Prometheus metrics exporter for Flask
Project description
Prometheus Flask exporter
=========================
|Travis| |PyPI| |PyPI| |Coverage Status| |Code Climate|
This library provides HTTP request metrics to export into
`Prometheus <https://prometheus.io/>`__. It can also track method
invocations using convenient functions.
Usage
-----
.. code:: python
from flask import Flask, request
from prometheus_flask_exporter import PrometheusMetrics
app = Flask(__name__)
metrics = PrometheusMetrics(app)
# static information as metric
metrics.info('app_info', 'Application info', version='1.0.3')
@app.route('/')
def main():
pass # requests tracked by default
@app.route('/skip')
@metrics.do_not_track()
def skip():
pass # default metrics are not collected
@app.route('/<item_type>')
@metrics.do_not_track()
@metrics.counter('invocation_by_type', 'Number of invocations by type',
labels={'item_type': lambda: request.view_args['type']})
def by_type(item_type):
pass # only the counter is collected, not the default metrics
@app.route('/long-running')
@metrics.gauge('in_progress', 'Long running requests in progress')
def long_running():
pass
@app.route('/status/<int:status>')
@metrics.do_not_track()
@metrics.summary('requests_by_status', 'Request latencies by status',
labels={'status': lambda r: r.status_code})
@metrics.histogram('requests_by_status_and_path', 'Request latencies by status and path',
labels={'status': lambda r: r.status_code, 'path': lambda: request.path})
def echo_status(status):
return 'Status: %s' % status, status
Default metrics
---------------
The following metrics are exported by default (unless the
``export_defaults`` is set to ``False``).
- ``flask_http_request_duration_seconds`` (Histogram)
Labels: ``method``, ``path`` and ``status``.
Flask HTTP request duration in seconds for all Flask requests.
- ``flask_http_request_total`` (Counter)
Labels: ``method`` and ``status``. Total number of HTTP requests for
all Flask requests.
- ``flask_exporter_info`` (Gauge)
Information about the Prometheus Flask exporter itself (e.g.
``version``).
Configuration
-------------
By default, the metrics are exposed on the same Flask application on the
``/metrics`` endpoint and using the core Prometheus registry. If this
doesn't suit your needs, set the ``path`` argument to ``None`` and/or
the ``export_defaults`` argument to ``False`` plus change the
``registry`` argument if needed. The ``group_by_endpoint`` constructor
flag makes the default request duration metric tracked by endpoint
(function) instead of URI path.
The ``register_endpoint`` allows exposing the metrics endpoint on a
specific path. It also allows passing in a Flask application to register
it on but defaults to the main one if not defined.
Similarly, the ``start_http_server`` allows exposing the endpoint on an
independent Flask application on a selected HTTP port. It also supports
overriding the endpoint's path and the HTTP listen address.
Labels
------
When defining labels for metrics on functions, the following values are
supported in the dictionary:
- A simple static value
- A no-argument callable
- A single argument callable that will receive the Flask response as
the argument
Label values are evaluated within the request context.
Application information
-----------------------
The ``PrometheusMetrics.info(..)`` method provides a way to expose
information as a ``Gauge`` metric, the application version for example.
The metric is returned from the method to allow changing its value from
the default ``1``:
.. code:: python
metrics = PrometheusMetrics(app)
info = metrics.info('dynamic_info', 'Something dynamic')
...
info.set(42.1)
Examples
--------
See some simple examples visualized on a Grafana dashboard by running
the demo in the
`examples/sample-signals <https://github.com/rycus86/prometheus_flask_exporter/tree/master/examples/wsgi>`__
folder.
.. figure:: examples/sample-signals/dashboard.png
:alt: Example dashboard
Example dashboard
Debug mode
----------
Please note, that changes being live-reloaded, when running the Flask
app with ``debug=True``, are not going to be reflected in the metrics.
See https://github.com/rycus86/prometheus_flask_exporter/issues/4 for
more details.
WSGI
----
Getting accurate metrics for WSGI apps might require a bit more setup.
See a working sample app in the ``examples`` folder, and also the
`prometheus\_flask\_exporter#5 <https://github.com/rycus86/prometheus_flask_exporter/issues/5>`__
issue.
License
-------
MIT
.. |Travis| image:: https://img.shields.io/travis/rycus86/prometheus_flask_exporter.svg
:target: https://travis-ci.org/rycus86/prometheus_flask_exporter
.. |PyPI| image:: https://img.shields.io/pypi/v/prometheus-flask-exporter.svg
:target: https://pypi.python.org/pypi/prometheus-flask-exporter
.. |PyPI| image:: https://img.shields.io/pypi/pyversions/prometheus-flask-exporter.svg
:target: https://pypi.python.org/pypi/prometheus-flask-exporter
.. |Coverage Status| image:: https://coveralls.io/repos/github/rycus86/prometheus_flask_exporter/badge.svg?branch=master
:target: https://coveralls.io/github/rycus86/prometheus_flask_exporter?branch=master
.. |Code Climate| image:: https://codeclimate.com/github/rycus86/prometheus_flask_exporter/badges/gpa.svg
:target: https://codeclimate.com/github/rycus86/prometheus_flask_exporter
=========================
|Travis| |PyPI| |PyPI| |Coverage Status| |Code Climate|
This library provides HTTP request metrics to export into
`Prometheus <https://prometheus.io/>`__. It can also track method
invocations using convenient functions.
