Copilot commented on code in PR #23934:
URL: https://github.com/apache/kafka/pull/23934#discussion_r4358864199
##########
clients/src/main/java/org/apache/kafka/clients/ClientUtils.java:
##########
@@ -85,19 +87,26 @@ private static List<InetSocketAddress> resolveAddress(
}
}
} else {
- InetSocketAddress address = new InetSocketAddress(host, port);
- if (address.isUnresolved()) {
+ // Preserve the pre-existing single-address-per-host contract of
this lookup mode
+ // (equivalent to InetSocketAddress(host, port)'s implicit
resolution): take only the
+ // first address the resolver returns, rather than all of them
like the branch above.
+ try {
+ InetAddress[] resolved = hostResolver.resolve(host);
+ addresses.add(new InetSocketAddress(resolved[0], port));
Review Comment:
When the injected resolver returns an unnamed InetAddress, such as one
created from an IP literal, this constructor drops the configured bootstrap
hostname. Cluster.bootstrap() copies the socket's getHostString() into
Node.host(), and ClusterConnectionStates later resolves that value again. A
resolver keyed by the bootstrap hostname therefore receives the numeric IP on
connection attempts and can fail even though bootstrap resolution succeeded.
Preserve the configured hostname alongside the resolved address without another
DNS lookup, retaining any IPv6 scope, and add a regression test with an unnamed
resolver result.
##########
clients/clients-integration-tests/src/test/java/org/apache/kafka/clients/admin/AsyncBootstrapResolutionTest.java:
##########
@@ -0,0 +1,84 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one or more
+ * contributor license agreements. See the NOTICE file distributed with
+ * this work for additional information regarding copyright ownership.
+ * The ASF licenses this file to You 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 org.apache.kafka.clients.admin;
+
+import org.apache.kafka.clients.CommonClientConfigs;
+import org.apache.kafka.clients.DefaultHostResolver;
+import org.apache.kafka.clients.HostResolver;
+import org.apache.kafka.common.test.ClusterInstance;
+import org.apache.kafka.common.test.api.ClusterTest;
+import org.apache.kafka.common.test.api.ClusterTestDefaults;
+import org.apache.kafka.common.test.api.Type;
+import org.apache.kafka.common.utils.Utils;
+
+import java.net.InetAddress;
+import java.net.UnknownHostException;
+import java.util.Map;
+import java.util.concurrent.TimeUnit;
+import java.util.concurrent.atomic.AtomicInteger;
+
+import static org.junit.jupiter.api.Assertions.assertDoesNotThrow;
+import static org.junit.jupiter.api.Assertions.assertTrue;
+
+/**
+ * Prototype/spike: proves that KafkaAdminClient#createInternal's HostResolver
injection point
+ * (the same one ConcurrentListOffsetsRequestTest uses) now also controls
KIP-909 async bootstrap
+ * DNS resolution, after routing NetworkClient's bootstrap resolution through
the injected
+ * HostResolver instead of calling InetAddress/InetSocketAddress directly.
+ */
+@ClusterTestDefaults(
+ types = {Type.KRAFT},
+ brokers = 1
+)
+public class AsyncBootstrapResolutionTest {
+ private final ClusterInstance clusterInstance;
+
+ AsyncBootstrapResolutionTest(ClusterInstance clusterInstance) {
+ this.clusterInstance = clusterInstance;
+ }
+
+ @ClusterTest
+ public void adminClientRecoversAfterTransientBootstrapDnsFailure() throws
Exception {
+ clusterInstance.waitForReadyBrokers();
+
+ String bootstrapServers = clusterInstance.bootstrapServers();
+ String host = Utils.getHost(bootstrapServers);
+ InetAddress realAddress = new DefaultHostResolver().resolve(host)[0];
+
+ AtomicInteger attempts = new AtomicInteger();
+ HostResolver flakyThenWorking = resolveHost -> {
+ if (attempts.getAndIncrement() < 2) {
+ throw new UnknownHostException("Simulated transient DNS
failure for " + resolveHost);
+ }
+ return new InetAddress[] {realAddress};
+ };
+
+ Map<String, Object> props = Map.of(
+ CommonClientConfigs.BOOTSTRAP_SERVERS_CONFIG, bootstrapServers,
Review Comment:
This test can pass even if bootstrap resolution bypasses the injected
resolver. The real cluster hostname resolves through JVM DNS, and the existing
connection-time resolver can consume the two simulated failures before
listTopics succeeds, satisfying both assertions. Use a bootstrap hostname that
only the injected resolver can resolve, while retaining the real broker port,
so reverting bootstrap injection makes this test fail.
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