.. _cloud-monitoring-lag:

Monitoring Consumer Lag
=======================

You can monitor consumer lag with |ccloud| using the methods described in this document.

.. contents::
        :local:

Monitor Offset Lag via Java Client Metrics
------------------------------------------

You can monitor the ``records-lag-max`` metric from the :ref:`Java consumer <fetch-metrics-kafka>`.

Monitor Consumer Latency via Client Interceptors
------------------------------------------------

You can use :ref:`control_center` to track consumer latency and more.

Monitor Offset Lag via Broker APIs
----------------------------------

You can also get offsets from the brokers. This section assumes that you
have |ccloud| CLI installed or can copy the same properties generates in
``~/ccloud/config``.

Prerequisites
    .. include:: ../connect/includes/installation.rst
        :start-line: 2
        :end-line: 5

    - |cp| is :ref:`installed <installing_cp>`

#. Comment out the request time out in the |ccloud| config
   (``~/ccloud/config``). This line prevents the |ccloud| CLI commands from
   waiting too long before giving up on errors but conflicts with other
   settings for this use case.

   .. code:: bash

        #request.timeout.ms=20000

#. Set the ``BOOTSTRAP_SERVERS`` variable to the broker list value that was provided when you signed up. You can find this
   value in ``~/.ccloud/config`` or by clicking **Client config** from the |ccloud| web interface.

   .. code:: bash

        $ BOOTSTRAP_SERVERS="SASL_SSL://<bootstrap-server1>, <bootstrap-server2>, <bootstrap-server3>"

#. From the |cp| installation home, list the consumer groups:

   .. code:: bash

        $ ./bin/kafka-consumer-groups --bootstrap-server ${BOOTSTRAP_SERVERS} --command-config \
          ~/.ccloud/config --list  _confluent-healthcheck  example-group

#. For each consumer group, check its offsets using this command. This command only shows information about consumers that
   use the Java consumer API (i.e., non-|zk|-based consumers).

   .. code:: bash

        $ ./bin/kafka-consumer-groups --bootstrap-server ${BOOTSTRAP_SERVERS} \
          --command-config ~/.ccloud/config --describe --group _confluent-healthcheck

   Your output should resemble:

   .. code:: bash

            TOPIC                          PARTITION  CURRENT-OFFSET  LOG-END-OFFSET  LAG        CONSUMER-ID                                       HOST                           CLIENT-ID
            _confluent-healthcheck         0          13164704        13164773        69         healthcheck-agent-bf8d1655-63a6-4061-b680-0f11cdf182e5/100.96.67.0                   healthcheck-agent
            _confluent-healthcheck         1          13161581        13161650        69         healthcheck-agent-bf8d1655-63a6-4061-b680-0f11cdf182e5/100.96.67.0                   healthcheck-agent
            _confluent-healthcheck         2          12229509        12229578        69         healthcheck-agent-bf8d1655-63a6-4061-b680-0f11cdf182e5/100.96.67.0                   healthcheck-agent
            _confluent-healthcheck         3          86              86              0          healthcheck-agent-bf8d1655-63a6-4061-b680-0f11cdf182e5/100.96.67.0                   healthcheck-agent
            ...

   The fourth column shows the lag, the difference between the last
   committed offset and the latest offset in the log.