CODEWITHSUNDEEP
spring-boothealth-monitoring
ddekany
ddekany

Reputation: 31122

OUT_OF_SERVICE VS DOWN health status (Spring Boot)

I couldn't find it documented anywhere... when to use which?

My wild guess is that Status.OUT_OF_SERVICE means that the service is deliberately shut down, while Status.DOWN means that the service is unhealthy (not necessarily unavailable, it just should be looked at).

Upvotes: 3

Views: 7434

Answers (3)

mipo256
mipo256

Reputation: 3150

Your guess is a bit incorrect. Both DOWN and OUT_OF_SERVICE are statuses of the various components in spring actuator realm. In simple terms:

  • DOWN means that the component is unavailble
  • OUT_OF_SERVICE means that the component is not yet ready

Use whatever status makes sense in your case, but in general both of these statuses will return 503 to the http callee by default. So the difference is mainly for description purposes.

For debuggers out there - out of my own experiance, I will say that most of the time in spring boot itself you will expriance the OUT_OF_SERVICE status becuase of the readinessState probe. In order to check it and verify the source of the problem you can set this property:

management.endpoint.health.show-details=always

Or you can request the readinessState prob directly via /actuator/health/readiness, but I'd prefer the first approach since it provides a lot of debugging info so you will identify the cause sooner.

P.S: If the readiness probe is in the OUT_OF_SERVICE state, then you need to check that all of your synchronous:

  • EventListener-s
  • ApplicationRunner-s
  • CommandLineRunner-s etc

are finished successfuly. If any of them block the current thread, then spring will consider that the application is not yet ready, and will constantly return OUT_OF_SERVICE for readinessProbe until thread is released.

Upvotes: 0

Thomas Marti
Thomas Marti

Reputation: 940

If believe the Javadoc for org.springframework.boot.actuate.health.Status answers this:

(Although I also think the documentation in this area could be improved with some examples.)

/**
 * {@link Status} indicating that the component or subsystem has suffered an
 * unexpected failure.
 */
public static final Status DOWN = new Status("DOWN");

/**
 * {@link Status} indicating that the component or subsystem has been taken out of
 * service and should not be used.
 */
public static final Status OUT_OF_SERVICE = new Status("OUT_OF_SERVICE");

As you correctly guessed, DOWN is unexpected downtime whereas OUT_OF_SERVICE means a service was deliberately shut down.

Upvotes: 0

jst
jst

Reputation: 1747

The docs http://docs.spring.io/spring-boot/docs/current/reference/htmlsingle/#_writing_custom_healthindicators give an example of a custom order severity. The default OrderedHealthAggregator uses an order like this

Status.DOWN, Status.OUT_OF_SERVICE, Status.UP, Status.UNKNOWN

So spring boot considers DOWN more "severe" than OUT_OF_SERVICE. By default both map to HTTP 503 Service Unavailable for the /health endpoint. So really out of the box if you use either you will see the same behavior. None of the spring provided health indicators use OUT_OF_SERVICE. They just use DOWN.

Upvotes: 2

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