C#C
C#•8mo ago
ewilliams

Aspnet Instrumentation OTEL Filters

I ran into an interesting problem using the Open Telemetry packages in a dotnet 8 application. We have a service that gets hammered, roughly 3b events a month so I created a custom filter to sample specific routes. After deploying the update I noticed my should be 90% reduction only went down by about half. I did some local testing and reviewed the data only to find the filter predicate was never even invoked from a specific appliance we have out in the field. It’s an old windows CE device using HTTP 1.1. Aside from that I don’t notice anything different about the request. Unfortunately these devices can’t be updated or at least not quickly as there are several thousand out in the field. Is there a different filter mechanism I can use as apposed to the packages OTEL middleware that may happen further down stream?

builder.Services
            .AddOpenTelemetry()
            .ConfigureResource(resource => resource.AddService(DiagnosticsConfiguration.ServiceName))
            .WithTracing(tracing =>
            {
                tracing
                    .AddSource(DiagnosticsConfiguration.ServiceName)
                    .AddAspNetCoreInstrumentation(ops =>
                    {
                        //// code here is never invoked with old http client
                        ops.Filter = new RootSpanEndpointFilter("POST").Filter;
                    })
                    .AddSqlClientInstrumentation(o =>
                    {
                        o.SetDbStatementForText = true;
                        o.Filter = @object =>
                        {
                           
                           /// ….
                        };
                    })
                    .AddHttpClientInstrumentation();

                tracing.AddOtlpExporter();
            })
            .WithLogging(logging =>
            {
                logging.ConfigureResource(re => re.AddService(DiagnosticsConfiguration.ServiceName));
            });
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