get k8s pods siblings ip addresses via headless service (#2847)

Signed-off-by: yosrixp <[email protected]>
Co-authored-by: yosrixp <[email protected]>

libs/java/server_k8s_common/src/main/java/io/athenz/server/k8s/common/impl/KubernetesPodResolverUtil.java

@@ -0,0 +1,28 @@
+/*
+ * Copyright The Athenz 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
+ *
+ *     http://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 io.athenz.server.k8s.common.impl;
+
+import java.net.InetAddress;
+import java.net.UnknownHostException;
+
+public class KubernetesPodResolverUtil {
+    public static InetAddress[] getSiblingPodIPs(String headlessServiceName) throws UnknownHostException {
+        if (headlessServiceName == null || headlessServiceName.isBlank()) {
+            throw new IllegalArgumentException("k8s headless FQDN name is required");
+        }
+        return InetAddress.getAllByName(headlessServiceName);
+    }
+}

libs/java/server_k8s_common/src/test/java/io/athenz/server/k8s/common/impl/KubernetesPodResolverUtilTest.java

@@ -0,0 +1,83 @@
+/*
+ * Copyright The Athenz 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
+ *
+ *     http://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 io.athenz.server.k8s.common.impl;
+
+import org.mockito.MockedStatic;
+import org.mockito.Mockito;
+import org.testng.Assert;
+import org.testng.annotations.Test;
+
+import java.net.InetAddress;
+import java.net.UnknownHostException;
+
+public class KubernetesPodResolverUtilTest {
+
+    @Test
+    public void testGetPodSiblings() throws UnknownHostException {
+        String serviceName = "msd.api.svc.cluster.local";
+        InetAddress podAddress1 = Mockito.mock(InetAddress.class);
+        InetAddress podAddress2 = Mockito.mock(InetAddress.class);
+        Mockito.when(podAddress1.getHostAddress()).thenReturn("192.168.1.10");
+        Mockito.when(podAddress2.getHostAddress()).thenReturn("192.168.1.11");
+
+        MockedStatic<InetAddress> inetAddressMock = Mockito.mockStatic(InetAddress.class);
+        inetAddressMock.when(() -> InetAddress.getAllByName(serviceName)).thenReturn(new InetAddress[]{podAddress1, podAddress2});
+        InetAddress[] podsIPs = KubernetesPodResolverUtil.getSiblingPodIPs(serviceName);
+        Assert.assertEquals(podsIPs.length, 2);
+        inetAddressMock.close();
+    }
+
+    @Test
+    public void testGetPodSiblingsEmptyServiceNameException() {
+        String serviceName = "";
+        Exception ex = null;
+        try {
+            KubernetesPodResolverUtil.getSiblingPodIPs(serviceName);
+        } catch (IllegalArgumentException | UnknownHostException e) {
+            ex = e;
+        }
+        if (ex == null) {
+            Assert.fail("expected IllegalArgumentException not thrown");
+        }
+
+        Exception nullEx = null;
+        try {
+            KubernetesPodResolverUtil.getSiblingPodIPs(null);
+        } catch (IllegalArgumentException | UnknownHostException e) {
+            nullEx = e;
+        }
+        if (nullEx == null) {
+            Assert.fail("expected IllegalArgumentException not thrown");
+        }
+    }
+
+    @Test
+    public void testGetPodSiblingsInvalidHostnameException() {
+        String serviceName = "foo";
+        MockedStatic<InetAddress> inetAddressMock = Mockito.mockStatic(InetAddress.class);
+        inetAddressMock.when(() -> InetAddress.getAllByName(serviceName)).thenThrow(UnknownHostException.class);
+        Exception ex = null;
+        try {
+            KubernetesPodResolverUtil.getSiblingPodIPs(serviceName);
+        } catch (IllegalArgumentException | UnknownHostException e) {
+            ex = e;
+        }
+        if (ex == null) {
+            Assert.fail("expected UnknownHostException not thrown");
+        }
+        inetAddressMock.close();
+    }
+}