Add pipeline ID to the error message for unused connectors.

[sudiptob2]

Description

As mentioned in this #8721 (comment), the error message for unused connectors currently lacks specific pipeline names, making debugging more difficult.

This PR enhances the error message by including pipeline names in the [signal/name] format, consistent with how they appear in config.yaml. This provides a better context for identifying misconfigurations.

Link to tracking issue

Related to #8721

Testing

A few scenarios and example output are given below. I will do additional testing and add unit tests if necessary.

1. Used as a receiver but not used as an exporter with 1 signal

config.yaml

receivers:
  otlp:
    protocols:
      grpc:
exporters:
  debug:
connectors:
  forward:
service:
  pipelines:
    logs/in:
      receivers: [otlp]
      processors: []
      exporters: [debug]
    logs/out:
      receivers: [forward]
      processors: []
      exporters: [debug]

Main Branch Output:

Error: failed to build pipelines: connector "forward" used as receiver in logs pipeline but not used in any supported exporter pipeline

Proposed Output:

Error: failed to build pipelines: connector "forward" used as receiver in [logs/out] pipeline but not used in any supported exporter pipeline

2. Plain

config.yaml

receivers:
  otlp:
    protocols:
      grpc:
exporters:
  debug:
connectors:
  forward:
service:
  pipelines:
    traces:
      receivers: [ otlp ]
      processors: [ ]
      exporters: [ forward ]
    metrics:
      receivers: [ forward ]
      processors: [ ]
      exporters: [ debug ]

Main Branch Output:

Error: failed to build pipelines: connector "forward" used as exporter in traces pipeline but not used in any supported receiver pipeline

Proposed Output:

Error: failed to build pipelines: connector "forward" used as exporter in [traces] pipeline but not used in any supported receiver pipeline

3. Multiple pipeline

config.yaml

receivers:
  otlp:
    protocols:
      grpc:
exporters:
  debug:
connectors:
  forward:
service:
  pipelines:
    logs/in:
      receivers: [otlp]
      processors: []
      exporters: [forward]
    logs/in2:
      receivers: [ otlp ]
      processors: [ ]
      exporters: [ forward ]
    logs/out:
      receivers: [otlp]
      processors: []
      exporters: [debug]
    traces:
      receivers: [ otlp ]
      processors: [ ]
      exporters: [ forward ]
    metrics:
      receivers: [ forward ]
      processors: [ ]
      exporters: [ debug ]

Main Branch Output:

Error: failed to build pipelines: connector "forward" used as exporter in logs pipeline but not used in any supported receiver pipeline

Proposed Output:

Error: failed to build pipelines: connector "forward" used as exporter in [logs/in2 logs/in] pipeline but not used in any supported receiver pipeline

[linux-foundation-easycla]

The committers listed above are authorized under a signed CLA.

• ✅ login: bogdandrutu / name: Bogdan Drutu (b9fe547, 8c3e534)
• ✅ login: sudiptob2 / name: Sudipto Baral (9faed07, 1d460d9, 2fd447d)

[sudiptob2]

Thank you so much for your quick response and amazing suggestions. I have made the adjustment, let me know how it looks @bogdandrutu

[jmacd]

Nice!

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 92.10%. Comparing base (4c4a9c2) to head (8c3e534).
Report is 1 commits behind head on main.

Additional details and impacted files

@@           Coverage Diff           @@
##             main   #12410   +/-   ##
=======================================
  Coverage   92.09%   92.10%           
=======================================
  Files         465      465           
  Lines       25173    25180    +7     
=======================================
+ Hits        23184    23191    +7     
  Misses       1592     1592           
  Partials      397      397           

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[sudiptob2]

@bogdandrutu Thanks for approving the PR earlier. I added a changelog entry. Could you please re-review?