Github user mattyb149 commented on a diff in the pull request:
https://github.com/apache/nifi/pull/180#discussion_r51129036
--- Diff:
nifi-nar-bundles/nifi-elasticsearch-bundle/nifi-elasticsearch-processors/src/main/java/org/apache/nifi/processors/elasticsearch/FetchElasticsearch.java
---
@@ -0,0 +1,193 @@
+/*
+ * 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.elasticsearch;
+
+import org.apache.nifi.annotation.behavior.EventDriven;
+import org.apache.nifi.annotation.behavior.WritesAttribute;
+import org.apache.nifi.annotation.behavior.WritesAttributes;
+import org.apache.nifi.annotation.documentation.CapabilityDescription;
+import org.apache.nifi.annotation.documentation.Tags;
+import org.apache.nifi.components.PropertyDescriptor;
+import org.apache.nifi.expression.AttributeExpression;
+import org.apache.nifi.flowfile.FlowFile;
+import org.apache.nifi.logging.ProcessorLog;
+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;
+import org.elasticsearch.ElasticsearchParseException;
+import org.elasticsearch.ElasticsearchTimeoutException;
+import org.elasticsearch.action.get.GetResponse;
+import org.elasticsearch.client.transport.NoNodeAvailableException;
+import org.elasticsearch.node.NodeClosedException;
+import org.elasticsearch.transport.ReceiveTimeoutTransportException;
+
+import java.io.IOException;
+import java.io.OutputStream;
+import java.nio.charset.StandardCharsets;
+import java.util.ArrayList;
+import java.util.Collections;
+import java.util.HashSet;
+import java.util.List;
+import java.util.Set;
+
+
+@EventDriven
+@Tags({"elasticsearch", "fetch", "read"})
+@CapabilityDescription("Retrieves a document from Elasticsearch using the
specified connection properties and the identifier of the document to retrieve")
+@WritesAttributes({
+ @WritesAttribute(attribute = "filename", description = "The
document identifier"),
+ @WritesAttribute(attribute = "es.index", description = "The
Elasticsearch index containing the document"),
+ @WritesAttribute(attribute = "es.type", description = "The
Elasticsearch document type")
+})
+public class FetchElasticsearch extends AbstractElasticsearchProcessor {
+
+ static final Relationship REL_SUCCESS = new
Relationship.Builder().name("success")
+ .description("All FlowFiles that are read from Elasticsearch
are routed to this relationship").build();
+
+ static final Relationship REL_FAILURE = new
Relationship.Builder().name("failure")
+ .description("All FlowFiles that cannot be read from
Elasticsearch are routed to this relationship").build();
+
+ static final Relationship REL_RETRY = new
Relationship.Builder().name("retry")
+ .description("A FlowFile is routed to this relationship if the
document cannot be fetched but attempting the operation again may succeed")
+ .build();
+
+ public static final PropertyDescriptor DOC_ID = new
PropertyDescriptor.Builder()
+ .name("Document Identifier")
+ .description("The name of the attribute containing the
identifier for each FlowFile")
+ .required(true)
+ .expressionLanguageSupported(true)
+ .addValidator(StandardValidators.NON_EMPTY_VALIDATOR)
+ .build();
+
+ public static final PropertyDescriptor INDEX = new
PropertyDescriptor.Builder()
+ .name("Index")
+ .description("The name of the index to read from")
+ .required(true)
+ .expressionLanguageSupported(true)
+
.addValidator(StandardValidators.createAttributeExpressionLanguageValidator(
+ AttributeExpression.ResultType.STRING, true))
+ .build();
+
+ public static final PropertyDescriptor TYPE = new
PropertyDescriptor.Builder()
+ .name("Type")
+ .description("The type of this document (used by Elasticsearch
for indexing and searching)")
+ .required(true)
+ .expressionLanguageSupported(true)
+
.addValidator(StandardValidators.createAttributeExpressionLanguageValidator(
+ AttributeExpression.ResultType.STRING, true))
+ .build();
+
+
+ @Override
+ public Set<Relationship> getRelationships() {
+ final Set<Relationship> relationships = new HashSet<>();
+ relationships.add(REL_SUCCESS);
+ relationships.add(REL_FAILURE);
+ relationships.add(REL_RETRY);
+ return Collections.unmodifiableSet(relationships);
+ }
+
+ @Override
+ public final List<PropertyDescriptor>
getSupportedPropertyDescriptors() {
+ final List<PropertyDescriptor> descriptors = new ArrayList<>();
+ descriptors.add(CLUSTER_NAME);
+ descriptors.add(HOSTS);
+ descriptors.add(PROP_SSL_CONTEXT_SERVICE);
+ descriptors.add(PROP_SHIELD_LOCATION);
+ descriptors.add(PING_TIMEOUT);
+ descriptors.add(SAMPLER_INTERVAL);
+ descriptors.add(DOC_ID);
+ descriptors.add(INDEX);
+ descriptors.add(TYPE);
+
+ return Collections.unmodifiableList(descriptors);
+ }
+
+
+ @Override
+ public void onTrigger(final ProcessContext context, final
ProcessSession session) throws ProcessException {
+
+ FlowFile flowFile = session.get();
+ if (flowFile == null) {
+ return;
+ }
+
+ // Create the client if one does not already exist
+ createClient(context);
+
+ final String index =
context.getProperty(INDEX).evaluateAttributeExpressions(flowFile).getValue();
+ final String docId =
context.getProperty(DOC_ID).evaluateAttributeExpressions(flowFile).getValue();
+ final String docType =
context.getProperty(TYPE).evaluateAttributeExpressions(flowFile).getValue();
+
+ final ProcessorLog logger = getLogger();
+ try {
+
+ logger.debug("Fetching {}/{}/{} from Elasticsearch", new
Object[]{index, docType, docId});
+ final GetResponse getResponse =
+ esClient.get().prepareGet(index, docType,
docId).execute().actionGet();
+
+ if (getResponse == null || !getResponse.isExists()) {
+ logger.warn("Failed to read {}/{}/{} from Elasticsearch:
Document not found",
+ new Object[]{index, docType, docId});
+ session.transfer(flowFile, REL_RETRY);
+ context.yield();
--- End diff --
Will change to yield. We would want to retry on not found in case NiFi gets
the document ID but the ES index has not yet been updated to reflect the
addition of the document (i.e. race condition)
---
If your project is set up for it, you can reply to this email and have your
reply appear on GitHub as well. If your project does not have this feature
enabled and wishes so, or if the feature is enabled but not working, please
contact infrastructure at [email protected] or file a JIRA ticket
with INFRA.
---
