concat can't make up its mind

[yshollander-selerity]

Component(s)

processor/transform

What happened?

Description

I am setting up opentelemetry-contrib to send JMX statistics collected from a running Java process to an existing Graphite installation. I can't concatenate a prefix to the metric before I send it out via the carbon exporter.

Steps to Reproduce

Run opentelemetry contrib collector with the above configuration.

# otelcol-contrib --version otelcol-contrib version 0.127.0

Expected Result

Properly transformed metrics sent to Graphite.

Actual Result

OpenTelemetry fails with an error message. I've tried several variations of the concat, with no luck. Example log messages below.

Collector version

otelcol-contrib version 0.127.0

Environment information

Environment

OS: Ubuntu 18.04
Compiler(if manually compiled): n/a, used otelcol-contrib_0.127.0_linux_amd64.deb

OpenTelemetry Collector configuration

receivers:
  jmx:
    jar_path: /opt/opentelemetry/jmx/opentelemetry-jmx-metrics.jar
    endpoint: localhost:2126
    target_system: jvm

processors:
  resource/add_carbon_prefix:
    attributes:
      - key: carbon.metric.root_prefix 
        value: "hosts.myhostname.jmx." 
        action: insert
  transform/carbon_prefix:
    metric_statements:
      - context: metric
        statements:
          - set(name, Concat([resource.attributes["carbon.metric.root_prefix"], name]))

  batch: {}

exporters:
  carbon:
    endpoint: "graphite.mycompany.com:2003"


service:
  pipelines:
    metrics/jmx:
      receivers: [jmx]
      processors: [transform/carbon_prefix,batch]
      exporters: [carbon]
  telemetry:
    logs:
      level: debug

Log output

Two examples:

Error: invalid configuration: processors::transform/carbon_prefix: unable to parse OTTL statement "set(metric.name, Concat([resource.attributes[\"carbon.metric.root_prefix\"], metric.name]))": error while parsing arguments for call to "set": invalid argument at position 1: error while parsing arguments for call to "Concat": incorrect number of arguments. Expected: 2 Received: 1

Error: invalid configuration: processors::transform/carbon_prefix: unable to parse OTTL statement "set(metric.name, Concat(resource.attributes[\"carbon.metric.root_prefix\"], metric.name))": error while parsing arguments for call to "set": invalid argument at position 1: error while parsing arguments for call to "Concat": invalid argument at position 0: must be a list of type StringLikeGetter[github.com/open-telemetry/opentelemetry-collector-contrib/pkg/ottl/contexts/ottlmetric.TransformContext]

Additional context

No response

[github-actions]

Pinging code owners:

• processor/transform: @TylerHelmuth @evan-bradley @edmocosta

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[VihasMakwana]

@yshollander-selerity Hello!

Please refer the Concat documentation for correct format. Concat expects a 2nd argument, delimiter, which is placed between strings during concatenation.

In your case, correct function should be:

Concat([resource.attributes["carbon.metric.root_prefix"], name], ..your delimiter..)