granthenke commented on a change in pull request #3732: NIFI-6662: Adding Kudu 
Lookup Service
URL: https://github.com/apache/nifi/pull/3732#discussion_r324363969
 
 

 ##########
 File path: 
nifi-nar-bundles/nifi-kudu-bundle/nifi-kudu-controller-service/src/main/java/org/apache/nifi/controller/kudu/KuduLookupService.java
 ##########
 @@ -0,0 +1,392 @@
+/*
+ * 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.controller.kudu;
+
+import org.apache.kudu.ColumnSchema;
+import org.apache.kudu.Schema;
+import org.apache.kudu.Type;
+import org.apache.kudu.client.AsyncKuduClient;
+import org.apache.kudu.client.KuduClient;
+import org.apache.kudu.client.KuduException;
+import org.apache.kudu.client.KuduPredicate;
+import org.apache.kudu.client.KuduScanner;
+import org.apache.kudu.client.KuduTable;
+import org.apache.kudu.client.RowResult;
+import org.apache.kudu.client.RowResultIterator;
+import org.apache.nifi.annotation.documentation.CapabilityDescription;
+import org.apache.nifi.annotation.documentation.Tags;
+import org.apache.nifi.annotation.lifecycle.OnDisabled;
+import org.apache.nifi.annotation.lifecycle.OnEnabled;
+import org.apache.nifi.components.PropertyDescriptor;
+import org.apache.nifi.controller.AbstractControllerService;
+import org.apache.nifi.controller.ConfigurationContext;
+import org.apache.nifi.controller.ControllerServiceInitializationContext;
+import org.apache.nifi.expression.ExpressionLanguageScope;
+import org.apache.nifi.kerberos.KerberosCredentialsService;
+import org.apache.nifi.lookup.LookupFailureException;
+import org.apache.nifi.lookup.RecordLookupService;
+import org.apache.nifi.processor.util.StandardValidators;
+import org.apache.nifi.reporting.InitializationException;
+import org.apache.nifi.security.krb.KerberosAction;
+import org.apache.nifi.security.krb.KerberosKeytabUser;
+import org.apache.nifi.security.krb.KerberosUser;
+import org.apache.nifi.serialization.SimpleRecordSchema;
+import org.apache.nifi.serialization.record.MapRecord;
+import org.apache.nifi.serialization.record.Record;
+import org.apache.nifi.serialization.record.RecordField;
+import org.apache.nifi.serialization.record.RecordFieldType;
+import org.apache.nifi.serialization.record.RecordSchema;
+
+import javax.security.auth.login.LoginException;
+import java.math.BigDecimal;
+import java.sql.Timestamp;
+import java.util.ArrayList;
+import java.util.Arrays;
+import java.util.Base64;
+import java.util.Collections;
+import java.util.HashMap;
+import java.util.HashSet;
+import java.util.List;
+import java.util.Map;
+import java.util.Optional;
+import java.util.Set;
+import java.util.concurrent.TimeUnit;
+import java.util.stream.Collectors;
+
+
+@CapabilityDescription("Lookup a record from Kudu Server associated with the 
specified key. Binary columns are base64 encoded")
+@Tags({"lookup", "enrich", "key", "value", "kudu"})
+public class KuduLookupService extends AbstractControllerService implements 
RecordLookupService {
+
+    static final PropertyDescriptor KUDU_MASTERS = new 
PropertyDescriptor.Builder()
+            .name("Kudu Masters")
+            .description("Comma separated addresses of the Kudu masters to 
connect to.")
+            .required(true)
+            .addValidator(StandardValidators.NON_EMPTY_VALIDATOR)
+            
.expressionLanguageSupported(ExpressionLanguageScope.VARIABLE_REGISTRY)
+            .build();
+
+    static final PropertyDescriptor KERBEROS_CREDENTIALS_SERVICE = new 
PropertyDescriptor.Builder()
+            .name("kerberos-credentials-service")
+            .displayName("Kerberos Credentials Service")
+            .description("Specifies the Kerberos Credentials to use for 
authentication")
+            .required(false)
+            .identifiesControllerService(KerberosCredentialsService.class)
+            .build();
+
+    static final PropertyDescriptor KUDU_OPERATION_TIMEOUT_MS = new 
PropertyDescriptor.Builder()
+            .name("kudu-operations-timeout-ms")
+            .displayName("Kudu Operation Timeout")
+            .description("Default timeout used for user operations (using 
sessions and scanners)")
+            .required(false)
+            .defaultValue(AsyncKuduClient.DEFAULT_OPERATION_TIMEOUT_MS + "ms")
+            .addValidator(StandardValidators.TIME_PERIOD_VALIDATOR)
+            
.expressionLanguageSupported(ExpressionLanguageScope.VARIABLE_REGISTRY)
+            .build();
+
+    static final PropertyDescriptor KUDU_KEEP_ALIVE_PERIOD_TIMEOUT_MS = new 
PropertyDescriptor.Builder()
+            .name("kudu-keep-alive-period-timeout-ms")
+            .displayName("Kudu Keep Alive Period Timeout")
+            .description("Default timeout used for user operations")
+            .required(false)
+            .defaultValue(AsyncKuduClient.DEFAULT_KEEP_ALIVE_PERIOD_MS + "ms")
+            .addValidator(StandardValidators.TIME_PERIOD_VALIDATOR)
+            
.expressionLanguageSupported(ExpressionLanguageScope.VARIABLE_REGISTRY)
+            .build();
+
+    public static final PropertyDescriptor TABLE_NAME = new 
PropertyDescriptor.Builder()
+            .name("table-name")
+            .displayName("Table Name")
+            .description("Name of the table to access.")
