stage.json of loki.process cannot have hyphen (-) in the expressions value

[pschiffe]

What's wrong?

This is actually a bug in the jmespath/go-jmespath - jmespath/go-jmespath#58
but I wanted to bring it to your attention as well, as it was hard to debug

Workaround for me is to define it like this:

    stage.json {
      expressions = {
        http_user_agent = "\"request_User-Agent\"",
      }
    }

Steps to reproduce

Try to load the provided config.

System information

6.5.10-200.fc38.aarch64

Software version

grafana-agent-flow-0.38.0-1.aarch64

Configuration

loki.process "enrich" {
  forward_to = [loki.write.default.receiver]

  stage.match {
    selector = "{container=\"traefik\"}"

    stage.json {
      expressions = {
        http_user_agent = "request_User-Agent",
      }
    }
  }
}

Logs

Error: /etc/grafana-agent-flow.river:308:1: Failed to build component: building component: invalid stage config invalid stage config could not compile JMES expression: SyntaxError: Unexpected token at the end of the expression: tNumber: match stage failed to create pipeline from config: {{container="traefik"} [{<nil> <nil> <nil> <nil> <nil> <nil> <nil> <nil> <nil> <nil> <nil> <nil> <nil> <nil> <nil> <nil> <nil> <nil> <nil> 0x4002ab7618 <nil> <nil> <nil> <nil> <nil>} {<nil> <nil> <nil> <nil> <nil> <nil> 0x4002bf4768 <nil> <nil> <nil> <nil> <nil> <nil> <nil> <nil> <nil> <nil> <nil> <nil> <nil> <nil> <nil> <nil> <nil> <nil>} {<nil> <nil> <nil> <nil> <nil> <nil> <nil> <nil> <nil> 0x4002ab7638 <nil> <nil> <nil> <nil> <nil> <nil> <nil> <nil> <nil> <nil> <nil> <nil> <nil> <nil> <nil>}] keep  }

[github-actions]

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[tpaschalis]

Thanks for the report and explanation @pschiffe, much appreciated!

Since the issue has a workaround and there doesn't seem to be any fix candidates upstream, I'm going to label this as a docs issue and add the necessary documentation for any future visitors.