Support setting custom port for LB health-checks. (#1039)

docs/src/main/asciidoc/spring-cloud-commons.adoc

@@ -979,7 +979,7 @@ TIP: The `HealthCheckServiceInstanceListSupplier` relies on having updated insta
 `HealthCheckServiceInstanceListSupplier` uses properties prefixed with
 `spring.cloud.loadbalancer.health-check`. You can set the `initialDelay` and `interval`
 for the scheduler. You can set the default path for the healthcheck URL by setting
-the value of the `spring.cloud.loadbalancer.health-check.path.default` property. You can also set a specific value for any given service by setting the value of the `spring.cloud.loadbalancer.health-check.path.[SERVICE_ID]` property, substituting `[SERVICE_ID]` with the correct ID of your service. If the `[SERVICE_ID]` is not specified, `/actuator/health` is used by default.  If the `[SERVICE_ID]` is set to `null` or empty as a value, then the health check will not be executed.
+the value of the `spring.cloud.loadbalancer.health-check.path.default` property. You can also set a specific value for any given service by setting the value of the `spring.cloud.loadbalancer.health-check.path.[SERVICE_ID]` property, substituting `[SERVICE_ID]` with the correct ID of your service. If the `[SERVICE_ID]` is not specified, `/actuator/health` is used by default.  If the `[SERVICE_ID]` is set to `null` or empty as a value, then the health check will not be executed. You can also set a custom port for health-check requests by setting the value of `spring.cloud.loadbalancer.health-check.port`. If none is set, the port under which the requested service is available at the service instance.
 
 TIP: If you rely on the default path (`/actuator/health`), make sure you add `spring-boot-starter-actuator` to your collaborator's dependencies, unless you are planning to add such an endpoint on your own.
 

spring-cloud-commons/src/main/java/org/springframework/cloud/client/loadbalancer/LoadBalancerProperties.java

@@ -186,8 +186,19 @@ public class LoadBalancerProperties {
 		 */
 		private Duration refetchInstancesInterval = Duration.ofSeconds(25);
 
+		/**
+		 * Path at which the health-check request should be made. Can be set up per
+		 * <code>serviceId</code>. A <code>default</code> value can be set up as well. If
+		 * none is set up, <code>/actuator/health</code> will be used.
+		 */
 		private Map<String, String> path = new LinkedCaseInsensitiveMap<>();
 
+		/**
+		 * Path at which the health-check request should be made. If none is set, the port
+		 * under which the requested service is available at the service instance.
+		 */
+		private Integer port;
+
 		/**
 		 * Indicates whether the instances should be refetched by the
 		 * <code>HealthCheckServiceInstanceListSupplier</code>. This can be used if the
@@ -251,6 +262,14 @@ public class LoadBalancerProperties {
 			this.interval = interval;
 		}
 
+		public Integer getPort() {
+			return port;
+		}
+
+		public void setPort(Integer port) {
+			this.port = port;
+		}
+
 	}
 
 	public static class Retry {

spring-cloud-loadbalancer/src/main/java/org/springframework/cloud/loadbalancer/core/HealthCheckServiceInstanceListSupplier.java

@@ -30,6 +30,7 @@ import reactor.retry.Repeat;
 
 import org.springframework.beans.factory.DisposableBean;
 import org.springframework.beans.factory.InitializingBean;
+import org.springframework.cloud.client.DefaultServiceInstance;
 import org.springframework.cloud.client.ServiceInstance;
 import org.springframework.cloud.client.loadbalancer.LoadBalancerProperties;
 import org.springframework.cloud.client.loadbalancer.reactive.ReactiveLoadBalancer;
@@ -156,7 +157,7 @@ public class HealthCheckServiceInstanceListSupplier extends DelegatingServiceIns
 			return Mono.just(true);
 		}
 		String healthCheckPath = healthCheckPropertyValue != null ? healthCheckPropertyValue : defaultHealthCheckPath;
-		return aliveFunction.apply(serviceInstance, healthCheckPath);
+		return aliveFunction.apply(updatedServiceInstance(serviceInstance), healthCheckPath);
 	}
 
 	@Override
@@ -167,4 +168,14 @@ public class HealthCheckServiceInstanceListSupplier extends DelegatingServiceIns
 		}
 	}
 
+	private ServiceInstance updatedServiceInstance(ServiceInstance serviceInstance) {
+		Integer healthCheckPort = healthCheck.getPort();
+		if (serviceInstance instanceof DefaultServiceInstance && healthCheckPort != null) {
+			return new DefaultServiceInstance(serviceInstance.getInstanceId(), serviceInstance.getServiceId(),
+					serviceInstance.getHost(), healthCheckPort, serviceInstance.isSecure(),
+					serviceInstance.getMetadata());
+		}
+		return serviceInstance;
+	}
+
 }

spring-cloud-loadbalancer/src/test/java/org/springframework/cloud/loadbalancer/core/HealthCheckServiceInstanceListSupplierTests.java

@@ -41,6 +41,7 @@ import org.springframework.boot.web.server.LocalServerPort;
 import org.springframework.cloud.client.DefaultServiceInstance;
 import org.springframework.cloud.client.ServiceInstance;
 import org.springframework.cloud.client.loadbalancer.LoadBalancerProperties;
+import org.springframework.cloud.loadbalancer.support.LoadBalancerClientFactory;
 import org.springframework.cloud.loadbalancer.support.ServiceInstanceListSuppliers;
 import org.springframework.context.annotation.Configuration;
 import org.springframework.web.bind.annotation.GetMapping;
@@ -50,6 +51,7 @@ import org.springframework.web.client.RestTemplate;
 import org.springframework.web.reactive.function.client.WebClient;
 
 import static org.assertj.core.api.Assertions.assertThat;
+import static org.assertj.core.api.Assertions.catchThrowable;
 import static org.mockito.ArgumentMatchers.any;
 import static org.mockito.Mockito.mock;
 import static org.mockito.Mockito.never;
@@ -579,6 +581,27 @@ class HealthCheckServiceInstanceListSupplierTests {
 		assertThat(alive).isTrue();
 	}
 
+	@Test
+	void shouldCheckUseProvidedPortForHealthCheckRequest() {
+		Throwable exception = catchThrowable(() -> {
+			String serviceId = "ignored-service";
+			healthCheck.setPort(8888);
+			LoadBalancerProperties properties = new LoadBalancerProperties();
+			properties.setHealthCheck(healthCheck);
+			LoadBalancerClientFactory loadBalancerClientFactory = mock(LoadBalancerClientFactory.class);
+			when(loadBalancerClientFactory.getProperties(serviceId)).thenReturn(properties);
+			ServiceInstance serviceInstance = new DefaultServiceInstance("ignored-service-1", serviceId, "127.0.0.1",
+					port, false);
+			listSupplier = new HealthCheckServiceInstanceListSupplier(
+					ServiceInstanceListSuppliers.from(serviceId, serviceInstance), loadBalancerClientFactory,
+					healthCheckFunction(webClient));
+
+			listSupplier.isAlive(serviceInstance).block();
+		});
+
+		assertThat(exception).hasMessageContaining("Connection refused: /127.0.0.1:888");
+	}
+
 	@Configuration(proxyBeanMethods = false)
 	@EnableAutoConfiguration
 	@RestController