Github user pvillard31 commented on a diff in the pull request:
https://github.com/apache/nifi/pull/366#discussion_r60828535
--- Diff:
nifi-nar-bundles/nifi-kafka-bundle/nifi-kafka-pubsub-processors/src/main/java/org/apache/nifi/processors/kafka/pubsub/ConsumeKafka.java
---
@@ -0,0 +1,213 @@
+/*
+ * 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.nifi.processors.kafka.pubsub;
+
+import java.io.IOException;
+import java.io.OutputStream;
+import java.nio.charset.StandardCharsets;
+import java.util.ArrayList;
+import java.util.Collections;
+import java.util.List;
+import java.util.Map;
+import java.util.Properties;
+import java.util.Set;
+import java.util.concurrent.TimeUnit;
+import java.util.concurrent.atomic.AtomicInteger;
+
+import org.apache.kafka.clients.consumer.ConsumerConfig;
+import org.apache.kafka.clients.consumer.ConsumerRecord;
+import org.apache.kafka.clients.consumer.ConsumerRecords;
+import org.apache.kafka.clients.consumer.KafkaConsumer;
+import org.apache.kafka.common.serialization.ByteArrayDeserializer;
+import org.apache.nifi.annotation.behavior.InputRequirement;
+import org.apache.nifi.annotation.behavior.InputRequirement.Requirement;
+import org.apache.nifi.annotation.documentation.CapabilityDescription;
+import org.apache.nifi.annotation.documentation.Tags;
+import org.apache.nifi.annotation.lifecycle.OnStopped;
+import org.apache.nifi.components.AllowableValue;
+import org.apache.nifi.components.PropertyDescriptor;
+import org.apache.nifi.flowfile.FlowFile;
+import org.apache.nifi.processor.ProcessContext;
+import org.apache.nifi.processor.ProcessSession;
+import org.apache.nifi.processor.Relationship;
+import org.apache.nifi.processor.exception.ProcessException;
+import org.apache.nifi.processor.io.OutputStreamCallback;
+import org.apache.nifi.processor.util.StandardValidators;
+
+@InputRequirement(Requirement.INPUT_FORBIDDEN)
+@CapabilityDescription("Consumes messages from Apache Kafka")
+@Tags({ "Kafka", "Get", "Ingest", "Ingress", "Topic", "PubSub", "Consume"
})
+public class ConsumeKafka extends
AbstractKafkaProcessor<KafkaConsumer<byte[], byte[]>> {
+
+ static final AllowableValue OFFSET_EARLIEST = new
AllowableValue("earliest", "earliest", "Automatically reset the offset to the
earliest offset");
+
+ static final AllowableValue OFFSET_LATEST = new
AllowableValue("latest", "latest", "Automatically reset the offset to the
latest offset");
+
+ static final AllowableValue OFFSET_NONE = new AllowableValue("none",
"none", "Throw exception to the consumer if no previous offset is found for the
consumer's group");
+
+ static final PropertyDescriptor GROUP_ID = new
PropertyDescriptor.Builder()
+ .name(ConsumerConfig.GROUP_ID_CONFIG)
+ .displayName("Group ID")
+ .description("A Group ID is used to identify consumers that
are within the same consumer group. Corresponds to Kafka's 'group.id'
property.")
+ .required(true)
+ .addValidator(StandardValidators.NON_BLANK_VALIDATOR)
+ .expressionLanguageSupported(false)
+ .build();
+ static final PropertyDescriptor AUTO_OFFSET_RESET = new
PropertyDescriptor.Builder()
+ .name(ConsumerConfig.AUTO_OFFSET_RESET_CONFIG)
+ .displayName("Offset Reset")
+ .description("Allows you to manage teh condition when there is
no initial offset in Kafka or if the current offset does not exist any "
+ + "more on the server (e.g. because that data has been
deleted). Corresponds to Kafka's 'auto.offset.reset' property.")
+ .required(true)
+ .allowableValues(OFFSET_EARLIEST, OFFSET_LATEST, OFFSET_NONE)
+ .defaultValue(OFFSET_LATEST.getValue())
+ .build();
+ static final PropertyDescriptor MESSAGE_DEMARCATOR =
MESSAGE_DEMARCATOR_BUILDER
+ .description("Since KafkaConsumer receives messages in
batches, this property allows you to provide a string (interpreted as UTF-8) to
use "
+ + "for demarcating apart multiple Kafka messages when
building a single FlowFile. If not specified, all messages received form Kafka "
+ + "will be merged into a single content within
a FlowFile. By default it will use 'new line' charcater to demarcate individual
messages."
+ + "To enter special character such as 'new
line' use Shift+Enter.")
+ .defaultValue("\n")
+ .build();
+
+
+ static final List<PropertyDescriptor> descriptors;
+
+ static final Set<Relationship> relationships;
+
+ private volatile byte[] demarcatorBytes;
+
+ private volatile String topic;
+
+ /*
+ * Will ensure that list of PropertyDescriptors is build only once,
since
+ * all other lifecycle methods are invoked multiple times.
