main.rs

use opentelemetry::global;
use opentelemetry::Key;
use opentelemetry::KeyValue;
use opentelemetry_sdk::metrics::{
    Aggregation, Instrument, PeriodicReader, SdkMeterProvider, Stream,
};
use opentelemetry_sdk::{runtime, Resource};
use std::error::Error;

fn init_meter_provider() -> opentelemetry_sdk::metrics::SdkMeterProvider {
    // for example 1
    let my_view_rename_and_unit = |i: &Instrument| {
        if i.name == "my_histogram" {
            Some(
                Stream::new()
                    .name("my_histogram_renamed")
                    .unit("milliseconds"),
            )
        } else {
            None
        }
    };

    // for example 2
    let my_view_drop_attributes = |i: &Instrument| {
        if i.name == "my_counter" {
            Some(Stream::new().allowed_attribute_keys(vec![Key::from("mykey1")]))
        } else {
            None
        }
    };

    // for example 3
    let my_view_change_aggregation = |i: &Instrument| {
        if i.name == "my_second_histogram" {
            Some(
                Stream::new().aggregation(Aggregation::ExplicitBucketHistogram {
                    boundaries: vec![0.9, 1.0, 1.1, 1.2, 1.3, 1.4, 1.5],
                    record_min_max: false,
                }),
            )
        } else {
            None
        }
    };

    let exporter = opentelemetry_stdout::MetricsExporterBuilder::default()
        // uncomment the below lines to pretty print output.
        // .with_encoder(|writer, data|
        //   Ok(serde_json::to_writer_pretty(writer, &data).unwrap()))
        .build();
    let reader = PeriodicReader::builder(exporter, runtime::Tokio).build();
    let provider = SdkMeterProvider::builder()
        .with_reader(reader)
        .with_resource(Resource::new([KeyValue::new(
            "service.name",
            "metrics-advanced-example",
        )]))
        .with_view(my_view_rename_and_unit)
        .with_view(my_view_drop_attributes)
        .with_view(my_view_change_aggregation)
        .build();
    global::set_meter_provider(provider.clone());
    provider
}

#[tokio::main]
async fn main() -> Result<(), Box<dyn Error + Send + Sync + 'static>> {
    let meter_provider = init_meter_provider();
    let meter = global::meter("mylibraryname");

    // Example 1 - Rename metric using View.
    // This instrument will be renamed to "my_histogram_renamed",
    // and its unit changed to "milliseconds"
    // using view.
    let histogram = meter
        .f64_histogram("my_histogram")
        .with_unit("ms")
        .with_description("My histogram example description")
        .init();

    // Record measurements using the histogram instrument.
    histogram.record(
        10.5,
        &[
            KeyValue::new("mykey1", "myvalue1"),
            KeyValue::new("mykey2", "myvalue2"),
            KeyValue::new("mykey3", "myvalue3"),
            KeyValue::new("mykey4", "myvalue4"),
        ],
    );

    // Example 2 - Drop unwanted attributes using view.
    let counter = meter.u64_counter("my_counter").init();

    // Record measurements using the Counter instrument.
    // Though we are passing 4 attributes here, only 1 will be used
    // for aggregation as view is configured to use only "mykey1"
    // attribute.
    counter.add(
        10,
        &[
            KeyValue::new("mykey1", "myvalue1"),
            KeyValue::new("mykey2", "myvalue2"),
            KeyValue::new("mykey3", "myvalue3"),
            KeyValue::new("mykey4", "myvalue4"),
        ],
    );

    // Example 3 - Change Aggregation configuration using View.
    // Histograms are by default aggregated using ExplicitBucketHistogram
    // with default buckets. The configured view will change the aggregation to
    // use a custom set of boundaries, and min/max values will not be recorded.
    let histogram2 = meter
        .f64_histogram("my_second_histogram")
        .with_unit("ms")
        .with_description("My histogram example description")
        .init();

    // Record measurements using the histogram instrument.
    // The values recorded are in the range of 1.2 to 1.5, warranting
    // the change of boundaries.
    histogram2.record(
        1.5,
        &[
            KeyValue::new("mykey1", "myvalue1"),
            KeyValue::new("mykey2", "myvalue2"),
            KeyValue::new("mykey3", "myvalue3"),
            KeyValue::new("mykey4", "myvalue4"),
        ],
    );

    histogram2.record(
        1.2,
        &[
            KeyValue::new("mykey1", "myvalue1"),
            KeyValue::new("mykey2", "myvalue2"),
            KeyValue::new("mykey3", "myvalue3"),
            KeyValue::new("mykey4", "myvalue4"),
        ],
    );

    histogram2.record(
        1.23,
        &[
            KeyValue::new("mykey1", "myvalue1"),
            KeyValue::new("mykey2", "myvalue2"),
            KeyValue::new("mykey3", "myvalue3"),
            KeyValue::new("mykey4", "myvalue4"),
        ],
    );

    // Metrics are exported by default every 30 seconds when using stdout exporter,
    // however shutting down the MeterProvider here instantly flushes
    // the metrics, instead of waiting for the 30 sec interval.
    meter_provider.shutdown()?;
    Ok(())
}