Lazily create the KubernetesProfileApplicationListener

This is needed in order to avoid causing problems to environments
that have spring-cloud-kubernetes on the classpath but don't want to
enable it

Fixes: #131

spring-cloud-kubernetes-core/src/main/java/org/springframework/cloud/kubernetes/profile/KubernetesApplicationContextInitializer.java

@@ -17,7 +17,8 @@
 package org.springframework.cloud.kubernetes.profile;
 
 import io.fabric8.kubernetes.client.DefaultKubernetesClient;
-import org.springframework.cloud.kubernetes.PodUtils;
+import java.util.function.Supplier;
+import org.springframework.cloud.kubernetes.LazilyInstantiate;
 import org.springframework.cloud.kubernetes.StandardPodUtils;
 import org.springframework.context.ApplicationContextInitializer;
 import org.springframework.context.ConfigurableApplicationContext;
@@ -26,30 +27,38 @@ import org.springframework.core.Ordered;
 public class KubernetesApplicationContextInitializer implements
         ApplicationContextInitializer<ConfigurableApplicationContext>, Ordered {
 
-    private final KubernetesProfileApplicationListener listener;
     private static final int ORDER = 100;
 
-    public KubernetesApplicationContextInitializer() {
-        //If we are inside Kubernetes this should be perfectly valid.
-        //If not then we won't add the Kubernetes profile anyway.
-        this(new StandardPodUtils(new DefaultKubernetesClient()));
-    }
+    private final Supplier<KubernetesProfileApplicationListener> listenerSupplier;
 
-    public KubernetesApplicationContextInitializer(PodUtils utils) {
-        this(new KubernetesProfileApplicationListener(utils));
-    }
+	public KubernetesApplicationContextInitializer() {
+		this(LazilyInstantiate.using(() ->
+			//If we are inside Kubernetes this should be perfectly valid.
+			//If not then we won't add the Kubernetes profile anyway.
+			new KubernetesProfileApplicationListener(
+				new StandardPodUtils(new DefaultKubernetesClient()))
+		));
+	}
 
-    public KubernetesApplicationContextInitializer(KubernetesProfileApplicationListener listener) {
-        this.listener = listener;
-    }
+	public KubernetesApplicationContextInitializer(
+		Supplier<KubernetesProfileApplicationListener> listenerSupplier) {
+		this.listenerSupplier = listenerSupplier;
+	}
 
-    @Override
+	@Override
     public int getOrder() {
         return ORDER;
     }
 
     @Override
     public void initialize(ConfigurableApplicationContext applicationContext) {
-        listener.addKubernetesProfile(applicationContext.getEnvironment());
+    	if(isKubernetesEnabled(applicationContext)){
+			listenerSupplier.get().addKubernetesProfile(applicationContext.getEnvironment());
+		}
     }
+
+	private Boolean isKubernetesEnabled(ConfigurableApplicationContext applicationContext) {
+		return applicationContext.getEnvironment()
+			.getProperty("spring.cloud.kubernetes.enabled", Boolean.class, true);
+	}
 }

spring-cloud-kubernetes-core/src/test/java/org/springframework/cloud/kubernetes/profile/KubernetesApplicationContextInitializerTest.java

@@ -0,0 +1,60 @@
+package org.springframework.cloud.kubernetes.profile;
+
+import static org.mockito.Mockito.never;
+import static org.mockito.Mockito.verify;
+import static org.mockito.Mockito.when;
+
+import java.util.function.Supplier;
+import org.junit.Before;
+import org.junit.Test;
+import org.junit.runner.RunWith;
+import org.mockito.Mock;
+import org.mockito.junit.MockitoJUnitRunner;
+import org.springframework.context.ConfigurableApplicationContext;
+import org.springframework.core.env.ConfigurableEnvironment;
+
+@RunWith(MockitoJUnitRunner.class)
+public class KubernetesApplicationContextInitializerTest {
+
+	@Mock
+	private Supplier<KubernetesProfileApplicationListener> listenerSupplier;
+
+	@Mock
+	private ConfigurableApplicationContext applicationContext;
+
+	@Mock
+	private ConfigurableEnvironment environment;
+
+	@Mock
+	private KubernetesProfileApplicationListener listener;
+
+	private KubernetesApplicationContextInitializer initializer;
+
+	@Before
+	public void setUp() {
+		initializer = new KubernetesApplicationContextInitializer(listenerSupplier);
+		when(applicationContext.getEnvironment()).thenReturn(environment);
+		when(listenerSupplier.get()).thenReturn(listener);
+	}
+
+	@Test
+	public void kubernetesDisabled() {
+		when(environment.getProperty("spring.cloud.kubernetes.enabled", Boolean.class, true))
+			.thenReturn(false);
+
+		initializer.initialize(applicationContext);
+
+		verify(listenerSupplier, never()).get();
+	}
+
+	@Test
+	public void kubernetesEnabled() {
+		when(environment.getProperty("spring.cloud.kubernetes.enabled", Boolean.class, true))
+			.thenReturn(true);
+
+		initializer.initialize(applicationContext);
+
+		verify(listenerSupplier).get();
+		verify(listener).addKubernetesProfile(environment);
+	}
+}