+ */
+ static {
+ List<PropertyDescriptor> _descriptors = new ArrayList<>();
+ _descriptors.addAll(sharedDescriptors);
+ _descriptors.add(GROUP_ID);
+ _descriptors.add(AUTO_OFFSET_RESET);
+ _descriptors.add(MESSAGE_DEMARCATOR);
+ descriptors = Collections.unmodifiableList(_descriptors);
+
+ relationships = Collections.unmodifiableSet(sharedRelationships);
+ }
+
+ /**
+ *
+ */
+ @Override
+ public Set<Relationship> getRelationships() {
+ return relationships;
+ }
+
+ /**
+ * Will unsubscribe form {@link KafkaConsumer} delegating to 'super'
to do
+ * the rest.
+ */
+ @Override
+ @OnStopped
+ public void close() {
+ if (this.kafkaResource != null) {
+ try {
+ this.kafkaResource.unsubscribe();
+ } finally { // in the event the above fails
+ super.close();
+ }
+ }
+ }
+
+ /**
+ *
+ */
+ @Override
+ protected List<PropertyDescriptor> getSupportedPropertyDescriptors() {
+ return descriptors;
+ }
+
+ /**
+ * Will rendezvous with Kafka by performing the following:
+ * <br>
+ * - poll {@link ConsumerRecords} from {@link KafkaConsumer} in a
+ * non-blocking manner, signaling yield if no records were received
from
+ * Kafka
+ * <br>
+ * - if records were received form Kafka, the are written to a newly
created
+ * {@link FlowFile}'s {@link OutputStream} using a provided demarcator
(see
+ * {@link #MESSAGE_DEMARCATOR}
+ */
+ @Override
+ protected void rendezvousWithKafka(ProcessContext context,
ProcessSession processSession) throws ProcessException {
+ ConsumerRecords<byte[], byte[]> consumedRecords =
this.kafkaResource.poll(100);
+ if (consumedRecords != null && !consumedRecords.isEmpty()) {
+ long start = System.nanoTime();
+ FlowFile flowFile = processSession.create();
+ final AtomicInteger messageCounter = new AtomicInteger();
+
+ for (final ConsumerRecord<byte[], byte[]> consumedRecord :
consumedRecords) {
+ flowFile = processSession.append(flowFile, new
OutputStreamCallback() {
+ @Override
+ public void process(final OutputStream out) throws
IOException {
+ if (messageCounter.getAndIncrement() > 0) {
+ out.write(ConsumeKafka.this.demarcatorBytes);
+ }
+ out.write(consumedRecord.value());
+ }
+ });
+ }
+
+ this.releaseFlowFile(flowFile, processSession,
flowFile.getAttributes(), start, messageCounter.get() - 1);
+ this.kafkaResource.commitSync();
+ } else {
+ context.yield();
+ }
+ }
+
+ /**
+ * Builds and instance of {@link KafkaConsumer} and subscribes to a
provided
+ * topic.
+ */
+ @Override
+ protected KafkaConsumer<byte[], byte[]>
buildKafkaResource(ProcessContext context, ProcessSession session) throws
ProcessException {
+ this.demarcatorBytes =
context.getProperty(MESSAGE_DEMARCATOR).evaluateAttributeExpressions().getValue().getBytes(StandardCharsets.UTF_8);
+ this.topic =
context.getProperty(TOPIC).evaluateAttributeExpressions().getValue();
+
+ Properties kafkaProperties = this.buildKafkaProperties(context);
+ kafkaProperties.put(ConsumerConfig.KEY_DESERIALIZER_CLASS_CONFIG,
ByteArrayDeserializer.class.getName());
+
kafkaProperties.put(ConsumerConfig.VALUE_DESERIALIZER_CLASS_CONFIG,
ByteArrayDeserializer.class.getName());
+
+ KafkaConsumer<byte[], byte[]> consumer = new
KafkaConsumer<>(kafkaProperties);
+ consumer.subscribe(Collections.singletonList(this.topic));
+ return consumer;
+ }
+
+ /**
+ * Will release flow file. Releasing of the flow file in the context
of this
+ * operation implies the following:
+ *
+ * If Empty then remove from session and return If has something then
+ * transfer to {@link #REL_SUCCESS}
+ */
+ private void releaseFlowFile(FlowFile flowFile, ProcessSession
session, Map<String, String> attributes, long start, int msgCount) {
+ flowFile = session.putAllAttributes(flowFile, attributes);
+ long millis = TimeUnit.NANOSECONDS.toMillis(System.nanoTime() -
start);
+ session.getProvenanceReporter().receive(flowFile, "kafka://" +
this.topic, "Received " + msgCount + " Kafka messages", millis);
--- End diff --
I think IP bootstrap servers IPs is/are missing if the URI:
kafka://<IPs/Ports>/topic, no?
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