Fix Eureka health indicator when registry fetch fails

spring-cloud-netflix-eureka-client/src/main/java/org/springframework/cloud/netflix/eureka/EurekaHealthIndicator.java

@@ -73,11 +73,11 @@ private Status getStatus(Builder builder) {
 			long lastFetch = discoveryClient.getLastSuccessfulRegistryFetchTimePeriod();
 
 			if (lastFetch < 0) {
-				status = new Status("UP",
+				status = new Status("DOWN",
 						"Eureka discovery client has not yet successfully connected to a Eureka server");
 			}
 			else if (lastFetch > clientConfig.getRegistryFetchIntervalSeconds() * 2000) {
-				status = new Status("UP",
+				status = new Status("DOWN",
 						"Eureka discovery client is reporting failures to connect to a Eureka server");
 				builder.withDetail("renewalPeriod", instanceConfig.getLeaseRenewalIntervalInSeconds());
 				builder.withDetail("failCount", lastFetch / clientConfig.getRegistryFetchIntervalSeconds());

spring-cloud-netflix-eureka-client/src/test/java/org/springframework/cloud/netflix/eureka/EurekaHealthIndicatorTests.java

@@ -0,0 +1,84 @@
+/*
+ * Copyright 2026-present the original author or authors.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      https://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package org.springframework.cloud.netflix.eureka;
+
+import com.netflix.appinfo.EurekaInstanceConfig;
+import com.netflix.appinfo.InstanceInfo;
+import com.netflix.discovery.DiscoveryClient;
+import com.netflix.discovery.EurekaClientConfig;
+import com.netflix.discovery.shared.Applications;
+import org.junit.jupiter.api.Test;
+import org.junit.jupiter.api.extension.ExtendWith;
+import org.mockito.Mock;
+import org.mockito.junit.jupiter.MockitoExtension;
+
+import org.springframework.boot.health.contributor.Health;
+import org.springframework.boot.health.contributor.Status;
+
+import static org.assertj.core.api.Assertions.assertThat;
+import static org.mockito.Mockito.when;
+
+/**
+ * Tests for {@link EurekaHealthIndicator}.
+ *
+ * @author Lucas Ma
+ */
+@ExtendWith(MockitoExtension.class)
+class EurekaHealthIndicatorTests {
+
+	@Mock
+	private DiscoveryClient eurekaClient;
+
+	@Mock
+	private EurekaInstanceConfig instanceConfig;
+
+	@Mock
+	private EurekaClientConfig clientConfig;
+
+	@Test
+	void reportsDownWhenRegistryHasNeverBeenFetched() {
+		when(this.eurekaClient.getInstanceRemoteStatus()).thenReturn(InstanceInfo.InstanceStatus.UP);
+		when(this.eurekaClient.getLastSuccessfulRegistryFetchTimePeriod()).thenReturn(-1L);
+		when(this.eurekaClient.getApplications()).thenReturn(new Applications());
+		when(this.clientConfig.shouldFetchRegistry()).thenReturn(true);
+
+		Health health = healthIndicator().health();
+
+		assertThat(health.getStatus()).isEqualTo(Status.DOWN);
+	}
+
+	@Test
+	void reportsDownWhenRegistryFetchIsStale() {
+		when(this.eurekaClient.getInstanceRemoteStatus()).thenReturn(InstanceInfo.InstanceStatus.UP);
+		when(this.eurekaClient.getLastSuccessfulRegistryFetchTimePeriod()).thenReturn(61_000L);
+		when(this.eurekaClient.getApplications()).thenReturn(new Applications());
+		when(this.clientConfig.shouldFetchRegistry()).thenReturn(true);
+		when(this.clientConfig.getRegistryFetchIntervalSeconds()).thenReturn(30);
+		when(this.instanceConfig.getLeaseRenewalIntervalInSeconds()).thenReturn(30);
+
+		Health health = healthIndicator().health();
+
+		assertThat(health.getStatus()).isEqualTo(Status.DOWN);
+		assertThat(health.getDetails()).containsEntry("renewalPeriod", 30);
+		assertThat(health.getDetails()).containsEntry("failCount", 2033L);
+	}
+
+	private EurekaHealthIndicator healthIndicator() {
+		return new EurekaHealthIndicator(this.eurekaClient, this.instanceConfig, this.clientConfig);
+	}
+
+}