It sounds like you’re experiencing an issue where logs are successfully sent to New Relic during application startup but fail to appear when handling HTTP requests. This discrepancy typically points to differences in how logging is handled in these two phases, possibly related to log correlation with traces and spans.

Here are several steps and considerations to help you identify and resolve the issue:

1- Verify Log Correlation Attributes

Issue: During HTTP request handling, logs are often correlated with traces and spans. If these logs lack the necessary correlation attributes, New Relic might not display them as expected.

Solution:

• Check Trace and Span IDs: Ensure that the logs emitted during HTTP requests include the trace_id and span_id. You can verify this by inspecting the logs in the ConsoleExporter. They should contain these IDs when correlated with a trace.

// Example log with trace context
logger.LogInformation("Handling request {RequestPath}", context.Request.Path);

• Resource Configuration: Make sure that the Resource is correctly configured to include necessary attributes that New Relic expects for correlation.

.ConfigureResource(resourceBuilder => resourceBuilder
    .AddService(Otel.ServiceName, serviceVersion: Otel.ServiceVersion)
    // Add additional attributes if required by New Relic
)

2- Ensure Proper OpenTelemetry Pipeline Configuration

Issue: Misconfigurations in the OpenTelemetry logging pipeline can prevent logs from being exported correctly during HTTP requests.

Solution:

• Separate Pipelines:
  Although youre using a single AddOpenTelemetry setup, consider separating logging, tracing, and metrics pipelines to isolate and identify issues more effectively.

builder.Services.AddOpenTelemetryLogging(logging => {
    logging
        .AddConsoleExporter()
        .AddOtlpExporter(otlp => {
            otlp.Endpoint = new Uri($"{_otelEndpoint}/v1/logs");
            otlp.Headers = $"api-key={_otelApiKey}";
            otlp.Protocol = _otelProtocol;
        })
        .SetResourceBuilder(ResourceBuilder.CreateDefault().AddService(Otel.ServiceName));
});

builder.Services.AddOpenTelemetryTracing(tracing => {
    tracing
        .AddAspNetCoreInstrumentation()
        .AddHttpClientInstrumentation()
        // Add other instrumentation as needed
        .AddOtlpExporter(otlp => {
            otlp.Endpoint = new Uri($"{_otelEndpoint}/v1/traces");
            otlp.Headers = $"api-key={_otelApiKey}";
            otlp.Protocol = _otelProtocol;
        })
        .SetResourceBuilder(ResourceBuilder.CreateDefault().AddService(Otel.ServiceName));
});

builder.Services.AddOpenTelemetryMetrics(metrics => {
    metrics
        .AddAspNetCoreInstrumentation()
        .AddHttpClientInstrumentation()
        // Add other instrumentation as needed
        .AddOtlpExporter(otlp => {
            otlp.Endpoint = new Uri($"{_otelEndpoint}/v1/metrics");
            otlp.Headers = $"api-key={_otelApiKey}";
            otlp.Protocol = _otelProtocol;
        })
        .SetResourceBuilder(ResourceBuilder.CreateDefault().AddService(Otel.ServiceName));
});

• Flush the Exporters: Ensure that the exporters are properly flushed on application shutdown to prevent loss of logs.

var app = builder.Build();
app.Lifetime.ApplicationStopping.Register(() => {
    app.Services.GetRequiredService<TracerProvider>().Dispose();
    app.Services.GetRequiredService<LoggerProvider>().Dispose();
    app.Services.GetRequiredService<MeterProvider>().Dispose();
});

• Consult Documentation: Review New Relic’s OpenTelemetry Logs Documentation to ensure that your logs comply with their ingestion requirements.

• Required Attributes: Make sure that logs include attributes like service.name, trace_id, and span_id, which are crucial for correlation.

4 – Validate Exporter Configuration

Issue: Incorrect OTLP exporter settings can prevent logs from being sent correctly to New Relic.

Solution:

• Endpoint Verification: Double-check that the OTLP log endpoint (${_otelEndpoint}/v1/logs) is correct and accessible from your application environment.

• Headers and Authentication: Ensure that the api-key and any other required headers are correctly set. Incorrect headers can result in silent failures where logs are not ingested.

otlp.Headers = $"api-key={_otelApiKey}";

• Protocol Compatibility: Confirm that the protocol (Http/Protobuf) is supported and correctly configured on both the exporter and New Relic’s side.

5 – Increase Diagnostic Logging

Issue: Silent failures can make it challenging to identify why logs aren’t appearing in New Relic.

Solution:

- **Enable OpenTelemetry Diagnostics:** Enhance the verbosity of OpenTelemetry diagnostics to capture more detailed information about the logging pipeline.

// OTEL_DIAGNOSTICS.json
{
    "Logging": {
        "LogLevel": {
            "Default": "Debug",
            "OpenTelemetry": "Debug"
        }
    }
}

• Review Logs: After increasing verbosity, inspect the diagnostic logs to identify any issues or anomalies when handling HTTP requests.

6 – Test with OpenTelemetry Collector

Issue: To isolate whether the issue is with your application or New Relic, you can use an intermediary like the OpenTelemetry Collector.

Solution:

• Set Up Collector: Configure the OpenTelemetry Collector to receive logs from your application and then forward them to New Relic. This can help determine if logs are correctly exported from your application.

# Example Collector configuration
receivers:
  otlp:
    protocols:
      http:
      grpc:

exporters:
  newrelic:
    api_key: YOUR_NEW_RELIC_API_KEY
    endpoint: https://log-api.newrelic.com/log/v1

service:
  pipelines:
    logs:
      receivers: [otlp]
      exporters: [newrelic]

• Monitor Collector Logs: Check the Collector’s logs to ensure that logs are being received and forwarded without issues.

7 – Update OpenTelemetry and New Relic SDKs

Issue: Incompatibilities or bugs in older versions of SDKs can lead to unexpected behavior.

Solution:

• Upgrade Packages: Ensure that you are using the latest versions of OpenTelemetry and New Relic SDKs. Updates often include bug fixes and improvements.

dotnet add package OpenTelemetry
dotnet add package OpenTelemetry.Exporter.OpenTelemetryProtocol
dotnet add package NewRelic.OpenTelemetry


8 - Contact New Relic Support

Issue: If after all these steps the issue persists, it might be specific to your New Relic account or a deeper integration issue.

Solution:

 - **Provide Detailed Information:** Reach out to New Relic Support with detailed information about your setup, configuration files, and any diagnostic logs you've collected.
 - **Share Samples:** If possible, share sample logs that are not appearing in New Relic to help them diagnose the issue more effectively.

Summary

Your configuration appears mostly correct, but the issue likely revolves around how logs are correlated with traces during HTTP request handling. By verifying that logs include necessary correlation attributes, ensuring compatibility with New Relic’s requirements, and isolating the problem through diagnostic logging and possibly the OpenTelemetry Collector, you should be able to identify and resolve why logs aren’t appearing in New Relic during request handling.