How to set default attributes for metrics ?

[alefcarlos]

Is there a way to add default attribute for all metrics ?

I added attributes to ResourceBuilder:

var defaultAttributes = new TagList
{
    { "var1", "value1" },
    { "var2", "value2" },
};

var resourceBuilder = ResourceBuilder
                        .CreateDefault()
                        .AddAttributes(defaultAttributes)
                        .AddService("WebApi1", serviceVersion: assemblyVersion, serviceInstanceId: Environment.MachineName);

And then configured OpenTelemetryMetrics to use console exporter to a quick test:

services.AddOpenTelemetryMetrics(options =>
            {
                options.SetResourceBuilder(resourceBuilder);
                options.AddMeter("Super.WebApi");
                options.AddConsoleExporter();
            });

And at Controller:

var attributes = new TagList
{
    { "my_label", "value1" },
};
_metrics.TransactionAuthorized.Add(1, attributes);

I'd expect to see my_label, var1 and var2 on Console, but only my_label was shown:

Export TransactionAuthorized, Meter: Super.WebApi/1.0.0
(2022-06-02T19:32:47.5247319Z, 2022-06-02T19:34:26.6444907Z] my_label: value1 LongSum
Value: 7

Is there anything I could do ?

[cijothomas]

Resource is a way to model this. (The console exporter for metrics is ignoring resource - its a bug. will send a fix).
But you must be using something other than Console for your actual service right? Like an OTLP exporter. it should already support Resources.

[alefcarlos]

I tried OtlpExporter + Prometheus:

Only my_label was ingested.

[cijothomas]

But where can I view the matrics data

The example I shared has OTel Collecting with logging output enabled - so it output metrics to console, which should show resources.

(Prometheus does not support resource yet, its pending spec.)

[alefcarlos]

I get it. I can see the resources attributes.

I should open an issue/discussion on Dynatrace exporter to understand that.

Thank you so much, @cijothomas !

[xavirec]

Is there any plan to implement this in the PrometheusExporter?

[cijothomas]

Is there any plan to implement this in the PrometheusExporter?

Its a spec question. See experimental version here : https://github.com/open-telemetry/opentelemetry-specification/blob/main/specification/metrics/datamodel.md#prometheus-compatibility