Should weather.days.freezing appear on /metrics if I set "UseMetricsExporter": "prometheus"

[dutts]

As per the title really, I've been struggling with adding custom metrics to my own asp.net 8 projects so I thought I'd take a look at Examples.AspNetCore but I'm seeing the same thing.

If I build and run Examples.AspNetCore with "UseMetricsExporter": "prometheus", in appsettings.json I can see loads of lines of metrics being outputted on \metrics

# TYPE process_runtime_dotnet_gc_collections_count_total counter
# HELP process_runtime_dotnet_gc_collections_count_total Number of garbage collections that have occurred since process start.
process_runtime_dotnet_gc_collections_count_total{otel_scope_name="OpenTelemetry.Instrumentation.Runtime",otel_scope_version="1.5.1.0",generation="gen2"} 0 1705337358141
process_runtime_dotnet_gc_collections_count_total{otel_scope_name="OpenTelemetry.Instrumentation.Runtime",otel_scope_version="1.5.1.0",generation="gen1"} 0 1705337358141
process_runtime_dotnet_gc_collections_count_total{otel_scope_name="OpenTelemetry.Instrumentation.Runtime",otel_scope_version="1.5.1.0",generation="gen0"} 0 1705337358141
# TYPE process_runtime_dotnet_gc_objects_size_bytes gauge
# UNIT process_runtime_dotnet_gc_objects_size_bytes bytes
# HELP process_runtime_dotnet_gc_objects_size_bytes Count of bytes currently in use by objects in the GC heap that haven't been collected yet. Fragmentation and other GC committed memory pools are excluded.
process_runtime_dotnet_gc_objects_size_bytes{otel_scope_name="OpenTelemetry.Instrumentation.Runtime",otel_scope_version="1.5.1.0"} 13280328 1705337358141
...

but even if I hit

curl https://localhost:5001/weatherforecast

I can see the freezingDaysCounter being incremented under the debugger, but I never see any weather.days.freezing metric appearing on the metrics endpoint.

What am I doing wrong? This is the same thing I'm seeing with my own custom metrics.

TIA

Rich

[dutts]

I'm not quite sure why but when I try again this morning with the same (unchanged code) those metrics are now appearing, so will close this off.

For info, it's the .AddMeter(Instrumentation.MeterName) call in the metrics builder in Program.cs which is doing the work to add this custom metric into the output. This is what I was missing from my own personal projects.