How to add the level tag in Promtail config

Question

I’m using grafana loki to compose dashboards. I need to group the logs by level to create the graph but in the details of the logs I can not see the level label:

my logs are like this:

2021-05-31 14:23:00.005  INFO 1 --- [   scheduling-1] AssociationService       : Scheduler Association finish at 31-05-2021 02:23:00

There is a way to extrapolate the level and associate it to the label "level"?

Answer 1

you might want to use the regex stage:

- job_name: my-job
  pipeline_stages:
  - regex: 
      # extracts only log_level from the log line
      expression: '\s+(?P<log_level>\D+)\s.*'
  - labels:
      # sources extracted log_level as label 'level' value
      level: log_level

the expression above matches only log_level, but you may add more named capture groups and use them in the same way
i.e.

^(?P<time>\d{4}-\d{2}-\d{2}\s\d{2}:\d{2}:\d{2}\.\d{3})\s+(?P<log_level>\S+)\s(?P<rest>.*)$

or less strict:

(?P<time>\S+\s\S+)\s+(?P<log_level>\D+)\s(?P<rest>.*)

match time, log_level and the rest of the line an extract them for later use.

check regex101 playground