[BEAM-9364] Refactor KafkaIO to use DeserializerProviders

sdks/java/io/kafka/build.gradle

@@ -52,6 +52,7 @@ dependencies {
  testCompile project(path: ":sdks:java:testing:test-utils", configuration: "testRuntime")
  // For testing Cross-language transforms
  testCompile project(":runners:core-construction-java")
+ testCompile library.java.avro
  testCompile library.java.hamcrest_core
  testCompile library.java.hamcrest_library
  testCompile library.java.junit

sdks/java/io/kafka/src/main/java/org/apache/beam/sdk/io/kafka/ConfluentSchemaRegistryDeserializerProvider.java

@@ -0,0 +1,106 @@
+/*
+ * 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
+ *
+ * https://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.beam.sdk.io.kafka;
+
+import static org.apache.beam.vendor.guava.v26_0_jre.com.google.common.base.Preconditions.checkArgument;
+
+import io.confluent.kafka.schemaregistry.client.CachedSchemaRegistryClient;
+import io.confluent.kafka.schemaregistry.client.SchemaMetadata;
+import io.confluent.kafka.schemaregistry.client.SchemaRegistryClient;
+import io.confluent.kafka.schemaregistry.client.rest.exceptions.RestClientException;
+import io.confluent.kafka.serializers.AbstractKafkaAvroSerDeConfig;
+import io.confluent.kafka.serializers.KafkaAvroDeserializer;
+import java.io.IOException;
+import java.util.Map;
+import org.apache.avro.Schema;
+import org.apache.beam.sdk.annotations.Experimental;
+import org.apache.beam.sdk.annotations.Experimental.Kind;
+import org.apache.beam.sdk.coders.AvroCoder;
+import org.apache.beam.sdk.coders.Coder;
+import org.apache.beam.sdk.coders.CoderRegistry;
+import org.apache.beam.sdk.transforms.SerializableFunction;
+import org.apache.beam.vendor.guava.v26_0_jre.com.google.common.annotations.VisibleForTesting;
+import org.apache.beam.vendor.guava.v26_0_jre.com.google.common.collect.ImmutableMap;
+import org.apache.kafka.common.serialization.Deserializer;
+
+/**
+ * A {@link DeserializerProvider} that uses <a
+ * href="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/confluentinc/schema-registry">Confluent Schema Registry</a> to resolve a
+ * {@link Deserializer}s and {@link Coder} given a subject.
+ */
+@Experimental(Kind.SOURCE_SINK)
+public class ConfluentSchemaRegistryDeserializerProvider<T> implements DeserializerProvider<T> {
+ private final SerializableFunction<Void, SchemaRegistryClient> schemaRegistryClientProviderFn;
+ private final String schemaRegistryUrl;
+ private final String subject;
+
+ @VisibleForTesting
+ ConfluentSchemaRegistryDeserializerProvider(
+ SerializableFunction<Void, SchemaRegistryClient> schemaRegistryClientProviderFn,
+ String schemaRegistryUrl,
+ String subject) {
+ checkArgument(
+ schemaRegistryClientProviderFn != null,
+ "You should provide a schemaRegistryClientProviderFn.");
+ checkArgument(schemaRegistryUrl != null, "You should provide a schemaRegistryUrl.");
+ checkArgument(subject != null, "You should provide a subject to fetch the schema from.");
+ this.schemaRegistryClientProviderFn = schemaRegistryClientProviderFn;
+ this.schemaRegistryUrl = schemaRegistryUrl;
+ this.subject = subject;
+ }
+
+ public static <T> ConfluentSchemaRegistryDeserializerProvider<T> of(
+ String schemaRegistryUrl, String subject) {
+ return new ConfluentSchemaRegistryDeserializerProvider(
+ (SerializableFunction<Void, SchemaRegistryClient>)
+ input -> new CachedSchemaRegistryClient(schemaRegistryUrl, Integer.MAX_VALUE),
+ schemaRegistryUrl,
+ subject);
+ }
+
+ @Override
+ public Deserializer<T> getDeserializer(Map<String, ?> configs, boolean isKey) {
+ ImmutableMap<String, Object> csrConfig =
+ ImmutableMap.<String, Object>builder()
+ .putAll(configs)
+ .put(AbstractKafkaAvroSerDeConfig.SCHEMA_REGISTRY_URL_CONFIG, schemaRegistryUrl)
+ .build();
+ Deserializer<T> deserializer =
+ (Deserializer<T>) new KafkaAvroDeserializer(getSchemaRegistryClient());
+ deserializer.configure(csrConfig, isKey);
+ return deserializer;
+ }
+
+ @Override
+ public Coder<T> getCoder(CoderRegistry coderRegistry) {
+ final Schema avroSchema = new Schema.Parser().parse(getSchemaMetadata().getSchema());
+ return (Coder<T>) AvroCoder.of(avroSchema);
+ }
+
+ private SchemaMetadata getSchemaMetadata() {
+ try {
+ return getSchemaRegistryClient().getLatestSchemaMetadata(subject);
+ } catch (IOException | RestClientException e) {
+ throw new RuntimeException("Unable to get latest schema metadata for subject: " + subject, e);
+ }
+ }
+
+ private SchemaRegistryClient getSchemaRegistryClient() {
+ return this.schemaRegistryClientProviderFn.apply(null);
+ }
+}

sdks/java/io/kafka/src/main/java/org/apache/beam/sdk/io/kafka/CSRClientProvider.java → sdks/java/io/kafka/src/main/java/org/apache/beam/sdk/io/kafka/DeserializerProvider.java

@@ -17,23 +17,19 @@
  */
 package org.apache.beam.sdk.io.kafka;
 
-import io.confluent.kafka.schemaregistry.client.SchemaRegistryClient;
 import java.io.Serializable;
+import java.util.Map;
+import org.apache.beam.sdk.annotations.Experimental;
+import org.apache.beam.sdk.annotations.Experimental.Kind;
+import org.apache.beam.sdk.coders.Coder;
+import org.apache.beam.sdk.coders.CoderRegistry;
+import org.apache.kafka.common.serialization.Deserializer;
 
-/**
- * Provides instances of Confluent Schema Registry client, schema registry url, key and value
- * subjects.
- *
- * <p>Please note, that any instance of {@link CSRClientProvider} must be {@link Serializable} to
- * ensure it can be sent to worker machines.
- */
-public interface CSRClientProvider extends Serializable {
-
- SchemaRegistryClient getCSRClient();
-
- String getSchemaRegistryUrl();
+/** Provides a configured {@link Deserializer} instance and its associated {@link Coder}. */
+@Experimental(Kind.SOURCE_SINK)
+interface DeserializerProvider<T> extends Serializable {
 
- String getKeySchemaSubject();
+ Deserializer<T> getDeserializer(Map<String, ?> configs, boolean isKey);
 
- String getValueSchemaSubject();
+ Coder<T> getCoder(CoderRegistry coderRegistry);
 }