问如何使用prom尾scrape_configs提取日志级别

EN

[2021-12-14 11:11:11] INFO forcetask[id=pod-0] message2
[2021-12-14 11:11:11] INFO forcetask[id=pod-0] message1

{log="[2021-12-14 11:11:11] INFO forcetask[id=pod-0] message2", stream="stdout", timestamp ="..."}
{log="[2021-12-14 11:11:11] ERROR forcetask[id=pod-0] Error1", stream="stderr", timestamp="..."}

scrape_configs:
- job_name: my-custom-labels
  pipeline_stages:
  - docke: {}
  - json:
      log: log
      stream: stream
      timestamp: timestamp
  - labels: 
       log:
  - match:
      selector: '{app="loki"}'.    -- this is one of the labels of Loki instance 
      stages:
      - regex: 
          expression: '\\[(?P<timestamp>\\d{4}-\\d{2}-\\d{2}\\s\\d{2}:\\d{2}:\\d{2})\\]\\s(?P<level>\\w+)\\s(?P<message>.*)'
      - labels:
          level:
      - timestamp:
          format: RFC3339Nano
          source: timestamp