Metrics page may appear blank after a few seconds.

[mhdimsy]

What is the question?

Hello everyone.
The metrics page may appear blank after a few seconds.
Then Prometheus shows the job is up, but metrics are not scraped.

My config is

services.AddOpenTelemetry()
.ConfigureResource(resource => resource.AddService("backend"))
.WithMetrics(builder => builder
.AddMeter(FormStepHandlerMeter.name)
                    .AddMeter("Microsoft.AspNetCore.Hosting")
                    .AddMeter("Microsoft.AspNetCore.Http.Connections")
                    .AddMeter("Microsoft.AspNetCore.Routing")
                    .AddMeter("Microsoft.AspNetCore.Diagnostics")
                    .AddMeter("Microsoft.AspNetCore.RateLimiting")
                    .AddAspNetCoreInstrumentation()
                    .AddRuntimeInstrumentation()
                    .AddPrometheusExporter()
                )

I use dotnet 6 and this packages:
OpenTelemetry.Exporter.Console 1.9.0
OpenTelemetry.Exporter.Prometheus.AspNetCore 1.9.0-beta.1
OpenTelemetry.Extensions.Hosting 1.9.0
OpenTelemetry.Instrumentation.AspNetCore 1.9.0
OpenTelemetry.Instrumentation.EntityFrameworkCore 1.0.0-beta.12
OpenTelemetry.Instrumentation.Http 1.9.0
OpenTelemetry.Instrumentation.Runtime 1.9.0
OpenTelemetry.Instrumentation.SqlClient 1.9.0-beta.1

Even though nothing is being collected, it takes 259.968 to complete(last scraping).

[cijothomas]

Is the scraping endpoint setup as well? (The code snippet above does not indicate so...)
https://github.com/open-telemetry/opentelemetry-dotnet/blob/main/examples/AspNetCore/Program.cs#L168

[mhdimsy]

Yes
In startup.cs file this line exist.
Just the first few seconds it works fine, but then it stops sending.
please see the image

[mhdimsy]

FYI:
I activate console exporter
While the console is printing the metrics correctly, the issue I mentioned still exists.

[Kielek]

@mhdimsy, please give a chance to OpenTelemetry.Exporter.Prometheus.AspNetCore 1.9.0-beta.2. It was released yesterday.

[mhdimsy]

@Kielek , Thanks it works.
But AddAspNetCoreInstrumentation not has http_server_active_requests metrics, this is correct?

[Kielek]

@mhdimsy, please check https://github.com/open-telemetry/opentelemetry-dotnet-contrib/blob/Instrumentation.AspNetCore-1.9.0/src/OpenTelemetry.Instrumentation.AspNetCore/README.md#metrics

I am closing this as the issue was solved. Please create separate one if you fins some problems with metrics.