How to disable OpenTelemetry

[mkaszub]

Hi,
how can I control if open telemetry is enabled/disabled based on the configuration. What I want to achieve is that in some environments my metrics should not be collected in my API controllers.

I configure OpenTelemetry metrics with auto-start using the AddOpenTelemetry extension from OpenTelemetry.Extensions.Hosting.

services.AddOpenTelemetry().ConfigureResource(builder => builder
                    .AddService(serviceName: "some-service"))
                .WithMetrics(builder => builder
                        .AddMeter("my_meter")
                        .AddOtlpExporter((otlpOptions, metricReaderOptions) =>
                            {
                                otlpOptions.Endpoint = new Uri("http://some_url:4317");
                                otlpOptions.Protocol = OtlpExportProtocol.Grpc;
                            }
                        )
                );

Later in my controller's constructor I'm creating meter:
_meter = new Meter("my_meter", "1.0.0");

... and finally in one of the function I'm collecting metric

var countHistogram = _meter.CreateHistogram<int>("count");
...
countHistogram.Record(<some time>);

What would be the best approach to disable metrics collection? I was reading in spec about No-Op but I cannot find it in the library.

[cijothomas]

All metrics (traces too) are explicit opt-in - i.e metrics must be enabled by using AddMeter() API. If you want to only enable metrics in one environment, but not in another, the easiest way is by controlling AddMeter() calls. For example, you can keep the list of meter names in config file (like appsettings.json), and call AddMeter() using the names from the config. By controlling the config for each environment, you can control the metrics itself.

if (app.Environment.IsDevelopment())
{

}
else
{
AddMeter("My-meter");
}

[mkaszub]

Thanks @cijothomas . What about piece of the code that I have in controller.

var countHistogram = _meter.CreateHistogram<int>("count");
...
countHistogram.Record(<some time>);

Is it safe to call it when meter disabled? Would be great to not have "if" around all my counters/histograms.

[cijothomas]

it is absolutely fine! If the Meter is not added to the MeterProvider, then everything will "no-ops", and you dont need to do anything extra.