I have a problem with OpenTelemetry configuration in my .NET 8 web app.

Logs are visible in the Grafana/Loki application, but I see only one label service_name with value unknown_service:dotnet.
When I configure Serilog to write logs directly to Loki (.WriteTo.GrafanaLoki(...)), everything works fine.

How to properly configure the entire application to be able to define my own labels in Loki?

My configuration:

Application (.NET):

OpenTelemetryBuilder builder
     = webAppBuilder.Services.AddOpenTelemetry().ConfigureResource(
         resBuilder => resBuilder.AddService(
            serviceName: resource.Name,
            serviceVersion: resource.Version,
            autoGenerateServiceInstanceId: false,
            serviceInstanceId: Environment.MachineName
        ));

builder.WithTracing(tracing => {
           tracing.AddSource("MyApp")
                  .AddAspNetCoreInstrumentation(o =>
                   {
                     o.RecordException = true;
                   })
                  .AddHttpClientInstrumentation(h => h.RecordException = true)
                  .SetSampler(new AlwaysOnSampler())
                  .SetErrorStatusOnException()
                  .AddOtlpExporter(); // GRPC: http://localhost:4317

builder.WithMetrics(metrics => {
           metrics.AddMeter("MyApp")
                  .AddMeter(DiagnosticHeaders.DefaultListenerName)
                  .SetExemplarFilter(ExemplarFilterType.TraceBased)
                  .AddRuntimeInstrumentation()
                  .AddHttpClientInstrumentation()
                  .AddAspNetCoreInstrumentation()
                  .AddProcessInstrumentation()
                  .AddOtlpExporter(); // GRPC: http://localhost:4317

webAppBuilder.Services.AddSerilog(
    (serviceProvider, configuration) =>
    {
      configuration.Enrich.WithProcessId()
                   .Enrich.WithThreadId()
                   .Enrich.FromLogContext()
                   .MinimumLevel.Verbose()
                   .WriteTo.AddConsoleSink()
                   .WriteTo.OpenTelemetry() // GRPC: http://localhost:4317
    }
);

otel-collector.yaml (on Docker from image otel/opentelemetry-collector:latest):

receivers:
  otlp:
    protocols:
      grpc:
        endpoint: 0.0.0.0:4317
      http:
        endpoint: 0.0.0.0:4318

processors:
  batch:
    timeout: 3s                # Batch data for up to 3 seconds
    send_batch_size: 1000      # Number of spans or metrics per batch

exporters:
  prometheus:
    endpoint: ":9201"          # Prometheus remote write endpoint
    send_timestamps: true
    metric_expiration: 180m
    enable_open_metrics: true
  otlp/tempo:
    endpoint: tempo:4317       # Endpoint for Tempo to send traces
    tls:
      insecure: true
  otlphttp/loki:
    endpoint: http://loki:3100/otlp   # Endpoint for Loki to send logs
    tls:
      insecure: true 

extensions:
  health_check:

service:
  extensions: [health_check]
  pipelines:
    traces:
      receivers: [otlp]
      processors: [batch]
      exporters: [otlp/tempo]
    metrics:
      receivers: [otlp]
      processors: [batch]
      exporters: [prometheus]
    logs:
      receivers: [otlp]
      processors: [batch]
      exporters: [otlphttp/loki]

Loki-config.yaml (on Docker from image grafana/loki:3.1.0)

limits_config:
  allow_structured_metadata: true