Add externalname support (#1243)

spring-cloud-kubernetes-commons/src/main/java/org/springframework/cloud/kubernetes/commons/discovery/DefaultKubernetesServiceInstance.java

@@ -102,6 +102,10 @@ public record DefaultKubernetesServiceInstance(String instanceId, String service
 	}
 
 	private URI createUri(String scheme, String host, int port) {
+		// assume ExternalName type of service
+		if (port == -1) {
+			return URI.create(host);
+		}
 		return URI.create(scheme + "://" + host + ":" + port);
 	}
 }

spring-cloud-kubernetes-commons/src/main/java/org/springframework/cloud/kubernetes/commons/discovery/KubernetesDiscoveryConstants.java

@@ -67,4 +67,14 @@ public final class KubernetesDiscoveryConstants {
 	 */
 	public static final String ENDPOINT_SLICE = "EndpointSlice";
 
+	/**
+	 * ExternalName type of service.
+	 */
+	public static final String EXTERNAL_NAME = "ExternalName";
+
+	/**
+	 * Type of the service.
+	 */
+	public static final String SERVICE_TYPE = "type";
+
 }

spring-cloud-kubernetes-commons/src/main/java/org/springframework/cloud/kubernetes/commons/discovery/KubernetesDiscoveryProperties.java

@@ -20,6 +20,7 @@ import java.util.Map;
 import java.util.Set;
 
 import org.springframework.boot.context.properties.ConfigurationProperties;
+import org.springframework.boot.context.properties.bind.ConstructorBinding;
 import org.springframework.boot.context.properties.bind.DefaultValue;
 
 import static org.springframework.cloud.client.discovery.DiscoveryClient.DEFAULT_ORDER;
@@ -43,6 +44,8 @@ import static org.springframework.cloud.client.discovery.DiscoveryClient.DEFAULT
  * @param primaryPortName If set then the port with a given name is used as primary when
  * multiple ports are defined for a service.
  * @param useEndpointSlices use EndpointSlice instead of Endpoints
+ * @param includeExternalNameServices should the discovery also search for services that
+ * have "type: ExternalName" in their spec.
  */
 // @formatter:off
 @ConfigurationProperties("spring.cloud.kubernetes.discovery")
@@ -56,14 +59,31 @@ public record KubernetesDiscoveryProperties(
 		@DefaultValue Map<String, String> serviceLabels, String primaryPortName,
 		@DefaultValue Metadata metadata,
 		@DefaultValue("" + DEFAULT_ORDER) int order,
-		boolean useEndpointSlices) {
+		boolean useEndpointSlices,
+		boolean includeExternalNameServices) {
 // @formatter:on
 
+	@ConstructorBinding
+	public KubernetesDiscoveryProperties {
+
+	}
+
+	public KubernetesDiscoveryProperties(@DefaultValue("true") boolean enabled, boolean allNamespaces,
+			@DefaultValue Set<String> namespaces, @DefaultValue("true") boolean waitCacheReady,
+			@DefaultValue("60") long cacheLoadingTimeoutSeconds, boolean includeNotReadyAddresses, String filter,
+			@DefaultValue({ "443", "8443" }) Set<Integer> knownSecurePorts,
+			@DefaultValue Map<String, String> serviceLabels, String primaryPortName, @DefaultValue Metadata metadata,
+			@DefaultValue("" + DEFAULT_ORDER) int order, boolean useEndpointSlices) {
+		this(enabled, allNamespaces, namespaces, waitCacheReady, cacheLoadingTimeoutSeconds, includeNotReadyAddresses,
+				filter, knownSecurePorts, serviceLabels, primaryPortName, metadata, order, useEndpointSlices, false);
+	}
+
 	/**
 	 * Default instance.
 	 */
 	public static final KubernetesDiscoveryProperties DEFAULT = new KubernetesDiscoveryProperties(true, false, Set.of(),
-			true, 60, false, null, Set.of(), Map.of(), null, KubernetesDiscoveryProperties.Metadata.DEFAULT, 0, false);
+			true, 60, false, null, Set.of(), Map.of(), null, KubernetesDiscoveryProperties.Metadata.DEFAULT, 0, false,
+			false);
 
 	/**
 	 * @param addLabels include labels as metadata

spring-cloud-kubernetes-commons/src/test/java/org/springframework/cloud/kubernetes/commons/discovery/KubernetesDiscoveryPropertiesTests.java

@@ -53,6 +53,7 @@ class KubernetesDiscoveryPropertiesTests {
 					assertThat(props.primaryPortName()).isNull();
 					assertThat(props.order()).isZero();
 					assertThat(props.useEndpointSlices()).isFalse();
+					assertThat(props.includeExternalNameServices()).isFalse();
 				});
 	}
 
@@ -64,7 +65,8 @@ class KubernetesDiscoveryPropertiesTests {
 						"spring.cloud.kubernetes.discovery.metadata.labelsPrefix=labelsPrefix",
 						"spring.cloud.kubernetes.discovery.use-endpoint-slices=true",
 						"spring.cloud.kubernetes.discovery.namespaces[0]=ns1",
-						"spring.cloud.kubernetes.discovery.namespaces[1]=ns2")
+						"spring.cloud.kubernetes.discovery.namespaces[1]=ns2",
+						"spring.cloud.kubernetes.discovery.include-external-name-services=true")
 				.run(context -> {
 					KubernetesDiscoveryProperties props = context.getBean(KubernetesDiscoveryProperties.class);
 					assertThat(props).isNotNull();
@@ -84,6 +86,7 @@ class KubernetesDiscoveryPropertiesTests {
 					assertThat(props.primaryPortName()).isNull();
 					assertThat(props.order()).isZero();
 					assertThat(props.useEndpointSlices()).isTrue();
+					assertThat(props.includeExternalNameServices()).isTrue();
 				});
 	}