Adding documentation page on what ElastAlert metrics are being exposed via --prometheus_port configuration flag

CHANGELOG.md

@@ -18,7 +18,7 @@
 - None
 
 ## Other changes
-- None
+- [Docs] Add exposed metrics documentation - [#498](https://github.com/jertel/elastalert2/pull/498) - @thisisxgp
 
 # 2.2.2
 

docs/source/index.rst

@@ -21,6 +21,7 @@ Contents:
  recipes/writing_filters
  recipes/adding_enhancements
  recipes/adding_loaders
+ recipes/exposing_rule_metrics
  recipes/signing_requests
  recipes/faq
 

docs/source/recipes/exposing_rule_metrics.rst

@@ -0,0 +1,58 @@
+.. _exposingrulemetrics:
+
+Exposing Rule Metrics
+=====================
+
+Configuration
+-------------
+Running ElastAlert with ``--prometheus_port`` configuration flag will expose ElastAlert 2 Prometheus metrics on the specified port. Prometheus metrics are disabled by default.
+
+To expose ElastAlert rule metrics on port ``9979`` run the following command:
+
+.. code-block:: console
+
+ $ elastalert --config config.yaml --prometheus_port 9979 
+
+Rule Metrics
+------------
+
+The metrics being exposed are related to the `ElastAlert metadata indices <https://elastalert2.readthedocs.io/en/latest/elastalert_status.html>`_. The exposed metrics are in the `Prometheus text-based format <https://prometheus.io/docs/instrumenting/exposition_formats/#text-based-format>`_. Metrics are of the metric type `counter <https://prometheus.io/docs/concepts/metric_types/#counter>`_ or `gauge <https://prometheus.io/docs/concepts/metric_types/#gauge>`_ and follow the `Prometheus metric naming <https://prometheus.io/docs/practices/naming/>`_. 
+
+In the standard metric definition, the metric names are structured as follows:
+
+.. code-block:: console
+
+ elastalert_{metric}_{unit}
+
+Where:
+
+- ``{metric}`` is a unique name of the metric. For example, ``hits``.
+- ``{unit}`` is the unit of measurement of the metric value. For example, ``total`` is a counter type metric and ``created`` is a gauge type metric.
+
+All metrics except ``elastalert_errors_{unit}`` have values that apply to a particular rule name. In the exported metrics, these can be identified using the ``rule_name`` `Prometheus label <https://prometheus.io/docs/concepts/data_model/#metric-names-and-labels>`_.
+
+Find below all available metrics:
+
++---------------------------------------+-----------------+---------------------------+---------------+
+| METRIC | Type | Description | Label |
++=======================================+=================+===========================+===============+
+| ``elastalert_scrapes_{unit}`` | Counter, Gauge | Number of scrapes | ``rule_name`` |
++---------------------------------------+-----------------+---------------------------+---------------+
+| ``elastalert_hits_{unit}`` | Counter, Gauge | Number of hits | ``rule_name`` |
++---------------------------------------+-----------------+---------------------------+---------------+
+| ``elastalert_matches_{unit}`` | Counter, Gauge | Number of matches | ``rule_name`` |
++---------------------------------------+-----------------+---------------------------+---------------+
+| ``elastalert_time_taken_{unit}`` | Counter, Gauge | Time taken in seconds | ``rule_name`` |
++---------------------------------------+-----------------+---------------------------+---------------+
+| ``elastalert_alerts_sent_{unir}`` | Counter, Gauge | Number of alerts sent | ``rule_name`` |
++---------------------------------------+-----------------+---------------------------+---------------+
+| ``elastalert_alerts_not_sent_{unit}`` | Counter, Gauge | Number of alerts not sent | ``rule_name`` |
++---------------------------------------+-----------------+---------------------------+---------------+
+| ``elastalert_alerts_silenced_{unit}`` | Counter, Gauge | Number of silenced alerts | ``rule_name`` |
++---------------------------------------+-----------------+---------------------------+---------------+
+| ``elastalert_errors_{unit}`` | Counter, Gauge | Number of errors | |
++---------------------------------------+-----------------+---------------------------+---------------+
+
+
+
+

docs/source/running_elastalert.rst

@@ -44,7 +44,7 @@ logs `localhost:9200` instead of the actual ``es_host``:``es_port``.
 ``--pin_rules`` will stop ElastAlert 2 from loading, reloading or removing rules
 based on changes to their config files.
 
-``--prometheus_port`` exposes ElastAlert 2 Prometheus metrics on the specified
+``--prometheus_port`` exposes ElastAlert 2 `Prometheus metrics <https://elastalert2.readthedocs.io/en/latest/recipes/exposing_rule_metrics.html>`_ on the specified
 port. Prometheus metrics disabled by default.
 
 ``--rule <rule.yaml>`` will only run the given rule. The rule file may be a