How to add a custom health check in spring boot health?

Since Spring Boot 2.X

As stated by @yuranos87 the actuator concept has changed in Spring Boot 2.X but you can still add custom health checks easily by implementing HealthIndicator or for reactive applications ReactiveHealthIndicator:

@Component
public class CacheHealthIndicator implements HealthIndicator {

@Override
public Health health() {
    long result = checkSomething();
    if (result <= 0) {
        return Health.down().withDetail("Something Result", result).build();
    }
    return Health.up().build();      
  }
}

or

@Component
public class CacheHealthIndicator implements ReactiveHealthIndicator {

@Override
public Mono<Health> health() {
    return Mono.fromCallable(() -> checkSomething())
        .map(result -> {
            if (result <= 0) {
                return Health.down().withDetail("Something Result", result).build();
            }
            return Health.up().build();
        });
   }
}

Additionally you can add or extend any endpoint with @Endpointor @EndpointWebExtension. Endpoints here are info, health and many more. So you can add custom health check by using @Endpoint but it is much easier to do with HealthIndicator.

You can find more information about custom health checks and custom endpoints in the spring boot documentation.

Spring Boot 2.X has significantly changed actuator. A new, better mechanism to extend existing endpoints is enabled via @EndpointWebExtension.

That being said, health endpoint is a bit trickier to extend because one extension for it is provided out of the box by actuator itself. Without manipulating beans initialization process, your application will not be able to start since it will see 2 extensions and will not understand which one to choose. An easier way would be to use info instead and extend it:

@Component
@EndpointWebExtension(endpoint = InfoEndpoint.class)
public class InfoWebEndpointExtension {
   @Value("${info.build.version}")
   private String versionNumber;
   @Value("${git.commit.id}")
   private String gitCommit;
   @Value("${info.build.name}")
   private String applicationName;
   ...
   @ReadOperation
   public WebEndpointResponse<Map> info() {

Don't forget that you can also re-map URLs. In my case I prefer /status to /health and don't want /actuator/ in the path:

management.endpoints.web.base-path=/
management.endpoints.web.path-mapping.info=status

Another reason why I prefer /info is because I don't get this nested structure, which is default for /health:

{
"status": {
    "status": "ON",

If you want to have custom status message then You can check answer here - https://stackoverflow.com/a/66985769/4952800