aioprometheus 18.1.3

A Prometheus Python client library for asyncio-based applications

aioprometheus

aioprometheus is a Prometheus Python client library for asyncio-based applications. It provides metrics collection and serving capabilities, supports multiple data formats and pushing metrics to a gateway.

The project documentation can be found on ReadTheDocs.

Install

$ pip install aioprometheus

Example

#!/usr/bin/env python
'''
This example demonstrates how a single Counter metric collector can be created
and exposed via a HTTP endpoint.
'''
import asyncio
import socket
from aioprometheus import Counter, Service


if __name__ == '__main__':

    def on_timer_expiry(loop, events_collector):
        ''' Update the metric periodically '''
        events_collector.inc({'kind': 'timer_expiry'})
        loop.call_later(1.0, on_timer_expiry, loop, events_collector)

    loop = asyncio.get_event_loop()

    svr = Service(loop=loop)

    events_collector = Counter(
        "events",
        "Number of events.",
        const_labels={'host': socket.gethostname()})

    svr.registry.register(events_collector)

    loop.run_until_complete(svr.start())
    print('Serving prometheus metrics on: {}'.format(svr.metrics_url))

    loop.call_later(1.0, on_timer_expiry, loop, events_collector)

    try:
        loop.run_forever()
    except KeyboardInterrupt:
        pass
    finally:
        loop.run_until_complete(svr.stop())
    loop.close()

The example above shows a single Counter metric collector being created and exposed via a HTTP endpoint.

The counter metric is created to track the number of iterations. This example uses a timer callback to periodically increment the metric tracking iterations. In a realistic application a metric might track the number of requests, etc.

Following typical asyncio usage, an event loop is instantiated first then a metrics service is instantiated. The metrics service is responsible for managing the various metrics collectors and responding to Prometheus server when it requests metrics.

The server accepts various arguments such as the interface and port to bind to. The service will create a new collector registry if one is not passed in. A collector registry holds the various metrics collectors that will be exposed by the service.

The example script can be run using:

(env) $ cd examples
(env) $ python simple-example.py
Serving prometheus metrics on: http://0.0.0.0:50624/metrics

In another terminal fetch the metrics using the curl command line tool to verify they can be retrieved by Prometheus server.

By default metrics will be returned in plan text format.

$ curl http://0.0.0.0:50624/metrics
# HELP events Number of events.
# TYPE events counter
events{host="alpha",kind="timer_expiry"} 33
$ curl http://0.0.0.0:50624/metrics -H 'Accept: text/plain; version=0.0.4'
# HELP events Number of events.
# TYPE events counter
events{host="alpha",kind="timer_expiry"} 36

Similarly, you can request metrics in binary format, though this will be hard to read on the command line.

$ curl http://0.0.0.0:50624/metrics -H "ACCEPT: application/vnd.google.protobuf; proto=io.prometheus.client.MetricFamily; encoding=delimited"

There are more examples in the examples directory. The app-example.py file will likely be of interest as it provides a more representative application example.

A number of convenience decorator functions are also available to assist with updating metrics.

License

aioprometheus is released under the MIT license.

aioprometheus originates from the (now deprecated) prometheus python package which was released under the MIT license. aioprometheus continues to use the MIT license and contains a copy of the orignal MIT license from the prometheus-python project as instructed by the original license.