+            .required(true)
+            .defaultValue("default")
+            .addValidator(StandardValidators.NON_BLANK_VALIDATOR)
+            
.expressionLanguageSupported(ExpressionLanguageScope.VARIABLE_REGISTRY)
+            .build();
+
+    static final PropertyDescriptor RETURN_COLUMNS = new 
PropertyDescriptor.Builder()
+            .name("kudu-lu-return-cols")
+            .displayName("Columns")
+            .description("A comma-separated list of columns to return when 
scanning. To return all columns set to \"*\"")
+            .required(true)
+            .defaultValue("*")
+            .addValidator(StandardValidators.NON_BLANK_VALIDATOR)
+            
.expressionLanguageSupported(ExpressionLanguageScope.VARIABLE_REGISTRY)
+            .build();
+
+
+    protected List<PropertyDescriptor> properties;
+
+    protected KerberosCredentialsService credentialsService;
+    private volatile KerberosUser kerberosUser;
+
+    protected String kuduMasters;
+    protected KuduClient kuduClient;
+    protected volatile String tableName;
+    protected volatile KuduTable table;
+    protected volatile List<String> columnNames;
+
+    protected volatile RecordSchema resultSchema;
+    protected volatile Schema tableSchema;
+
+    @Override
+    protected void init(final ControllerServiceInitializationContext context) {
+        final List<PropertyDescriptor> properties = new ArrayList<>();
+        properties.add(KUDU_MASTERS);
+        properties.add(KERBEROS_CREDENTIALS_SERVICE);
+        properties.add(KUDU_OPERATION_TIMEOUT_MS);
+        properties.add(KUDU_KEEP_ALIVE_PERIOD_TIMEOUT_MS);
+        properties.add(TABLE_NAME);
+        properties.add(RETURN_COLUMNS);
+        addProperties(properties);
+        this.properties = Collections.unmodifiableList(properties);
+    }
+
+    protected void addProperties(List<PropertyDescriptor> properties) {
+    }
+
+    protected void createKuduClient(ConfigurationContext context) throws 
LoginException {
+        final String kuduMasters = 
context.getProperty(KUDU_MASTERS).evaluateAttributeExpressions().getValue();
+        final KerberosCredentialsService credentialsService = 
context.getProperty(KERBEROS_CREDENTIALS_SERVICE).asControllerService(KerberosCredentialsService.class);
+
+        if (credentialsService == null) {
+            return;
+        }
+
+        final String keytab = credentialsService.getKeytab();
+        final String principal = credentialsService.getPrincipal();
+        kerberosUser = loginKerberosUser(principal, keytab);
+
+        final KerberosAction<KuduClient> kerberosAction = new 
KerberosAction<>(kerberosUser, () -> buildClient(kuduMasters, context), 
getLogger());
+        this.kuduClient = kerberosAction.execute();
+    }
+    protected KerberosUser loginKerberosUser(final String principal, final 
String keytab) throws LoginException {
+        final KerberosUser kerberosUser = new KerberosKeytabUser(principal, 
keytab);
+        kerberosUser.login();
+        return kerberosUser;
+    }
+    protected KuduClient buildClient(final String masters, final 
ConfigurationContext context) {
+        final Integer operationTimeout = 
context.getProperty(KUDU_OPERATION_TIMEOUT_MS).asTimePeriod(TimeUnit.MILLISECONDS).intValue();
+        final Integer adminOperationTimeout = 
context.getProperty(KUDU_KEEP_ALIVE_PERIOD_TIMEOUT_MS).asTimePeriod(TimeUnit.MILLISECONDS).intValue();
+
+        return new KuduClient.KuduClientBuilder(masters)
+                .defaultOperationTimeoutMs(operationTimeout)
+                .defaultSocketReadTimeoutMs(adminOperationTimeout)
+                .build();
+    }
+    /**
+     * Establish a connection to a Kudu cluster.
