Spring Boot Actuator Probes and Kubernetes

This document explains how Spring Boot Actuator health endpoints (/actuator/health/readiness and /actuator/health/liveness) interact with Kubernetes probes (readinessProbe, livenessProbe, and startupProbe).

Do Actuator endpoints return objects?

Yes, Spring Boot Actuator health endpoints return JSON objects.

Example of a successful response:

{
  "status": "UP",
  "components": {
    "livenessState": {
      "status": "UP"
    }
  }
}

Are these object values checked in Kubernetes?

No, Kubernetes (via httpGet probes) does not parse or check the values inside the JSON object.

Instead, Kubernetes relies on the HTTP Response Status Code:

Success: Any status code >= 200 and < 400 (e.g., 200 OK) is considered a pass.
Failure: Any other status code (e.g., 503 Service Unavailable or 500 Internal Server Error) is considered a failure.

How it works together

The integration works because Spring Boot is configured to map its internal health state to HTTP status codes:

Configuration: In application.yml, probes are enabled:
management: endpoint: health: probes: enabled: true health: livenessstate: enabled: true readinessstate: enabled: true
Mapping:
- Internal state UP maps to HTTP 200.
- Internal state DOWN or OUT_OF_SERVICE maps to HTTP 503.
Probing: Kubernetes performs the HTTP request.
- A 200 OK confirms health.
- A 503 Service Unavailable triggers failure logic (e.g., container restart or removal from service load balancer).

Summary

Kubernetes checks the HTTP status code, which Spring Boot Actuator manages based on internal application health. The JSON response is intended for observability and monitoring tools, not for Kubernetes' native probing mechanism.

Last modified: 05 April 2026