Custom exporter using prometheus_python client

[basi...@gmail.com]

I was trying to write an exporter by following online instructions. While debugging an issue, noticed that 'collect' is executing twice for the below code. I am unable to figure out why. 

1. When I start the collector, it logs once. 

2018-02-20 05:26:39,670 - vnf_metrics.py - DEBUG - Starting script

2018-02-20 05:26:39,674 - vnf_metrics.py - DEBUG - inside collect

2018-02-20 05:26:39,674 - vnf_metrics.py - INFO - Metric samples count: 1

2. When I query 9503 port, I can see its executing twice. Is it the expected behavior or am I doing something wrong here?.

2018-02-20 05:27:33,735 - vnf_metrics.py - DEBUG - inside collect

2018-02-20 05:27:33,735 - vnf_metrics.py - INFO - Metric samples count: 1

2018-02-20 05:27:34,152 - vnf_metrics.py - DEBUG - inside collect

2018-02-20 05:27:34,152 - vnf_metrics.py - INFO - Metric samples count: 1

Code snippet:

---------------------

#!/usr/bin/env python

import os 

import sys

import time

sys.path.append('/opt/vnf_metrics/lib')

import logger

import prometheus_client

from prometheus_client import start_http_server, Metric, REGISTRY

class DataPublisher(object):

  def __init__(self):

      pass

  def collect(self):

      log.debug("inside collect")

      labels = {}

      metric = Metric('test_metrics1', 'Test metrics 1', 'counter')

      metric.add_sample('test_metrics1', value=float(1.00), labels=labels)

      log.info("Metric samples count: %d" % (len(metric.samples)))

      yield metric

def main():

  '''Main'''

  global log

  exclude_metrics = None

  log_dir = "/var/log"

  debug = True

  script_name = os.path.basename(sys.argv[0])

  log_file = os.path.join(log_dir,script_name + ".log")

  log = logger.setup_logger(script_name, log_file, debug)

  log.debug("Starting script")

  start_http_server(9503)

  REGISTRY.register(DataPublisher())

  while True: time.sleep(1)

if __name__ == '__main__':

  main()

[Brian Brazil]

On 20 February 2018 at 05:38, <basi...@gmail.com> wrote:

I was trying to write an exporter by following online instructions. While debugging an issue, noticed that 'collect' is executing twice for the below code. I am unable to figure out why. 

1. When I start the collector, it logs once. 

2018-02-20 05:26:39,670 - vnf_metrics.py - DEBUG - Starting script

2018-02-20 05:26:39,674 - vnf_metrics.py - DEBUG - inside collect

2018-02-20 05:26:39,674 - vnf_metrics.py - INFO - Metric samples count: 1

2. When I query 9503 port, I can see its executing twice. Is it the expected behavior or am I doing something wrong here?.

This is the expected behaviour, this is the auto-describe behaviour.  See the end of https://github.com/prometheus/client_python#custom-collectors

Brian

 

2018-02-20 05:27:33,735 - vnf_metrics.py - DEBUG - inside collect

2018-02-20 05:27:33,735 - vnf_metrics.py - INFO - Metric samples count: 1

2018-02-20 05:27:34,152 - vnf_metrics.py - DEBUG - inside collect

2018-02-20 05:27:34,152 - vnf_metrics.py - INFO - Metric samples count: 1

Code snippet:

---------------------

#!/usr/bin/env python

import 

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Brian Brazil

www.robustperception.io

[Michael]

I was wondering about the same issue and what I found was that when I was using chrome to scrape the exporter it was sending multiple get requests. Try hitting the exporter with curl and I think you'll see the collect method only executed once when you do a scrape.