Usage
-----
.. code:: python
from flask import Flask, request
from prometheus_flask_exporter import PrometheusMetrics
app = Flask(__name__)
metrics = PrometheusMetrics(app)
# static information as metric
metrics.info('app_info', 'Application info', version='1.0.3')
@app.route('/')
def main():
pass # requests tracked by default
@app.route('/skip')
@metrics.do_not_track()
def skip():
pass # default metrics are not collected
@app.route('/<item_type>')
@metrics.do_not_track()
@metrics.counter('invocation_by_type', 'Number of invocations by type',
labels={'item_type': lambda: request.view_args['type']})
def by_type(item_type):
pass # only the counter is collected, not the default metrics
@app.route('/long-running')
@metrics.gauge('in_progress', 'Long running requests in progress')
def long_running():
pass
@app.route('/status/<int:status>')
@metrics.do_not_track()
@metrics.summary('requests_by_status', 'Request latencies by status',
labels={'status': lambda r: r.status_code})
@metrics.histogram('requests_by_status_and_path', 'Request latencies by status and path',
labels={'status': lambda r: r.status_code, 'path': lambda: request.path})
def echo_status(status):
return 'Status: %s' % status, status
Default metrics
---------------
The following metrics are exported by default (unless the
``export_defaults`` is set to ``False``).
- ``flask_http_request_duration_seconds`` (Histogram)
Labels: ``method``, ``path`` and ``status``.
Flask HTTP request duration in seconds for all Flask requests.
- ``flask_http_request_total`` (Counter)
Labels: ``method`` and ``status``. Total number of HTTP requests for
all Flask requests.
- ``flask_exporter_info`` (Gauge)
Information about the Prometheus Flask exporter itself (e.g.
``version``).
Configuration
-------------
By default, the metrics are exposed on the same Flask application on the
``/metrics`` endpoint and using the core Prometheus registry. If this
doesn't suit your needs, set the ``path`` argument to ``None`` and/or
the ``export_defaults`` argument to ``False`` plus change the
``registry`` argument if needed. The ``group_by_endpoint`` constructor
flag makes the default request duration metric tracked by endpoint
(function) instead of URI path.
The ``register_endpoint`` allows exposing the metrics endpoint on a
specific path. It also allows passing in a Flask application to register
it on but defaults to the main one if not defined.
Similarly, the ``start_http_server`` allows exposing the endpoint on an
independent Flask application on a selected HTTP port. It also supports
overriding the endpoint's path and the HTTP listen address.
Labels
------
When defining labels for metrics on functions, the following values are
supported in the dictionary:
- A simple static value
- A no-argument callable
- A single argument callable that will receive the Flask response as
the argument
Label values are evaluated within the request context.
Application information
-----------------------
The ``PrometheusMetrics.info(..)`` method provides a way to expose
information as a ``Gauge`` metric, the application version for example.
The metric is returned from the method to allow changing its value from
the default ``1``:
.. code:: python
metrics = PrometheusMetrics(app)
info = metrics.info('dynamic_info', 'Something dynamic')
...
info.set(42.1)
Examples
--------
See some simple examples visualized on a Grafana dashboard by running
the demo in the
`examples/sample-signals <https://github.com/rycus86/prometheus_flask_exporter/tree/master/examples/wsgi>`__
folder.
.. figure:: examples/sample-signals/dashboard.png
:alt: Example dashboard
Example dashboard
Debug mode
----------
Please note, that changes being live-reloaded, when running the Flask
app with ``debug=True``, are not going to be reflected in the metrics.
See https://github.com/rycus86/prometheus_flask_exporter/issues/4 for
more details.
WSGI
----
Getting accurate metrics for WSGI apps might require a bit more setup.
See a working sample app in the ``examples`` folder, and also the
`prometheus\_flask\_exporter#5 <https://github.com/rycus86/prometheus_flask_exporter/issues/5>`__
issue.
License
-------
MIT
.. |Travis| image:: https://img.shields.io/travis/rycus86/prometheus_flask_exporter.svg
:target: https://travis-ci.org/rycus86/prometheus_flask_exporter
.. |PyPI| image:: https://img.shields.io/pypi/v/prometheus-flask-exporter.svg
:target: https://pypi.python.org/pypi/prometheus-flask-exporter
.. |PyPI| image:: https://img.shields.io/pypi/pyversions/prometheus-flask-exporter.svg
:target: https://pypi.python.org/pypi/prometheus-flask-exporter
.. |Coverage Status| image:: https://coveralls.io/repos/github/rycus86/prometheus_flask_exporter/badge.svg?branch=master
:target: https://coveralls.io/github/rycus86/prometheus_flask_exporter?branch=master
.. |Code Climate| image:: https://codeclimate.com/github/rycus86/prometheus_flask_exporter/badges/gpa.svg
:target: https://codeclimate.com/github/rycus86/prometheus_flask_exporter
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