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K8s L7 K8S 002 · 22 min

Analyzing a service failure where the Pod is Running but receives no traffic

A scenario for step-by-step checking of Service, Endpoint, readiness probe, and selector mismatch possibilities.

K8sPlatform ReliabilityLevel 7Pro22 min
Scenario

The new deployment is Running normally, but the Endpoint behind the service is empty, so real traffic is not delivered. The operator is looking only at the application because the pod is alive, but the selector and readiness probe conditions have drifted, so the Service path is cut off in the middle.

What to check first
  • Identify the primary failure signal in the Traffic Flow scenario.
  • Separate visible symptoms from the underlying technical dependency.
  • Describe the safest recovery path and the follow-up prevention work.
Checking checklist
  1. Summarize the current impact and the last known change.
  2. Collect direct evidence from logs, runtime state, and configuration before changing anything.
  3. Separate immediate recovery from permanent prevention work.
Recovery and prevention

Choose the smallest safe recovery action first, then record the prevention work that reduces repeat incidents.

Questions worth viewing together
Why can a healthy Service still route no traffic?

The Service object may exist, but selector mismatch, readiness failure, or empty Endpoints can leave it with no real backends.

What should be checked in order?

Validate selectors, Endpoint population, readiness state, and the namespace or label scope before chasing deeper network causes.