service: configuration example for telemetry causes startup issue

[codeboten]

Component(s)

service

What happened?

the basic config for emitting internal metrics through OTLP from the docs, which worked in 0.121.0, crashes the 0.122.0 Collector
with the message:

2025/03/18 19:10:19 collector server run finished with error: failed to create SDK: must not specify multiple metric reader type

Collector version

v0.122.0

Environment information

No response

OpenTelemetry Collector configuration

receivers:
  nop:
exporters:
  nop:
service:
  pipelines:
    logs:
      receivers: [nop]
      processors: []
      exporters: [nop]
  telemetry:
    metrics:
      readers:
        - periodic:
            exporter:
              otlp:
                protocol: http/protobuf
                endpoint: https://backend:4318

Log output

Additional context

No response

[TylerHelmuth]

I am investigating

[TylerHelmuth]

I can see the issue is happening because the single Reader is getting configured with both the pull and periodic reader and the SDK rejects this. IDK yet why this is happening now.

[codeboten]

Further investigation by @TylerHelmuth, @evan-bradley and @dehaansa indicate this is related to b8830dd

[codeboten]

a potential workaround, it seems configuring a pull reader as well as a periodic reader allows the collector to start:

service:
  telemetry:
    metrics:
      readers:
        - pull:
            exporter:
              prometheus:
                host: localhost
                port: 8889
        - periodic:
            exporter:
              otlp:
                protocol: http/protobuf
                endpoint: https://backend:4318

[jade-guiton-dd]

Since the 0.122.1 tag has been released, should this be considered resolved?

[TylerHelmuth]

Once open-telemetry/opentelemetry-collector-releases#882 is merged and tagged

[mx-psi]

Once open-telemetry/opentelemetry-collector-releases#882 is merged and tagged

Closing since this is done