54 lines
2.1 KiB
ReStructuredText
54 lines
2.1 KiB
ReStructuredText
.. _metrics:
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===============================================
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Emitting metrics from Ironic-Python-Agent (IPA)
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===============================================
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This document describes how to emit metrics from IPA, including timers and
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counters in code to directly emitting hardware metrics from a custom
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HardwareManager.
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Overview
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========
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IPA uses the metrics implementation from ironic-lib, with a few caveats due
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to the dynamic configuration done at lookup time. You cannot cache the metrics
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instance as the MetricsLogger returned will change after lookup if configs
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different than the default setting have been used. This also means that the
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method decorator supported by ironic-lib cannot be used in IPA.
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Using a context manager
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=======================
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Using the context manager is the recommended way for sending metrics that time
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or count sections of code. However, given that you cannot cache the
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MetricsLogger, you have to explicitly call get_metrics_logger() from
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ironic-lib every time. For example::
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from ironic_lib import metrics_utils
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def my_method():
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with metrics_utils.get_metrics_logger(__name__).timer('my_method'):
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return _do_work()
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As a note, these metric collectors do work for custom HardwareManagers as
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well. However, you may want to metric the portions of a method that determine
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compatibility separate from portions of a method that actually do work, in
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order to assure the metrics are relevant and useful on all hardware.
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Explicitly sending metrics
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==========================
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A feature that may be particularly helpful for deployers writing custom
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HardwareManagers is the ability to explicitly send metrics. For instance,
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you could add a cleaning step which would retrieve metrics about a device and
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ship them using the provided metrics library. For example::
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from ironic_lib import metrics_utils
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def my_cleaning_step():
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for name, value in _get_smart_data():
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metrics_utils.get_metrics_logger(__name__).send_gauge(name, value)
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References
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==========
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For more information, please read the source of the metrics module in
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`ironic-lib <http://git.openstack.org/cgit/openstack/ironic-lib/tree/ironic_lib>`_.
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