Indexed labels in Loki with OTLP

Grafana Loki
,
1

I send logs using Alloy 1.8.2 to Loki (tested with 3.4.2 and 3.5.0) with OTLP endpoint. This works fine.
The configuration of the indexed labels in Loki is changed to allow only a few labels to be indexed. But this does not work. The service.name in Loki becomes unknown_service and all other fields are structured_metadata and not indexed fields. I’ve been searching and testing a whiole day and tried several configurations I found but I cannot gwet it working.
What I am doing wrong?

I sent some sample requests using curl to Loki. It seems that attributes in resource section become indexed labels and attributes in logRecords section not. Can I change this with Alloy?

Loki config

  limits_config:
    allow_structured_metadata: true
    otlp_config:
      resource_attributes:
        # ignore_defaults: true
        attributes_config:
          - action: index_label
            attributes:
              - customer
              - hostname
              - host.name
              - job
              - service.name
              - stage
  distributor:
    otlp_config:
      default_resource_attributes_as_index_labels: []

Sample log from Alloy live debug

LogRecord #0
ObservedTimestamp: 2025-05-08 08:40:12.009693043 +0000 UTC
Timestamp: 2025-05-08 08:40:11.548241 +0000 UTC
SeverityText: 
SeverityNumber: Unspecified(0)
Body: Str(Removed slice User Slice of UID 0.)
Attributes:
     -> service_name: Str(integrations/journald)
     -> host.name: Str(test)
     -> job: Str(integrations/journald)
     -> systemd_unit: Str(init.scope)
     -> service.name: Str(integrations/journald)
     -> stage: Str(test)
     -> customer: Str(demo)
Trace ID:

Sample log in Grafana

image
image1224×548 51.9 KB

2

Found the solution here, now it works