Prometheus counter not yielding in custom collector

Question

I am writing this custome collector where I want to add a counter.

#!/usr/bin/env python3
import sys
import time

from prometheus_client import start_http_server
from prometheus_client.core import CollectorRegistry, Counter

class MyCollector():
    def __init__(self):
        self.mymetrics_counter = Counter('observability_total', 'Status of My Services', ['app', 'test'])
        
    def describe(self):
        print("Started: Metrics Collector!")
        return list()
    
    def collect(self):
        self.mymetrics_counter.labels('observability', 'test').inc()
        yield self.mymetrics_counter

if __name__ == '__main__':
    try:
        myregistry = CollectorRegistry()
        myregistry.register(MyCollector())
        start_http_server(port=9100, registry=myregistry)
        while True:
            time.sleep(10)
    except KeyboardInterrupt:
        print("Ended: Metrics Collector!")
        sys.exit(0)

But I am getting below error upon yeild

(venv) test_collector % python mycollector.py
Started: Metrics Collector!
Traceback (most recent call last):
  File "/Library/Frameworks/Python.framework/Versions/3.9/lib/python3.9/wsgiref/handlers.py", line 137, in run
    self.result = application(self.environ, self.start_response)
  File "/Users/myid/Documents/myproj/workspace/test_collector/venv/lib/python3.9/site-packages/prometheus_client/exposition.py", line 123, in prometheus_app
    status, header, output = _bake_output(registry, accept_header, params)
  File "/Users/myid/Documents/myproj/workspace/test_collector/venv/lib/python3.9/site-packages/prometheus_client/exposition.py", line 105, in _bake_output
    output = encoder(registry)
  File "/Users/myid/Documents/myproj/workspace/test_collector/venv/lib/python3.9/site-packages/prometheus_client/exposition.py", line 179, in generate_latest
    mname = metric.name
AttributeError: ("'Counter' object has no attribute 'name'", prometheus_client.metrics.Counter(observability))

score 0 · Answer 1 · answered Jun 12 '21 at 09:43

0

collect returns metric families, not metrics. If you yield each of the results of mymetrics_counter.collect() it'd work.

Also, when you create the Counter its getting registered to the default registry which you don't want in this soft of usage as it'll end up returned twice which is invalid.

answered Jun 12 '21 at 09:43

brian-brazil

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Thanks @brian-brazil, I tried `yield self.mymetrics_counter.collect()` and changed the registry to default but then I get below error -> `AttributeError: ("'list' object has no attribute 'name'", [Metric(observability, Status of My Services, counter, , [Sample(name='observability_total', labels={'app': 'observability', 'test': 'test'}, value=1.0, timestamp=None, exemplar=None), Sample(name='observability_created', labels={'app': 'observability', 'test': 'test'}, value=1623696998.4481, timestamp=None, exemplar=None)` – dganesh2002 Jun 14 '21 at 19:01

Prometheus counter not yielding in custom collector

1 Answers1