I’m trying to use the Opentelemetry Collector attributeprocessor to write a “hostname” attribute from the journald receiver _HOSTNAME attribute so that the json output will have a field “hostname” in it containing the name/value pair for the hostname.

Other than it not working, the challenge is also getting debug information, enabling debug logging doesn’t show me the processing of my rules. There is no error, if a rule doesn’t match it’s skipped.

The fields I’m trying to process are nested under a body element so what I’ve been trying to do is to change the “from_attribute” to all the possible values I think could be valid body__hostname, body._HOSTNAME, _HOSTNAME for example don’t work.

This is the collector configuration:

receivers:
  journald:

processors:
  resource:
    attributes:
    - action: insert
      key: loki.format
      value: json
    - action: insert
      key: environment
      value: dev
    - action: insert
      key: loki.resource.labels
      value: hostname, priority
  attributes:
    actions:
      - action: insert
        key: hostname
        from_attribute: _HOSTNAME
      - action: insert
        key: priority
        from_attribute: _PRIORITY

exporters:
  loki:
    endpoint: xxxx
    sending_queue:
      num_consumers: 10
      queue_size: 50000
    headers:
      "X-Scope-OrgID": "xxxx"
    tls:
      ca_file: xxxx
      cert_file: xxxx
      key_file: xxxx

service:
  pipelines:
    logs:
      receivers: [journald]
      processors: [attributes,resource]
      exporters: [loki]

And here is my message in Grafana showing the _HOSTNAME field nested under the body element along with all the other fields: