Missing custom labels from Alloy in Loki

Grafana Alloy
,
1

I have a Loki listening for logs.

Here is an excerpt from the nginx config:

	log_format main escape=json '{'
      .............
	'}';

	access_log /var/log/nginx/access.log main;

I parse the logs and add labels using Alloy.
I don’t have errors from Alloy.

local.file_match "applogs" {
  path_targets = [
    {
      __address__ = "localhost",
      __path__ = "/var/log/nginx/access.log",
      job = "nginx",
      instance = "localhost",
    },
  ]
}

loki.source.file "local_files" {
  targets = local.file_match.applogs.targets
  tail_from_end = true

  forward_to = [
	loki.process.add_new_label.receiver,
  ]
}

loki.process "add_new_label" {
	stage.labels {
		values = {
			test = "test",
		}
	}
	stage.structured_metadata {
		values={
			test1="test1",
		}
	}

  forward_to = [
    loki.write.grafana_loki.receiver,
  ]
}


loki.write "grafana_loki" {
  endpoint {
    url = "http://loki:3100/loki/api/v1/push"
  }
}

Checking labels via the API also doesn’t lead to anything.

root@yqhkujvybp:/# curl -s ‘``http://localhost:3100/loki/api/v1/labels``’
{“status”:“success”,“data”:[“filename”,“instance”,“job”,“service_name”]}

I would be grateful for any help!

2

The scope is too wide, it’s hard to tell what exactly the issue is. I would recommend first to make sure your logs are actually landing in Loki. Maybe try to remove all customized parsing blocks first.

3

The logs are displayed in grafana.

4

One thing to note, stage.labels is a reference, for example in your config:

stage.labels {
		values = {
			test = "test",
		}
	}

"test" needs to be a reference to another field that’s either pre-existing or a processed field from a previous step. If you just want to test, use static_labels instead. See loki.process | Grafana Alloy documentation