Enhance config validation by Instantiating service during dryrun.

[sudiptob2]

Description

As mentioned in #8721 (comment), we can surface configuration errors by instantiating the service during a dry run.

Expanding on this idea, this PR enhances configuration validation. The validate command will now capture all validation errors that would prevent the collector from starting.

Link to the tracking issue

Fixes #8721

Testing

Added unit tests. Also, a few scenarios and example output are given below. I will add more unit tests if necessary.

1. Improper Connector Use

invalid_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 ]

Before: No error detected

Proposed Change:

Error: failed to build pipelines: connector "forward" used as exporter in [logs/in2 logs/in] pipeline but not used in any supported receiver pipeline
2025/02/25 16:58:09 collector server run finished with error: failed to build pipelines: connector "forward" used as exporter in [logs/in2 logs/in] pipeline but not used in any supported receiver pipeline

2. Unused Connector

invalid_config.yaml

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

Before: No error detected

Proposed Change:

Error: failed to build pipelines: connector "forward" used as receiver in [logs/out] pipeline but not used in any supported exporter pipeline
2025/02/26 10:40:53 collector server run finished with error: failed to build pipelines: connector "forward" used as receiver in [logs/out] pipeline but not used in any supported exporter pipeline

2. Cycle in the Pipeline

invalid_config.yaml

receivers:
  otlp:
    protocols:
      grpc:

exporters:
  debug:

connectors:
  forward:

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

Before: No error detected

Proposed Change:

Error: failed to build pipelines: cycle detected: connector "forward" (traces to traces) -> connector "forward" (traces to traces)
2025/02/26 11:12:53 collector server run finished with error: failed to build pipelines: cycle detected: connector "forward" (traces to traces) -> connector "forward" (traces to traces)

Note

I removed the following log as it seemed redundant to me and it is also surfaced during validation. Let me know if we absolutely need to keep it

opentelemetry-collector/service/service.go

Line 193 in 5812712

logger.Info("Setting up own telemetry...")

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 92.03%. Comparing base (0faea29) to head (bce7fac).

Additional details and impacted files

@@            Coverage Diff             @@
##             main   #12488      +/-   ##
==========================================
+ Coverage   92.00%   92.03%   +0.03%     
==========================================
  Files         469      469              
  Lines       25355    25358       +3     
==========================================
+ Hits        23327    23339      +12     
+ Misses       1619     1613       -6     
+ Partials      409      406       -3     

☔ View full report in Codecov by Sentry.
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[sudiptob2]

Some tests are failing, which are not related to this PR. Any guidance would be helpful.

[mx-psi]

What are the errors that were not reported before that are reported after this change? Can we instead statically validate those?

[mx-psi]

Feel free to ignore the errors, they are not related to this PR

[sudiptob2]

@mx-psi Thanks for the quick response!

What are the errors that were not reported before that are reported after this change? Can we instead statically validate those?

This approach should catch all errors in the pipeline configuration. I am not aware of it all, but here are a couple of examples.

Especially for $\textcolor{red}{\textsf{cycle detection,}}$ we need to initialize the graph. Statically verifying that might not be feasible.

1. Improper Connector Use

invalid_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 ]

Before: No error detected

Proposed Change:

Error: failed to build pipelines: connector "forward" used as exporter in [logs/in2 logs/in] pipeline but not used in any supported receiver pipeline
2025/02/25 16:58:09 collector server run finished with error: failed to build pipelines: connector "forward" used as exporter in [logs/in2 logs/in] pipeline but not used in any supported receiver pipeline

2. Unused Connector

invalid_config.yaml

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

Before: No error detected

Proposed Change:

Error: failed to build pipelines: connector "forward" used as receiver in [logs/out] pipeline but not used in any supported exporter pipeline
2025/02/26 10:40:53 collector server run finished with error: failed to build pipelines: connector "forward" used as receiver in [logs/out] pipeline but not used in any supported exporter pipeline

2. Cycle in the Pipeline

invalid_config.yaml

receivers:
  otlp:
    protocols:
      grpc:

exporters:
  debug:

connectors:
  forward:

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

Before: No error detected

Proposed Change:

Error: failed to build pipelines: cycle detected: connector "forward" (traces to traces) -> connector "forward" (traces to traces)
2025/02/26 11:12:53 collector server run finished with error: failed to build pipelines: cycle detected: connector "forward" (traces to traces) -> connector "forward" (traces to traces)

[bogdandrutu]

why this? Why do we need to start things to make sure we are ok?

[sudiptob2]

I think it does not start a service. As mentioned in this #8721 (comment) we can surface configuration errors by instantiating the service during a dry run. This will initialize the graph, and detect cycles and other errors which might prevent the service to start.

[bogdandrutu]

I would prefer the DryRun to not have to start the collector, what do we miss that we need to do this?

[sudiptob2]

I would prefer the DryRun to not have to start the collector, what do we miss that we need to do this?

These are the error that current validate command can not detect

1. Improper Connector Use

invalid_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 ]

Before: No error detected

Proposed Change:

Error: failed to build pipelines: connector "forward" used as exporter in [logs/in2 logs/in] pipeline but not used in any supported receiver pipeline
2025/02/25 16:58:09 collector server run finished with error: failed to build pipelines: connector "forward" used as exporter in [logs/in2 logs/in] pipeline but not used in any supported receiver pipeline

2. Unused Connector

invalid_config.yaml

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

Before: No error detected

Proposed Change:

Error: failed to build pipelines: connector "forward" used as receiver in [logs/out] pipeline but not used in any supported exporter pipeline
2025/02/26 10:40:53 collector server run finished with error: failed to build pipelines: connector "forward" used as receiver in [logs/out] pipeline but not used in any supported exporter pipeline

2. Cycle in the Pipeline

invalid_config.yaml

receivers:
  otlp:
    protocols:
      grpc:

exporters:
  debug:

connectors:
  forward:

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

Before: No error detected

Proposed Change:

Error: failed to build pipelines: cycle detected: connector "forward" (traces to traces) -> connector "forward" (traces to traces)
2025/02/26 11:12:53 collector server run finished with error: failed to build pipelines: cycle detected: connector "forward" (traces to traces) -> connector "forward" (traces to traces)