gadget-sdk 0.6.2

SDK for building Blueprints and gadget on Tangle Network
Documentation 
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// This file is part of Substrate.

// Copyright (C) Parity Technologies (UK) Ltd.
// SPDX-License-Identifier: Apache-2.0

// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// 	http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.

mod sourced;

use hyper::{http::StatusCode, Request, Response};
use prometheus::{core::Collector, Encoder, TextEncoder};
use std::net::SocketAddr;

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,
};
pub use sourced::{MetricSource, SourcedCounter, SourcedGauge, SourcedMetric};

type Body = http_body_util::Full<hyper::body::Bytes>;

/// Register a `metric` within the given `registry`.
///
/// # Errors
///
/// * The `metric` is already registered.
/// * The `metric` is otherwise invalid.
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 {
    /// Hyper internal error.
    #[error(transparent)]
    Hyper(#[from] hyper::Error),

    /// Http request error.
    #[error(transparent)]
    Http(#[from] hyper::http::Error),

    /// i/o error.
    #[error(transparent)]
    Io(#[from] std::io::Error),

    /// The prometheus port is already in use.
    #[error("Prometheus port {0} already in use.")]
    PortInUse(SocketAddr),
}

async fn request_metrics(
    req: Request<hyper::body::Incoming>,
    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)
    }
}

/// Initializes the metrics context, and starts an HTTP server
/// to serve metrics.
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
}

/// Init prometheus using the given listener.
async fn init_prometheus_with_listener(
    listener: tokio::net::TcpListener,
    registry: Registry,
) -> Result<(), Error> {
    log::info!(target: "prometheus", "〽️ Prometheus exporter started at {}", listener.local_addr()?);

    let server = hyper_util::server::conn::auto::Builder::new(hyper_util::rt::TokioExecutor::new());

    loop {
        let io = match listener.accept().await {
            Ok((sock, _)) => hyper_util::rt::TokioIo::new(sock),
            Err(e) => {
                log::debug!(target: "prometheus", "Error accepting connection: {:?}", e);
                continue;
            }
        };

        let registry = registry.clone();

        let conn = server
            .serve_connection_with_upgrades(
                io,
                hyper::service::service_fn(move |req| request_metrics(req, registry.clone())),
            )
            .into_owned();

        #[allow(clippy::let_underscore_future)]
        let _ = tokio::spawn(async move {
            if let Err(err) = conn.await {
                log::debug!(target: "prometheus", "connection error: {:?}", err);
            }
        });
    }
}

#[cfg(test)]
#[allow(clippy::let_underscore_future, clippy::needless_return)]
mod tests {
    use super::*;
    use http_body_util::BodyExt;
    use hyper::Uri;
    use hyper_util::{client::legacy::Client, rt::TokioExecutor};

    const METRIC_NAME: &str = "test_test_metric_name_test_test";

    #[tokio::test]
    async fn prometheus_works() {
        let listener = tokio::net::TcpListener::bind("127.0.0.1:0")
            .await
            .expect("Creates listener");

        let local_addr = listener.local_addr().expect("Returns the local addr");

        let registry = Registry::default();
        let _ = register(
            prometheus::Counter::new(METRIC_NAME, "yeah").expect("Creates test counter"),
            &registry,
        )
        .expect("Registers the test metric");

        let _ = tokio::spawn(init_prometheus_with_listener(listener, registry));

        let client = Client::builder(TokioExecutor::new()).build_http::<Body>();

        let res = client
            .get(Uri::try_from(&format!("http://{}/metrics", local_addr)).expect("Parses URI"))
            .await
            .expect("Requests metrics");

        assert!(res.status().is_success());

        let buf = res
            .into_body()
            .collect()
            .await
            .expect("Failed to read HTTP body")
            .to_bytes();
        let body = String::from_utf8(buf.to_vec()).expect("Converts body to String");

        assert!(body.contains(&format!("{} 0", METRIC_NAME)));
    }
}