Fix 1831

spring-cloud-kubernetes-commons/src/main/java/org/springframework/cloud/kubernetes/commons/config/ConfigUtils.java

@@ -339,10 +339,11 @@ public static <T> void registerSingle(ConfigurableBootstrapContext bootstrapCont
 			String name, ApplicationListener<?> listener) {
 		bootstrapContext.registerIfAbsent(cls, BootstrapRegistry.InstanceSupplier.of(instance));
 		bootstrapContext.addCloseListener(event -> {
-			if (event.getApplicationContext().getBeanFactory().getSingleton(name) == null) {
-				event.getApplicationContext()
-					.getBeanFactory()
-					.registerSingleton(name, event.getBootstrapContext().get(cls));
+
+			T singleton = event.getBootstrapContext().get(cls);
+
+			if (event.getApplicationContext().getBeanFactory().getSingleton(name) == null && singleton != null) {
+				event.getApplicationContext().getBeanFactory().registerSingleton(name, singleton);
 				event.getApplicationContext().addApplicationListener(listener);
 			}
 		});

spring-cloud-kubernetes-commons/src/main/java/org/springframework/cloud/kubernetes/commons/config/KubernetesConfigDataLocationResolver.java

@@ -52,6 +52,8 @@
 public abstract class KubernetesConfigDataLocationResolver
 		implements ConfigDataLocationResolver<KubernetesConfigDataResource>, Ordered {
 
+	private static final Class<KubernetesClientProperties> PROPERTIES_CLASS = KubernetesClientProperties.class;
+
 	private static final boolean RETRY_IS_PRESENT = isPresent("org.springframework.retry.annotation.Retryable", null);
 
 	private final Log log;
@@ -139,8 +141,7 @@ private void registerProperties(ConfigDataLocationResolverContext resolverContex
 			SecretsConfigProperties secretsProperties) {
 
 		ConfigurableBootstrapContext bootstrapContext = resolverContext.getBootstrapContext();
-		registerSingle(bootstrapContext, KubernetesClientProperties.class, clientProperties,
-				"configDataKubernetesClientProperties");
+		registerSingle(bootstrapContext, PROPERTIES_CLASS, clientProperties, "configDataKubernetesClientProperties");
 
 		if (configMapProperties != null) {
 			registerSingle(bootstrapContext, ConfigMapConfigProperties.class, configMapProperties,
@@ -174,15 +175,14 @@ private static PropertyHolder of(ConfigDataLocationResolverContext context) {
 		private static KubernetesClientProperties clientProperties(ConfigDataLocationResolverContext context,
 				String namespace) {
 			KubernetesClientProperties kubernetesClientProperties;
+			ConfigurableBootstrapContext bootstrapContext = context.getBootstrapContext();
 
-			if (context.getBootstrapContext().isRegistered(KubernetesClientProperties.class)) {
-				kubernetesClientProperties = context.getBootstrapContext()
-					.get(KubernetesClientProperties.class)
-					.withNamespace(namespace);
+			if (bootstrapContext.isRegistered(PROPERTIES_CLASS) && bootstrapContext.get(PROPERTIES_CLASS) != null) {
+				kubernetesClientProperties = bootstrapContext.get(PROPERTIES_CLASS).withNamespace(namespace);
 			}
 			else {
 				kubernetesClientProperties = context.getBinder()
-					.bindOrCreate(KubernetesClientProperties.PREFIX, Bindable.of(KubernetesClientProperties.class))
+					.bindOrCreate(KubernetesClientProperties.PREFIX, Bindable.of(PROPERTIES_CLASS))
 					.withNamespace(namespace);
 			}
 

spring-cloud-kubernetes-fabric8-discovery/src/test/java/org/springframework/cloud/kubernetes/DummyConfigDataLocationResolver.java

