<!DOCTYPE html>
<html lang="en">
    <!--
      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.
    -->
    <head>
        <meta charset="utf-8" />
        <title>ConsumeKafka</title>
        <link rel="stylesheet" href="../../../../../css/component-usage.css" type="text/css" />
    </head>

    <body>
        <h2>Description</h2>
        <p>
            This Processor polls <a href="http://kafka.apache.org/">Apache Kafka</a>
            for data using KafkaConsumer API available with Kafka 1.0. When a message is received 
            from Kafka, the message will be deserialized using the configured Record Reader, and then
            written to a FlowFile by serializing the message with the configured Record Writer.
        </p>


        <h2>Security Configuration:</h2>
        <p>
            The Security Protocol property allows the user to specify the protocol for communicating
            with the Kafka broker. The following sections describe each of the protocols in further detail.
        </p>
        <h3>PLAINTEXT</h3>
        <p>
            This option provides an unsecured connection to the broker, with no client authentication and no encryption.
            In order to use this option the broker must be configured with a listener of the form:
        <pre>
    PLAINTEXT://host.name:port
            </pre>
        </p>
        <h3>SSL</h3>
        <p>
            This option provides an encrypted connection to the broker, with optional client authentication. In order
            to use this option the broker must be configured with a listener of the form:
        <pre>
    SSL://host.name:port
            </pre>
        In addition, the processor must have an SSL Context Service selected.
        </p>
        <p>
            If the broker specifies ssl.client.auth=none, or does not specify ssl.client.auth, then the client will
            not be required to present a certificate. In this case, the SSL Context Service selected may specify only
            a truststore containing the public key of the certificate authority used to sign the broker's key.
        </p>
        <p>
            If the broker specifies ssl.client.auth=required then the client will be required to present a certificate.
            In this case, the SSL Context Service must also specify a keystore containing a client key, in addition to
            a truststore as described above.
        </p>
        <h3>SASL_PLAINTEXT</h3>
        <p>
            This option uses SASL with a PLAINTEXT transport layer to authenticate to the broker. In order to use this
            option the broker must be configured with a listener of the form:
        <pre>
    SASL_PLAINTEXT://host.name:port
            </pre>
        In addition, the Kerberos Service Name must be specified in the processor.
        </p>
        <h4>SASL_PLAINTEXT - GSSAPI</h4>
        <p>
            If the SASL mechanism is GSSAPI, then the client must provide a JAAS configuration to authenticate. The
            JAAS configuration can be provided by specifying the java.security.auth.login.config system property in
            NiFi's bootstrap.conf, such as:
        <pre>
    java.arg.16=-Djava.security.auth.login.config=/path/to/kafka_client_jaas.conf
            </pre>
        </p>
        <p>
            An example of the JAAS config file would be the following:
        <pre>
    KafkaClient {
        com.sun.security.auth.module.Krb5LoginModule required
        useKeyTab=true
        storeKey=true
        keyTab="/path/to/nifi.keytab"
        serviceName="kafka"
        principal="nifi@YOURREALM.COM";
    };
            </pre>
        <b>NOTE:</b> The serviceName in the JAAS file must match the Kerberos Service Name in the processor.
        </p>
        <p>
            Alternatively, the JAAS
            configuration when using GSSAPI can be provided by specifying the Kerberos Principal and Kerberos Keytab
            directly in the processor properties. This will dynamically create a JAAS configuration like above, and
            will take precedence over the java.security.auth.login.config system property.
        </p>
        <h4>SASL_PLAINTEXT - PLAIN</h4>
        <p>
            If the SASL mechanism is PLAIN, then client must provide a JAAS configuration to authenticate, but
            the JAAS configuration must use Kafka's PlainLoginModule. An example of the JAAS config file would
            be the following:
        <pre>
    KafkaClient {
      org.apache.kafka.common.security.plain.PlainLoginModule required
      username="nifi"
      password="nifi-password";
    };
            </pre>
        </p>
        <p>
            <b>NOTE:</b> It is not recommended to use a SASL mechanism of PLAIN with SASL_PLAINTEXT, as it would transmit
            the username and password unencrypted.
        </p>
        <p>
            <b>NOTE:</b> Using the PlainLoginModule will cause it be registered in the JVM's static list of Providers, making
            it visible to components in other NARs that may access the providers. There is currently a known issue
            where Kafka processors using the PlainLoginModule will cause HDFS processors with Keberos to no longer work.
        </p>
        <h3>SASL_SSL</h3>
        <p>
            This option uses SASL with an SSL/TLS transport layer to authenticate to the broker. In order to use this
            option the broker must be configured with a listener of the form:
        <pre>
    SASL_SSL://host.name:port
            </pre>
        </p>
        <p>
            See the SASL_PLAINTEXT section for a description of how to provide the proper JAAS configuration
            depending on the SASL mechanism (GSSAPI or PLAIN).
        </p>
        <p>
            See the SSL section for a description of how to configure the SSL Context Service based on the
            ssl.client.auth property.
        </p>

    </body>
</html>