OpenTelemetry-Go: Exporter config logging may leak endpoint URLs in info logs

Summary

OpenTelemetry Go versions 1.5.0 through 1.44.0 can include trace exporter endpoint configuration in an internal diagnostic log emitted when an SDK TracerProvider is created. The default OpenTelemetry logger does not emit this event. Exposure requires an application to install a logger that enables OpenTelemetry's internal Info-level diagnostics and for someone other than the intended audience to have access to those logs.

The logged configuration can disclose the address of the trace collector and whether the OTLP/HTTP connection is configured as insecure. The Zipkin exporter logs its complete collector URL, so credentials in URL userinfo or tokens in the query string are also disclosed if an application embeds them there. OTLP authentication headers, TLS key material, and exported span data are not included in this log.

Exporter MarshalLog implementations that caused this configuration to be included in internal logs were introduced by a1fff3c.

Details

When sdk/trace.NewTracerProvider constructs a provider, it records a TracerProvider created internal Info event containing the provider configuration. In affected versions, the configuration's MarshalLog methods recursively include:

1. the provider's span processors;
2. each processor's span exporter; and
3. for the OTLP trace exporter, its client configuration.

This causes the following values to be present in the event:

• OTLP trace gRPC: the configured endpoint;
• OTLP trace HTTP: the configured endpoint and the Insecure flag; and
• Zipkin: the complete collector URL.

OpenTelemetry Go does not emit this event with its default logger, which only emits errors. An application must explicitly configure a sufficiently verbose logger with otel.SetLogger. The required logr verbosity is version-dependent:

• versions 1.5.0 through 1.14.x use V(1) for this Info event; and
• versions 1.15.0 through 1.44.0 use V(4).

OTLP header configuration is not part of the marshaled object, so credentials supplied with WithHeaders or the corresponding environment variables are not exposed. The documented OTLP WithEndpoint input is a collector address rather than a credential-bearing URL. The higher-risk case is therefore the Zipkin collector URL, which is retained and logged in full, or an application passing sensitive data in an OTLP endpoint outside the documented format.