Fix eclipse-jkube#815: ClassCastException during oc:build when OpenSh…

…ift not present

Using OpenShiftClient to store result of `clusterAccess.createDefaultClient()` seems to
cause ClassCastException when return value is of type DefaultKubernetesClient.

Instead, Use a temporaty KubernetesClient variable for `clusterAccess.createDefaultClient()`
and type cast it to OpenShiftClient in case it's adaptable to OpenShiftClient interface.

Signed-off-by: Rohan Kumar <rohaan@redhat.com>

CHANGELOG.md

@@ -21,6 +21,7 @@ Usage:
 ./scripts/extract-changelog-for-version.sh 1.3.37 5
 ```
 ### 1.5.0-SNAPSHOT
+* Fix #815: `java.lang.ClassCastException` during `oc:build` when OpenShift not present
 
 ### 1.4.0 (2021-07-27)
 * Fix #253: Refactor JKubeServiceHub's BuildService election mechanism via ServiceLoader

jkube-kit/config/service/src/main/java/org/eclipse/jkube/kit/config/service/openshift/OpenshiftBuildService.java

@@ -26,6 +26,7 @@
 import java.util.concurrent.TimeUnit;
 import java.util.concurrent.atomic.AtomicReference;
 
+import io.fabric8.kubernetes.client.KubernetesClient;
 import org.eclipse.jkube.kit.build.api.auth.AuthConfig;
 import org.eclipse.jkube.kit.build.service.docker.auth.AuthConfigFactory;
 import org.eclipse.jkube.kit.common.KitLogger;
@@ -231,10 +232,11 @@ private void initClient() {
             clusterAccess = new ClusterAccess(log,
                 ClusterConfiguration.from(System.getProperties(), jKubeServiceHub.getConfiguration().getProject().getProperties()).build());
         }
-        client = clusterAccess.createDefaultClient();
-        if (!isOpenShift(client)) {
+        KubernetesClient k8sClient = clusterAccess.createDefaultClient();
+        if (!isOpenShift(k8sClient)) {
             throw new IllegalStateException("OpenShift platform has been specified but OpenShift has not been detected!");
         }
+        client = (OpenShiftClient) k8sClient;
     }
 
     private void validateSourceType(String buildName, BuildConfigSpec spec) {

jkube-kit/config/service/src/test/java/org/eclipse/jkube/kit/config/service/openshift/OpenShiftBuildServiceTest.java

@@ -16,12 +16,17 @@
 import mockit.Mocked;
 import mockit.Verifications;
 import org.eclipse.jkube.kit.common.RegistryConfig;
+import org.eclipse.jkube.kit.config.image.ImageConfiguration;
+import org.eclipse.jkube.kit.config.image.build.BuildConfiguration;
 import org.eclipse.jkube.kit.config.service.JKubeServiceException;
 import org.eclipse.jkube.kit.config.service.JKubeServiceHub;
 import org.junit.Test;
 
 import java.util.Collections;
 
+import static org.assertj.core.api.Assertions.assertThat;
+import static org.junit.Assert.assertThrows;
+
 @SuppressWarnings("unused")
 public class OpenShiftBuildServiceTest {
 
@@ -39,4 +44,23 @@ public void push_withDefaults_shouldLogWarning() throws JKubeServiceException {
     }};
     // @formatter:on
   }
+
+  @Test
+  public void initClient_withNoOpenShift_shouldThrowException() {
+    // Given
+    //  @formatter:off
+    ImageConfiguration imageConfiguration = ImageConfiguration.builder()
+      .name("foo/bar:latest")
+      .build(BuildConfiguration.builder()
+        .from("baseimage:latest")
+        .build())
+      .build();
+    // @formatter:on
+    OpenshiftBuildService openshiftBuildService = new OpenshiftBuildService(jKubeServiceHub);
+
+    // When + Then
+    IllegalStateException illegalStateException = assertThrows(IllegalStateException.class, () -> openshiftBuildService.build(imageConfiguration));
+    assertThat(illegalStateException.getMessage())
+        .isEqualTo("OpenShift platform has been specified but OpenShift has not been detected!");
+  }
 }