@@ -0,0 +1,43 @@
+/*
+ * Copyright 2013-2025 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.kubernetes;
+
+import org.springframework.boot.autoconfigure.condition.ConditionalOnProperty;
+import org.springframework.boot.context.config.ConfigDataLocation;
+import org.springframework.boot.context.config.ConfigDataLocationResolverContext;
+import org.springframework.boot.context.config.Profiles;
+import org.springframework.boot.logging.DeferredLogFactory;
+import org.springframework.cloud.kubernetes.commons.KubernetesNamespaceProvider;
+import org.springframework.cloud.kubernetes.commons.config.KubernetesConfigDataLocationResolver;
+
+/**
+ * @author wind57
+ */
+@ConditionalOnProperty(value = "dummy.config.loader.enabled", havingValue = "true", matchIfMissing = false)
+class DummyConfigDataLocationResolver extends KubernetesConfigDataLocationResolver {
+
+	DummyConfigDataLocationResolver(DeferredLogFactory factory) {
+		super(factory);
+	}
+
+	@Override
+	protected void registerBeans(ConfigDataLocationResolverContext resolverContext, ConfigDataLocation location,
+			Profiles profiles, PropertyHolder propertyHolder, KubernetesNamespaceProvider namespaceProvider) {
+
+	}
+
+}

spring-cloud-kubernetes-fabric8-discovery/src/test/java/org/springframework/cloud/kubernetes/fabric8/discovery/Fabric8ConfigServerTest.java

@@ -0,0 +1,78 @@
+/*
+ * Copyright 2013-2025 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.kubernetes.fabric8.discovery;
+
+import com.github.tomakehurst.wiremock.WireMockServer;
+import com.github.tomakehurst.wiremock.client.WireMock;
+import org.assertj.core.api.Assertions;
+import org.junit.jupiter.api.AfterAll;
+import org.junit.jupiter.api.BeforeAll;
+import org.junit.jupiter.api.Test;
+
+import org.springframework.beans.factory.annotation.Autowired;
+import org.springframework.boot.autoconfigure.SpringBootApplication;
+import org.springframework.boot.test.context.SpringBootTest;
+import org.springframework.context.ApplicationContext;
+
+import static com.github.tomakehurst.wiremock.client.WireMock.aResponse;
+import static com.github.tomakehurst.wiremock.client.WireMock.get;
+import static com.github.tomakehurst.wiremock.client.WireMock.stubFor;
+import static com.github.tomakehurst.wiremock.client.WireMock.urlEqualTo;
+import static com.github.tomakehurst.wiremock.core.WireMockConfiguration.options;
+
+/**
+ * Test that proves that this
+ * <a href="https://github.com/spring-cloud/spring-cloud-kubernetes/issues/1831">issue</a>
+ * is fixed.
+ *
+ * @author wind57
+ */
+@SpringBootTest(webEnvironment = SpringBootTest.WebEnvironment.RANDOM_PORT,
+		properties = { "spring.main.cloud-platform=KUBERNETES",
+				"spring.config.import=kubernetes:, optional:configserver:", "dummy.config.loader.enabled=true" })
+class Fabric8ConfigServerTest {
+
+	private static WireMockServer wireMockServer;
+
+	@Autowired
+	private ApplicationContext applicationContext;
+
+	@BeforeAll
+	static void beforeAll() {
+		wireMockServer = new WireMockServer(options().port(8888));
+		wireMockServer.start();
+		WireMock.configureFor("localhost", wireMockServer.port());
+	}
+
+	@AfterAll
+	static void after() {
+		WireMock.shutdownServer();
+		wireMockServer.stop();
+	}
+
+	@Test
+	void test() {
+		stubFor(get(urlEqualTo("/application/default")).willReturn(aResponse().withStatus(200).withBody("{}")));
+		Assertions.assertThat(applicationContext).isNotNull();
+	}
+
+	@SpringBootApplication
+	protected static class TestConfig {
+
+	}
+
+}

spring-cloud-kubernetes-fabric8-discovery/src/test/resources/META-INF/spring.factories

@@ -0,0 +1,2 @@
+org.springframework.boot.context.config.ConfigDataLocationResolver=\
+org.springframework.cloud.kubernetes.DummyConfigDataLocationResolver