Add support to detect Kubernetes platform in CloudPlatform

Closes gh-15537

spring-boot-project/spring-boot/src/main/java/org/springframework/boot/cloud/CloudPlatform.java

@@ -16,7 +16,11 @@
 
 package org.springframework.boot.cloud;
 
+import org.springframework.core.env.ConfigurableEnvironment;
 import org.springframework.core.env.Environment;
+import org.springframework.core.env.MapPropertySource;
+import org.springframework.core.env.StandardEnvironment;
+import org.springframework.util.StringUtils;
 
 /**
  * Simple detection for well known cloud platforms. For more advanced cloud provider
@@ -63,6 +67,33 @@ public enum CloudPlatform {
 			return environment.containsProperty("HC_LANDSCAPE");
 		}
 
+	},
+
+	/**
+	 * Kubernetes platform.
+	 */
+	KUBERNETES {
+		@Override
+		public boolean isActive(Environment environment) {
+			if (environment instanceof ConfigurableEnvironment) {
+				MapPropertySource propertySource = (MapPropertySource) ((ConfigurableEnvironment) environment)
+						.getPropertySources()
+						.get(StandardEnvironment.SYSTEM_ENVIRONMENT_PROPERTY_SOURCE_NAME);
+				if (propertySource != null) {
+					for (String name : propertySource.getPropertyNames()) {
+						if (name.endsWith("_SERVICE_HOST")) {
+							String serviceName = StringUtils.split(name,
+									"_SERVICE_HOST")[0];
+							if (propertySource
+									.getProperty(serviceName + "_SERVICE_PORT") != null) {
+								return true;
+							}
+						}
+					}
+				}
+			}
+			return false;
+		}
 	};
 
 	/**

spring-boot-project/spring-boot/src/test/java/org/springframework/boot/cloud/CloudPlatformTests.java

@@ -16,9 +16,16 @@
 
 package org.springframework.boot.cloud;
 
+import java.util.Collections;
+import java.util.HashMap;
+import java.util.Map;
+
 import org.junit.Test;
 
 import org.springframework.core.env.Environment;
+import org.springframework.core.env.PropertySource;
+import org.springframework.core.env.StandardEnvironment;
+import org.springframework.core.env.SystemEnvironmentPropertySource;
 import org.springframework.mock.env.MockEnvironment;
 
 import static org.assertj.core.api.Assertions.assertThat;
@@ -79,4 +86,29 @@ public class CloudPlatformTests {
 		assertThat(platform.isActive(environment)).isTrue();
 	}
 
+	@Test
+	public void getActiveWhenHasServiceHostAndServicePortShouldReturnKubernetes() {
+		MockEnvironment environment = new MockEnvironment();
+		Map<String, Object> source = new HashMap<>();
+		source.put("EXAMPLE_SERVICE_HOST", "---");
+		source.put("EXAMPLE_SERVICE_PORT", "8080");
+		PropertySource propertySource = new SystemEnvironmentPropertySource(
+				StandardEnvironment.SYSTEM_ENVIRONMENT_PROPERTY_SOURCE_NAME, source);
+		environment.getPropertySources().addFirst(propertySource);
+		CloudPlatform platform = CloudPlatform.getActive(environment);
+		assertThat(platform).isEqualTo(CloudPlatform.KUBERNETES);
+		assertThat(platform.isActive(environment)).isTrue();
+	}
+
+	@Test
+	public void getActiveWhenHasServiceHostAndNoServicePortShouldNotReturnKubernetes() {
+		MockEnvironment environment = new MockEnvironment();
+		PropertySource propertySource = new SystemEnvironmentPropertySource(
+				StandardEnvironment.SYSTEM_ENVIRONMENT_PROPERTY_SOURCE_NAME,
+				Collections.singletonMap("EXAMPLE_SERVICE_HOST", "---"));
+		environment.getPropertySources().addFirst(propertySource);
+		CloudPlatform platform = CloudPlatform.getActive(environment);
+		assertThat(platform).isNull();
+	}
+
 }