+     * @param context the configuration context
+     * @throws InitializationException if unable to connect a Kudu cluster
+     */
+    @OnEnabled
+    public void onEnabled(final ConfigurationContext context) throws 
InitializationException {
+
+        try {
+            kuduMasters = 
context.getProperty(KUDU_MASTERS).evaluateAttributeExpressions().getValue();
+            credentialsService = 
context.getProperty(KERBEROS_CREDENTIALS_SERVICE).asControllerService(KerberosCredentialsService.class);
+
+            if (kuduClient == null) {
+                getLogger().debug("Setting up Kudu connection...");
+
+                createKuduClient(context);
+                getLogger().debug("Kudu connection successfully initialized");
+            }
+        } catch(Exception ex){
+            getLogger().error("Exception occurred while interacting with Kudu 
due to " + ex.getMessage(), ex);
+            throw new InitializationException(ex);
+        }
+
+        tableName = 
context.getProperty(TABLE_NAME).evaluateAttributeExpressions().getValue();
+        try {
+            table = kuduClient.openTable(tableName);
+            tableSchema = table.getSchema();
+            columnNames = 
getColumns(context.getProperty(RETURN_COLUMNS).getValue());
+
+            //Result Schema
+            resultSchema = kuduSchemaToNiFiSchema(tableSchema, columnNames);
+
+        } catch (KuduException e) {
+            throw new IllegalArgumentException(e);
+        }
+    }
+
+    @Override
+    public Set<String> getRequiredKeys() {
+        return new HashSet<>();
+    }
+
+    @Override
+    protected List<PropertyDescriptor> getSupportedPropertyDescriptors() {
+        return properties;
+    }
+    @Override
+    public Optional<Record> lookup(Map<String, Object> coordinates) throws 
LookupFailureException {
+
+        //Scanner
+        KuduScanner.KuduScannerBuilder builder = 
kuduClient.newScannerBuilder(table);
+
+        builder.setProjectedColumnNames(columnNames);
+
+        coordinates.forEach((key,value)->
+                
builder.addPredicate(createPredicate(tableSchema.getColumn(key), 
KuduPredicate.ComparisonOp.EQUAL, value))
+        );
+
+        KuduScanner kuduScanner = builder.build();
+
+        //run lookup
+        try {
+            if (kuduScanner.hasMoreRows()) {
+                RowResultIterator resultIterator = kuduScanner.nextRows();
+                final Map<String, Object> values = new HashMap<>();
+
+                //Only need first row
+                if (resultIterator.hasNext()) {
+                    RowResult result  = resultIterator.next();
+
+                    for(String columnName : columnNames){
+                        values.put(columnName,getObject(result,columnName));
+                    }
+                    return Optional.of(new MapRecord(resultSchema, values));
+                }
+            }
+        } catch (KuduException ex) {
+            throw new LookupFailureException("Failed to lookup from Kudu using 
these coordinates " + coordinates,ex);
+        }
+        //no match
+        return Optional.empty();
+    }
+
+    private KuduPredicate createPredicate(ColumnSchema 
columnSchema,KuduPredicate.ComparisonOp comparisonOp, Object obj){
+        if(obj instanceof Boolean)
+            return KuduPredicate.newComparisonPredicate(columnSchema, 
comparisonOp, (Boolean)obj);
+        else if(obj instanceof Double)
+            return KuduPredicate.newComparisonPredicate(columnSchema, 
comparisonOp, (Double)obj);
+        else if(obj instanceof Float)
+            return KuduPredicate.newComparisonPredicate(columnSchema, 
comparisonOp, (Float)obj);
+        else if(obj instanceof String)
+            return KuduPredicate.newComparisonPredicate(columnSchema, 
comparisonOp, (String)obj);
+        else if(obj instanceof BigDecimal)
+            return KuduPredicate.newComparisonPredicate(columnSchema, 
comparisonOp, (BigDecimal)obj);
+        else if(obj instanceof Long)
+            return KuduPredicate.newComparisonPredicate(columnSchema, 
comparisonOp, (Long)obj);
+        else if(obj instanceof Integer)
+            return KuduPredicate.newComparisonPredicate(columnSchema, 
comparisonOp, (Integer)obj);
+        else if(obj instanceof Timestamp)
+            return KuduPredicate.newComparisonPredicate(columnSchema, 
comparisonOp, (Timestamp) obj);
+        else if(obj instanceof byte[])
+            return KuduPredicate.newComparisonPredicate(columnSchema, 
comparisonOp, (byte[]) obj);
+        else if(obj instanceof Byte)
+            return KuduPredicate.newComparisonPredicate(columnSchema, 
comparisonOp, (Byte) obj);
+        else if(obj instanceof Short)
+            return KuduPredicate.newComparisonPredicate(columnSchema, 
comparisonOp, (Short) obj);
+        else
+            throw new IllegalArgumentException("Unknown object type: 
"+obj.getClass().getCanonicalName());
+    }
+    private List<String> getColumns(String columns){
+        if(columns.equals("*")){
+            return tableSchema
+                    .getColumns()
+                    .stream().map(ColumnSchema::getName)
+                    .collect(Collectors.toList());
+        } else {
+            return Arrays.asList(columns.split(","));
+        }
+    }
+    private RecordSchema kuduSchemaToNiFiSchema(Schema kuduTableSchema, 
List<String> columnNames){
+        final List<RecordField> fields = new ArrayList<>();
+        for(String columnName : columnNames) {
+            ColumnSchema cs = kuduTableSchema.getColumn(columnName);
 
 Review comment:
   Is it worth checkin if the column exists and throwing a clear error here?

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