'Incorrect label' error when extracting value AND additional attribute from __value__

[code77]

Hello,

I came across this project and it's great. It's exactly what I need for my project in which I'm receiving json messages over MQTT.

The problem I'm facing, is that I cannot extract any additional attributes on top of the numeric value.
For simplicity of the example let's imagine my MQTT data looks like this

someAttribute=A;val=123

(in reality it's json but this regex will be simpler)

This works:

metrics:
  - name:     'example' 
    help:     'help text' 
    type:     'counter'
    topic:    'topics/+'
    label_configs:
      - source_labels:  ['__value__'] 
        regex:          '.*val=(.*)'
        target_label:   '__value__'
        replacement:    '\1'
        action:         'replace'

This doesn't work:

metrics:
  - name:     'example' 
    help:     'help text' 
    type:     'counter'
    topic:    'topics/+'
    label_configs:
      - source_labels:  ['__value__'] 
        regex:          '.*someAttribute=(.*);.*'
        target_label:   'attributeLabel'
        replacement:    '\1'
        action:         'replace'
      - source_labels:  ['__value__'] 
        regex:          '.*val=(.*)'
        target_label:   '__value__'
        replacement:    '\1'
        action:         'replace'

and I get

  File "C:\k\temp\git_projects\mqtt_exporter\mqtt_exporter.py", line 384, in _export_to_prometheus
    prometheus_metric.update(label_values, value)
  File "C:\k\temp\git_projects\mqtt_exporter\mqtt_exporter.py", line 450, in update
    child = self.metric.labels(*label_values)
  File "C:\Users\toadc\AppData\Local\Programs\Python\Python310\lib\site-packages\prometheus_client\metrics.py", line 164, in labels
    raise ValueError('Incorrect label count')

even though, I can see in the debug logs that the conversion was successful

[fhemberger]

Hi, thanks for pointing this out. I'll try to look into it …