1
  2
  3
  4
  5
  6
  7
  8
  9
 10
 11
 12
 13
 14
 15
 16
 17
 18
 19
 20
 21
 22
 23
 24
 25
 26
 27
 28
 29
 30
 31
 32
 33
 34
 35
 36
 37
 38
 39
 40
 41
 42
 43
 44
 45
 46
 47
 48
 49
 50
 51
 52
 53
 54
 55
 56
 57
 58
 59
 60
 61
 62
 63
 64
 65
 66
 67
 68
 69
 70
 71
 72
 73
 74
 75
 76
 77
 78
 79
 80
 81
 82
 83
 84
 85
 86
 87
 88
 89
 90
 91
 92
 93
 94
 95
 96
 97
 98
 99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134

extern crate failure;
extern crate serde_json;
use http::StatusCode;
use hyper::service::{make_service_fn, service_fn};
use hyper::Client;
use hyper::{body, Body, Request, Response, Server};
use log::{debug, error, info, trace, warn};
use serde::de::DeserializeOwned;
use std::sync::Arc;
mod render_to_prometheus;
pub use render_to_prometheus::PrometheusMetric;
mod metric_type;
pub use metric_type::MetricType;
use std::future::Future;
use std::net::SocketAddr;

#[inline]
async fn extract_body(resp: hyper::client::ResponseFuture) -> Result<String, failure::Error> {
    let resp = resp.await?;
    debug!("response == {:?}", resp);

    let (_parts, body) = resp.into_parts();
    let complete_body = body::to_bytes(body).await?;

    let s = String::from_utf8(complete_body.to_vec())?;
    trace!("extracted text == {}", s);

    Ok(s)
}

pub async fn create_string_future_from_hyper_request(
    request: hyper::Request<hyper::Body>,
) -> Result<String, failure::Error> {
    let https = hyper_rustls::HttpsConnector::new();
    let client = Client::builder().build::<_, hyper::Body>(https);

    Ok(extract_body(client.request(request)).await?)
}

pub async fn create_deserialize_future_from_hyper_request<T>(
    request: hyper::Request<hyper::Body>,
) -> Result<T, failure::Error>
where
    T: DeserializeOwned + std::fmt::Debug,
{
    let text = create_string_future_from_hyper_request(request).await?;
    let t = serde_json::from_str(&text)?;
    debug!("deserialized object == {:?}", t);
    Ok(t)
}

async fn serve_function<O, F, Fut>(
    req: Request<Body>,
    f: F,
    options: Arc<O>,
) -> Result<Response<Body>, hyper::Error>
where
    F: FnOnce(Request<Body>, Arc<O>) -> Fut,
    Fut: Future<Output = Result<String, failure::Error>>,
    O: std::fmt::Debug,
{
    trace!(
        "serve_function:: req.uri() == {}, req.method() == {}",
        req.uri().path(),
        req.method()
    );
    if req.uri().path() != "/metrics" {
        Ok(Response::builder()
            .status(StatusCode::NOT_FOUND)
            .body(hyper::Body::empty())
            .unwrap())
    } else if req.method() != "GET" {
        Ok(Response::builder()
            .status(StatusCode::METHOD_NOT_ALLOWED)
            .body(hyper::Body::empty())
            .unwrap())
    } else {
        // everything is ok, let's call the supplied future
        trace!("serve_function:: options == {:?}", options);

        Ok(match f(req, options).await {
            Ok(response) => Response::new(Body::from(response)),
            Err(err) => {
                warn!("internal server error == {:?}", err);

                Response::builder()
                    .status(StatusCode::INTERNAL_SERVER_ERROR)
                    .body(Body::from(err.to_string()))
                    .unwrap()
            }
        })
    }
}

async fn run_server<O, F, Fut>(addr: SocketAddr, options: Arc<O>, f: F) -> Result<(), hyper::Error>
where
    F: FnOnce(Request<Body>, Arc<O>) -> Fut + Send + Clone + Sync + 'static,
    Fut: Future<Output = Result<String, failure::Error>> + Send + 'static,
    O: std::fmt::Debug + Sync + Send + 'static,
{
    info!("Listening on http://{}", addr);

    let f = f.clone();
    let options = options.clone();

    let make_service = make_service_fn(move |_| {
        let f = f.clone();
        let options = options.clone();

        async move {
            Ok::<_, hyper::Error>(service_fn(move |req| {
                serve_function(req, f.clone(), options.clone())
            }))
        }
    });

    let serve_future = Server::bind(&addr).serve(make_service);

    serve_future.await
}

pub async fn render_prometheus<O, F, Fut>(addr: SocketAddr, options: O, f: F)
where
    F: FnOnce(Request<Body>, Arc<O>) -> Fut + Send + Clone + Sync + 'static,
    Fut: Future<Output = Result<String, failure::Error>> + Send + 'static,
    O: std::fmt::Debug + Sync + Send + 'static,
{
    let o = Arc::new(options);

    let _ = run_server(addr, o, f).await.map_err(|err| {
        error!("{:?}", err);
        eprintln!("Server failure: {:?}", err)
    });
}