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<head>
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<title>ConsumeKafka</title>
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<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, this Processor emits a FlowFile where the content of the FlowFile is the value
of the Kafka message.
</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>
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