Per-Instrumentation Configuration via Environment Variables

Is your feature request related to a problem? Please describe.

Yes. Currently, users cannot configure instrumentation-specific options (like GraphQLInstrumentation.mergeItems, PinoInstrumentation.disableLogSending, etc.) without using global.configureInstrumentations(), which requires code changes and defeats the "zero-code" promise.

The problem: When you define global.configureInstrumentations(), it completely replaces the default instrumentation system. You must manually import and configure ALL instrumentations you want, and OTEL_NODE_ENABLED_INSTRUMENTATIONS is ignored.

Example: To configure GraphQL with mergeItems: true while keeping http, grpc, pg, pino enabled, you must manually import and configure all 5 instrumentations in code, even though you only want to customize GraphQL.

// Must be at the top of handler file, before any imports
global.configureInstrumentations = async () => {
  // Must import ALL instrumentations manually
  const { GraphQLInstrumentation } = await import(
    "@opentelemetry/instrumentation-graphql"
  );
  const { HttpInstrumentation } = await import(
    "@opentelemetry/instrumentation-http"
  );
  const { GrpcInstrumentation } = await import(
    "@opentelemetry/instrumentation-grpc"
  );
  const { PgInstrumentation } = await import(
    "@opentelemetry/instrumentation-pg"
  );
  const { PinoInstrumentation } = await import(
    "@opentelemetry/instrumentation-pino"
  );

  return [
    new GraphQLInstrumentation({ mergeItems: true }), // Only GraphQL needs custom config
    new HttpInstrumentation(), // But must still include all others
    new GrpcInstrumentation(),
    new PgInstrumentation(),
    new PinoInstrumentation(),
  ];
};

Describe the solution you'd like

Add support for OTEL_INSTRUMENTATION_CONFIGS environment variable that accepts a JSON object mapping instrumentation names to their configurations. This works alongside OTEL_NODE_ENABLED_INSTRUMENTATIONS:

# Environment variables only - no code changes needed!
OTEL_NODE_ENABLED_INSTRUMENTATIONS="graphql,http,grpc,pg,pino"
OTEL_INSTRUMENTATION_CONFIGS={"graphql":{"mergeItems":true},"pino":{"disableLogSending":true}}

This would:

• Use OTEL_NODE_ENABLED_INSTRUMENTATIONS to determine which instrumentations to load (existing behavior)
• Apply configuration from OTEL_INSTRUMENTATION_CONFIGS to respective instrumentations
• Use defaults for instrumentations not specified in the config

Implementation: Add loadInstrumentationConfigs() function to parse the env var, and update defaultConfigureInstrumentations() in nodejs/packages/layer/src/wrapper.ts to merge user configs with defaults when creating instrumentations.

Describe alternatives you've considered

1. Per-instrumentation environment variables (e.g., OTEL_PINO_CONFIG) - Rejected: Would pollute env vars and doesn't scale with 30+ instrumentations
2. Keep current global.configureInstrumentations() approach - Rejected: Requires code changes, breaks zero-code promise
3. Configuration file - Rejected: Environment variables are more standard for Lambda and work better with AWS Systems Manager Parameter Store/Secrets Manager

Additional context

Benefits:

• True zero-code configuration via environment variables
• Works seamlessly with existing OTEL_NODE_ENABLED_INSTRUMENTATIONS
• Fully backwards compatible
• No code changes required in Lambda functions

Affected instrumentations: All 30+ instrumentations in the layer

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