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use hyper::{
http::StatusCode,
server::Server,
service::{make_service_fn, service_fn},
Body, Request, Response,
};
pub use prometheus::{
self,
core::{
AtomicF64 as F64, AtomicI64 as I64, AtomicU64 as U64, GenericCounter as Counter,
GenericCounterVec as CounterVec, GenericGauge as Gauge, GenericGaugeVec as GaugeVec,
},
exponential_buckets, Error as PrometheusError, Histogram, HistogramOpts, HistogramVec, Opts,
Registry,
};
use prometheus::{core::Collector, Encoder, TextEncoder};
use std::net::SocketAddr;
mod sourced;
pub use sourced::{MetricSource, SourcedCounter, SourcedGauge, SourcedMetric};
pub fn register<T: Clone + Collector + 'static>(
metric: T,
registry: &Registry,
) -> Result<T, PrometheusError> {
registry.register(Box::new(metric.clone()))?;
Ok(metric)
}
#[derive(Debug, thiserror::Error)]
pub enum Error {
#[error(transparent)]
Hyper(#[from] hyper::Error),
#[error(transparent)]
Http(#[from] hyper::http::Error),
#[error(transparent)]
Io(#[from] std::io::Error),
#[error("Prometheus port {0} already in use.")]
PortInUse(SocketAddr),
}
async fn request_metrics(req: Request<Body>, registry: Registry) -> Result<Response<Body>, Error> {
if req.uri().path() == "/metrics" {
let metric_families = registry.gather();
let mut buffer = vec![];
let encoder = TextEncoder::new();
encoder.encode(&metric_families, &mut buffer).unwrap();
Response::builder()
.status(StatusCode::OK)
.header("Content-Type", encoder.format_type())
.body(Body::from(buffer))
.map_err(Error::Http)
} else {
Response::builder()
.status(StatusCode::NOT_FOUND)
.body(Body::from("Not found."))
.map_err(Error::Http)
}
}
pub async fn init_prometheus(prometheus_addr: SocketAddr, registry: Registry) -> Result<(), Error> {
let listener = tokio::net::TcpListener::bind(&prometheus_addr)
.await
.map_err(|_| Error::PortInUse(prometheus_addr))?;
init_prometheus_with_listener(listener, registry).await
}
async fn init_prometheus_with_listener(
listener: tokio::net::TcpListener,
registry: Registry,
) -> Result<(), Error> {
let listener = hyper::server::conn::AddrIncoming::from_listener(listener)?;
log::info!("〽️ Prometheus exporter started at {}", listener.local_addr());
let service = make_service_fn(move |_| {
let registry = registry.clone();
async move {
Ok::<_, hyper::Error>(service_fn(move |req: Request<Body>| {
request_metrics(req, registry.clone())
}))
}
});
let server = Server::builder(listener).serve(service);
let result = server.await.map_err(Into::into);
result
}
#[cfg(test)]
mod tests {
use super::*;
use hyper::{Client, Uri};
#[test]
fn prometheus_works() {
const METRIC_NAME: &str = "test_test_metric_name_test_test";
let runtime = tokio::runtime::Runtime::new().expect("Creates the runtime");
let listener = runtime
.block_on(tokio::net::TcpListener::bind("127.0.0.1:0"))
.expect("Creates listener");
let local_addr = listener.local_addr().expect("Returns the local addr");
let registry = Registry::default();
register(
prometheus::Counter::new(METRIC_NAME, "yeah").expect("Creates test counter"),
®istry,
)
.expect("Registers the test metric");
runtime.spawn(init_prometheus_with_listener(listener, registry));
runtime.block_on(async {
let client = Client::new();
let res = client
.get(Uri::try_from(&format!("http://{}/metrics", local_addr)).expect("Parses URI"))
.await
.expect("Requests metrics");
let buf = hyper::body::to_bytes(res).await.expect("Converts body to bytes");
let body = String::from_utf8(buf.to_vec()).expect("Converts body to String");
assert!(body.contains(&format!("{} 0", METRIC_NAME)));
});
}
}