Logger 'OtlpLogExporter' ignores standard settings if not coming from actual Environment Variables

[julealgon]

Bug Report

List of all OpenTelemetry NuGet
packages and version that you are
using (e.g. OpenTelemetry 1.0.2):

• OpenTelemetry.Exporter.OpenTelemetryProtocol.Logs v1.4.0-rc.4

Runtime version (e.g. net462, net48, netcoreapp3.1, net6.0 etc. You can
find this information from the *.csproj file):

• net48/net6.0/net7.0

Symptom

When providing the OTEL_EXPORTER_OTLP_ENDPOINT value through a source other than environment variables, the setting is completely ignored for the logging configuration, but is honored for the tracing and metrics ones.

What is the expected behavior?

I'd expect for all the standard configuration keys to be honored in all 3 telemetry flows in the same way so that I can centralize and simplify my configuration.

What is the actual behavior?

Logs are not pushed to my collector address, since it keeps targeting the standard localhost endpoint.

Reproduce

https://github.com/julealgon/OTELLoggingIgnoresConfigurationSample

Sample contains 2 launch profiles:

• AppSettings: passes OTEL_EXPORTER_OTLP_ENDPOINT via appsettings.json
• EnvVars: passes OTEL_EXPORTER_OTLP_ENDPOINT via an environment variable

It produces a small log when run.

For the AppSettings scenario:

 info: OTELLoggingIgnoresConfigurationSample.Worker[0]
      Worker running at: 03/03/2023 10:34:19 -03:00.
          'OTEL_EXPORTER_OTLP_ENDPOINT' from env var: (null)
          'OTEL_EXPORTER_OTLP_ENDPOINT' from configuration: http://192.168.0.0:4317
          Otpl endpoint from OtlpExporterOptions: http://localhost:4317/

For the EnvVars scenario:

info: OTELLoggingIgnoresConfigurationSample.Worker[0]
      Worker running at: 03/03/2023 10:35:07 -03:00.
          'OTEL_EXPORTER_OTLP_ENDPOINT' from env var: http://192.168.0.0:4317
          'OTEL_EXPORTER_OTLP_ENDPOINT' from configuration: http://192.168.0.0:4317
          Otpl endpoint from OtlpExporterOptions: http://192.168.0.0:4317/

Additional Context

This happens because of the way the options instance is initialized inside the AddOtlpExporter extension:

opentelemetry-dotnet/src/OpenTelemetry.Exporter.OpenTelemetryProtocol.Logs/OtlpLogExporterHelperExtensions.cs

Line 58 in 690f7e5

var exporterOptions = new OtlpExporterOptions();

opentelemetry-dotnet/src/OpenTelemetry.Exporter.OpenTelemetryProtocol/OtlpExporterOptions.cs

Lines 60 to 61 in 690f7e5

	public OtlpExporterOptions()
	: this(new ConfigurationBuilder().AddEnvironmentVariables().Build(), new())

This is related to:

• Improve DI friendliness of Logging #4014

[noahfalk]

+1 I just hit this issue. I had the configuration inside appsettings.json and was very puzzled why metrics were being reported but logs were not.