Update opentelemetry to 0.19

[jaysonsantos]

This is a stacked PR with #9.
It should be a clean update, as opentelemetry 0.19 did not break any API.

[djc]

@jtescher ping? What is this waiting for?

[Oliboy50]

@djc I would say that this is waiting at least for #9

BTW, me too, I would love to see an opentelemetry 0.19 compatible release of tracing-opentelemetry soon... but I understand that moving sources from another repository may have slow things down here... good luck contributors 💪

[tomkarw]

This seems like a drive-by change, is there some reason behind it other than personal preference? Does it allow removing async-trait from dependencies?

[jaysonsantos]

@tomkarw this is from #9 which is an exact backport from the main repo, I am not the original author of it

[tomkarw]

Got it. It's a nitpick, so I don't think chasing the original author makes sense.

[fenollp]

Hi there, looks like this PR needs rebasing! :)

[jaysonsantos]

@fenollp this pr is stacked with the 0.18 #9 , I have to wait for that one to be merged first

[liamwh]

Perhaps it's also a good idea to include an example with OpenTelemetry OTLP in this PR also, to ensure compilation checks with OpenTelemetry OTLP?

For example, something like the following might serve as a good best practice example base case:

use opentelemetry_otlp::WithExportConfig;
use tracing_subscriber::{prelude::__tracing_subscriber_SubscriberExt, Layer};

const OTEL_EXPORTER_OTLP_ENDPOINT_ENV_VAR: &str = "OTEL_EXPORTER_OTLP_ENDPOINT";
const OTEL_EXPORTER_OTLP_ENDPOINT_DEFAULT: &str = "http://localhost:4317";

const OBSERVABILITY_SERVICE_NAME_ENV_VAR: &str = "OBSERVABILITY_SERVICE_NAME";
const OBSERVABILITY_SERVICE_NAME_DEFAULT: &str = "veloxide-server";

#[tracing::instrument]
pub async fn configure_observability() -> std::result::Result<(), crate::error::Error> {
    let otel_exporter_endpoint =
        dotenvy::var(OTEL_EXPORTER_OTLP_ENDPOINT_ENV_VAR).unwrap_or_else(|_| {
            tracing::warn!(
                "{} Env var not set, using default",
                OTEL_EXPORTER_OTLP_ENDPOINT_DEFAULT
            );
            OTEL_EXPORTER_OTLP_ENDPOINT_DEFAULT.to_string()
        });

    let observability_service_name = dotenvy::var(OBSERVABILITY_SERVICE_NAME_ENV_VAR)
        .unwrap_or_else(|_| OBSERVABILITY_SERVICE_NAME_DEFAULT.to_string());

    let tracer = opentelemetry_otlp::new_pipeline()
        .tracing()
        .with_exporter(
            opentelemetry_otlp::new_exporter()
                .tonic()
                .with_endpoint(otel_exporter_endpoint),
        )
        .with_trace_config(opentelemetry::sdk::trace::config().with_resource(
            opentelemetry::sdk::Resource::new(vec![opentelemetry::KeyValue::new(
                "service.name",
                observability_service_name,
            )]),
        ))
        .install_batch(opentelemetry::runtime::Tokio)?;

    // Create a tracing layer with the configured tracer
    let telemetry_layer = tracing_opentelemetry::layer().with_tracer(tracer);

    let filter = tracing_subscriber::EnvFilter::from_default_env();

    // Use the tracing subscriber `Registry`, or any other subscriber
    // that impls `LookupSpan`
    let subscriber = tracing_subscriber::Registry::default()
        .with(telemetry_layer)
        .with(
            tracing_subscriber::fmt::layer()
                .with_writer(std::io::stdout)
                .with_filter(filter),
        );

    Ok(tracing::subscriber::set_global_default(subscriber)?)
}

[tekul]

@liamwh I think opentelemetry-rust supports OTEL_EXPORTER_OTLP_ENDPOINT and also OTEL_SERVICE_NAME out of the box, so these could be used to simplify the example.

[fenollp]

@jaysonsantos The other PR has been merged :)