Dry run using `validate` command is unable to detect Cycle in the pipeline

[sudiptob2]

Component(s)

connector/x

What happened?

Describe the bug

Dry run using validate command is unable to detect cycle in the pipeline.

Steps to reproduce

Invalid config

receivers:
  otlp:
    protocols:
      grpc:

exporters:
  debug:

connectors:
  forward:

service:
  pipelines:
    traces/in:
      receivers: [forward]
      processors: [ ]
      exporters: [forward]
    traces/out:
      receivers: [forward]
      processors: [ ]
      exporters: [forward]

This config.yaml passes validation

$ docker run -v $(pwd)/config.yaml:/etc/otelcol-contrib/config.yaml ghcr.io/open-telemetry/opentelemetry-collector-releases/opentelemetry-collector-contrib:0.120.0 validate --config=/etc/otelcol-contrib/config.yaml
$ echo $?
0

However upon using this configuration, collector fails to start.

$ docker run -v $(pwd)/config.yaml:/etc/otelcol-contrib/config.yaml ghcr.io/open-telemetry/opentelemetry-collector-releases/opentelemetry-collector-contrib:0.120.0 --config=/etc/otelcol-contrib/config.yaml

2025-03-03T17:05:07.121Z        info    service@v0.120.0/service.go:193 Setting up own telemetry...
Error: failed to build pipelines: cycle detected: connector "forward" (traces to traces) -> connector "forward" (traces to traces)
2025/03/03 17:05:07 collector server run finished with error: failed to build pipelines: cycle detected: connector "forward" (traces to traces) -> connector "forward" (traces to traces)

$ echo $?
1

What did you expect to see?

I expect the validator to return an error.

What did you see instead?

Validation passed with no error.

Collector version

0.120.0

Environment information

OpenTelemetry Collector configuration

receivers:
  otlp:
    protocols:
      grpc:

exporters:
  debug:

connectors:
  forward:

service:
  pipelines:
    traces/in:
      receivers: [forward]
      processors: [ ]
      exporters: [forward]
    traces/out:
      receivers: [forward]
      processors: [ ]
      exporters: [forward]

Log output

2025-03-03T17:05:07.121Z        info    service@v0.120.0/service.go:193 Setting up own telemetry...
Error: failed to build pipelines: cycle detected: connector "forward" (traces to traces) -> connector "forward" (traces to traces)
2025/03/03 17:05:07 collector server run finished with error: failed to build pipelines: cycle detected: connector "forward" (traces to traces) -> connector "forward" (traces to traces)

Additional context

No response

[github-actions]

Pinging code owners:

• connector/x: @mx-psi @dmathieu

See Adding Labels via Comments if you do not have permissions to add labels yourself.

[sudiptob2]

fixed by #12712