Coldstart Processor creating broken traces for cold start and next invocation

[jousby]

Describe the bug
I was unable to get the coldstart processor to do what is says that it does on the tin. If i submit 4 requests to a helloworld function behind an api gateway I only end up with 3 traces in my observability platform. Two of these traces will use the same internal spans, have missing spans and appears to be related to the cold start. One trace goes missing. Invocations from coldstart + 3 appear normal.

Steps to reproduce

• Create a hello world Lambda function fronted by either a REST or HTTP api in AWS
• Deploy the api and function with the otel collector and nodejs layers bundled with a custom collector.yaml that enables the coldstart processor. ie.

processors:
  coldstart:
  resource:
    attributes:
      - key: deployment.environment.name
        value: '${env:ENVIRONMENT_NAME}'
        action: upsert

Additional configure the collector.yaml to send to your observability platform of choice.
I had the following env variables set for the function:

      // OpenTelemetry configuration
      AWS_LAMBDA_EXEC_WRAPPER: '/opt/otel-handler',
      OPENTELEMETRY_COLLECTOR_CONFIG_URI: '/var/task/collector.yaml',
      OTEL_TRACES_SAMPLER: 'always_on',
      OTEL_PROPAGATORS: 'tracecontext,baggage',
      OTEL_LAMBDA_DISABLE_AWS_CONTEXT_PROPAGATION: 'true',
      OTEL_NODE_ENABLED_INSTRUMENTATIONS: 'aws-sdk,aws-lambda,http,undici',
      OTEL_SERVICE_NAME: serviceName,
      OPENTELEMETRY_EXTENSION_LOG_LEVEL: 'INFO',

I tried active tracing on, passthrough and off.
I tried the insights layer on and off.

• Manually trigger a http get request to the api/function endpoint four times
• Check traces that arrive in the observability platform

What did you expect to see?
I expected to see 4 traces arrive in my observability platform (grafana cloud). I expected the first trace that would have triggered a cold start to have a trace that includes a span for the init phase and be of a longer duration than the other three.

What did you see instead?

• Only three traces arrived.

• One trace went missing

• The first two traces are broken

  • trace 1
  
  • trace 2
  
  • trace 3
  

What version of collector/language SDK version did you use?

• 0.19.0 (collector layer)
• 0.19.0 (nodejs layer)

What language layer did you use?
nodejs

Additional context
I tried a few different things to try and get this to work:

• bundling to commonjs and esm
• using a http or rest api gateway
• removing the batch and decouple processors
• putting the coldstart processor first/last in order of execution
• setting the function active tracing to on, passthrough and off.
• removing the insight lambda layer

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