed to the pod until it passes readiness checks again
• The pod remains running but is effectively removed from service rotation

Liveness Probes – In Detail

Purpose and Function

Liveness probes determine if a container is running properly. When a pod fails liveness checks:

• The container is terminated and restarted according to the pod’s restart policy
• This helps recover from deadlocks, infinite loops, and other “stuck” states
• The container is forcibly restarted to resolve the issue

Key Differences Between Readiness and Liveness Probes

Aspect	Readiness Probe	Liveness Probe
Purpose	Determines if pod should receive traffic	Determines if pod should be restarted
Action on Failure	Remove pod from service endpoints	Terminate and restart container
Recovery Method	Pod remains running	Pod gets restarted
Use Case	Temporary failures, initialization	Permanent failures requiring restart
Configuration	Can have higher failure thresholds	Should have conservative thresholds
Timing	Check immediately after container starts	Delay until application fully initialized
Probe Endpoint	Often checks external dependencies	Typically checks internal application state
successThreshold	Can be > 1	Always 1 (must succeed once to transition to success)