Sentry client does not flush metrics unless bound to a hub

[untitaker]

I would like to use the Rust SDK from within vector to send metrics, without instrumenting the rest of the app.

This example does not send anything:

use sentry::{metrics::Metric, ClientOptions};
use std::time::Duration;

# does not send any metric

fn main() {
    let client = sentry::Client::from_config("...");
    let metric = Metric::incr("hello-with-global", 2.0).finish();
    client.add_metric(metric);
    client.flush(Some(Duration::from_secs(1)));
}

I can verify using mitmproxy that there's no HTTP request leaving the process.

the only version that works is one where MetricBuilder::send and sentry::init are used:

# sends a metric

fn main() {
    let _guard = sentry::init("...");
    Metric::incr("hello", 2.0).send();
}

SDK version 0.32.1

[mitsuhiko]

Point of reference here: the other SDKs force the flusher to flush when the client flushes explicitly.

[syphar]

is there a workaround for this issue?
I'm not 100% certain I'm hitting it, but I want to send metrics without having to use the global hub
( we have a small service that converts logs to sentry errors & messages )

that wasn't the issue, I can use Client::add_metric directly, and data is transferred. I didn't test explicit flushing