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use async_trait::async_trait;
use lazy_static::lazy_static;
use prometheus::{
self, register_histogram_vec, register_int_counter_vec, Encoder, HistogramVec, IntCounterVec,
TextEncoder,
};
use std::time::{Duration, Instant};
use tide::{Next, Request, Response, Result};
// Copied from https://docs.rs/prometheus/0.12.0/src/prometheus/histogram.rs.html#885-889
#[inline]
fn duration_to_seconds(d: Duration) -> f64 {
let nanos = f64::from(d.subsec_nanos()) / 1e9;
d.as_secs() as f64 + nanos
}
lazy_static! {
static ref HTTP_CONNS_COUNTER: IntCounterVec = register_int_counter_vec!(
"http_requests_total",
"Number of processed HTTP requests",
&["code", "method", "url"]
)
.unwrap();
static ref HTTP_REQUEST_DURATION_HISTOGRAM: HistogramVec = register_histogram_vec!(
"http_request_duration_seconds",
"Duration of HTTP requests",
&["code", "method", "url"]
)
.unwrap();
}
pub struct InstrumentationMiddleware {}
#[async_trait]
impl<S> tide::Middleware<S> for InstrumentationMiddleware
where
S: Send + Sync + Clone + 'static,
{
async fn handle(&self, req: Request<S>, next: Next<'_, S>) -> Result {
let url = req.url().to_string();
let method = req.method().to_string();
// Execute the request
let instant = Instant::now();
let res = next.run(req).await;
let elapsed = duration_to_seconds(instant.elapsed());
// Get the code from the response
let code = res.status().to_string();
HTTP_CONNS_COUNTER
.with_label_values(&[&code, &method, &url])
.inc();
HTTP_REQUEST_DURATION_HISTOGRAM
.with_label_values(&[&code, &method, &url])
.observe(elapsed);
Ok(res)
}
}
pub async fn gather<S>(_: Request<S>) -> Result
where
S: Send + Sync + Clone,
{
let mut buffer: Vec<u8> = vec![];
let encoder = TextEncoder::new();
let metric_families = prometheus::gather();
encoder.encode(&metric_families, &mut buffer).unwrap();
Ok(Response::builder(200).body(buffer).build())
}
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