.. _use-jmx-monitor-docker-deployments:

Monitoring |cp| Docker Deployments using JMX
--------------------------------------------

You can monitor |cp| Docker deployments by using Java Management Extensions
(JMX).

Configure Environment
"""""""""""""""""""""

To use JMX with Docker containers, set the following properties:

.. codewithvars:: bash

    java.rmi.server.hostname=<JMX_HOSTNAME>
    com.sun.management.jmxremote.local.only=false
    com.sun.management.jmxremote.rmi.port=<JMX_PORT>
    com.sun.management.jmxremote.port=<JMX_PORT>

Note about ``hostname``:
  The JMX client needs to be able to connect to ``java.rmi.server.hostname``.
  The default for bridged network is the bridged IP so you will only be able to connect from another Docker container.
  For host network, this is the IP that the hostname on the host resolves to.

  The hostname is set to ``hostname -i`` in the Docker container. If you have more that one network configured for the container, ``hostname -i`` gives you all the IPs, the default is to pick the first IP (or network).

Configure Security
""""""""""""""""""

To set security on JMX, you can follow the SSL and authentication sections in
this guide:
https://docs.oracle.com/javase/8/docs/technotes/guides/management/agent.html.

Configure Kafka and |zk|
""""""""""""""""""""""""

Settings
````````

Use the following environment variables to configure JMX monitoring for |ak| and |zk|.

``KAFKA_JMX_PORT``
    JMX Port.

``KAFKA_JMX_OPTS``
    JMX options. Use this variable to override the default JMX options. The default options are set as follows:
    
    .. codewithvars:: bash

      -Djava.rmi.server.hostname=127.0.0.1 -Dcom.sun.management.jmxremote=true -Dcom.sun.management.jmxremote.authenticate=false  -Dcom.sun.management.jmxremote.ssl=false

``KAFKA_JMX_HOSTNAME``
    Hostname associated with locally created remote objects.

Launching Kafka and |zk| with JMX Enabled
`````````````````````````````````````````

The steps for launching Kafka and |zk| with JMX enabled are the same as shown in the :ref:`ce-docker-quickstart`, with the only difference being that you set ``KAFKA_JMX_PORT`` and ``KAFKA_JMX_HOSTNAME`` for both.  Here are examples of the Docker ``run`` commands for each service:

.. codewithvars:: bash

  docker run -d \
    --name=zk-jmx \
    --net=host \
    -e ZOOKEEPER_TICK_TIME=2000 \
    -e ZOOKEEPER_CLIENT_PORT=32181 \
    -e KAFKA_JMX_PORT=39999 \
    -e KAFKA_JMX_HOSTNAME=`docker-machine ip confluent`
    confluentinc/cp-zookeeper:|release|

  docker run -d \
    --name=kafka-jmx \
    --net=host \
    -e KAFKA_BROKER_ID=1 \
    -e KAFKA_ZOOKEEPER_CONNECT=localhost:32181/jmx \
    -e KAFKA_ADVERTISED_LISTENERS=PLAINTEXT://localhost:39092 \
    -e KAFKA_JMX_PORT=49999 \
    -e KAFKA_JMX_HOSTNAME=`docker-machine ip confluent` \
    -e KAFKA_OFFSETS_TOPIC_REPLICATION_FACTOR=1 \
    confluentinc/cp-kafka:|release|


Tip: The examples above for KAFKA_JMX_HOSTNAME environment variable assume you have a Docker machine named "confluent".  Substitute this with your Docker machine name where appropriate.

.. _jmx-overrides-for-cp:

Configure other |cp| components
"""""""""""""""""""""""""""""""

Authentication is disabled for JMX by default in |ak|. The default JMX configuration binds an unauthenticated JMX interface to all network interfaces. You must use environment variables to override this default.

Use the following environment variables to override the default JMX options for |cp| components. 

========== ========================
Component  Environment Variable
========== ========================
|c3|       CONTROL_CENTER_JMX_OPTS
|crest|    KAFKAREST_JMX_OPTS
KSQL       KSQL_JMX_OPTS
Rebalancer REBALANCER_JMX_OPTS
|sr|       SCHEMA_REGISTRY_JMX_OPTS
========== ========================