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| 1 | +//! Serves an HTTP health server. |
| 2 | +//! |
| 3 | +//! * `GET /ready` -- returns 200 when the proxy is ready to participate in meshed |
| 4 | +//! traffic. |
| 5 | +//! * `GET /live` -- returns 200 when the proxy is live. |
| 6 | +
|
| 7 | +use futures::future; |
| 8 | +use http::StatusCode; |
| 9 | +use hyper::{ |
| 10 | + body::{Body, HttpBody}, |
| 11 | + Request, Response, |
| 12 | +}; |
| 13 | +use linkerd_app_core::Error; |
| 14 | +use std::{ |
| 15 | + future::Future, |
| 16 | + pin::Pin, |
| 17 | + task::{Context, Poll}, |
| 18 | +}; |
| 19 | + |
| 20 | +mod readiness; |
| 21 | + |
| 22 | +pub use self::readiness::{Latch, Readiness}; |
| 23 | + |
| 24 | +#[derive(Clone)] |
| 25 | +pub struct Health { |
| 26 | + ready: Readiness, |
| 27 | +} |
| 28 | + |
| 29 | +pub type ResponseFuture = |
| 30 | + Pin<Box<dyn Future<Output = Result<Response<Body>, Error>> + Send + 'static>>; |
| 31 | + |
| 32 | +impl Health { |
| 33 | + pub fn new(ready: Readiness) -> Self { |
| 34 | + Self { ready } |
| 35 | + } |
| 36 | + |
| 37 | + fn ready_rsp(&self) -> Response<Body> { |
| 38 | + if self.ready.is_ready() { |
| 39 | + Response::builder() |
| 40 | + .status(StatusCode::OK) |
| 41 | + .header(http::header::CONTENT_TYPE, "text/plain") |
| 42 | + .body("ready\n".into()) |
| 43 | + .expect("builder with known status code must not fail") |
| 44 | + } else { |
| 45 | + Response::builder() |
| 46 | + .status(StatusCode::SERVICE_UNAVAILABLE) |
| 47 | + .body("not ready\n".into()) |
| 48 | + .expect("builder with known status code must not fail") |
| 49 | + } |
| 50 | + } |
| 51 | + |
| 52 | + fn live_rsp() -> Response<Body> { |
| 53 | + Response::builder() |
| 54 | + .status(StatusCode::OK) |
| 55 | + .header(http::header::CONTENT_TYPE, "text/plain") |
| 56 | + .body("live\n".into()) |
| 57 | + .expect("builder with known status code must not fail") |
| 58 | + } |
| 59 | + |
| 60 | + fn not_found() -> Response<Body> { |
| 61 | + Response::builder() |
| 62 | + .status(http::StatusCode::NOT_FOUND) |
| 63 | + .body(Body::empty()) |
| 64 | + .expect("builder with known status code must not fail") |
| 65 | + } |
| 66 | +} |
| 67 | + |
| 68 | +impl<B> tower::Service<http::Request<B>> for Health |
| 69 | +where |
| 70 | + B: HttpBody + Send + Sync + 'static, |
| 71 | + B::Error: Into<Error>, |
| 72 | + B::Data: Send, |
| 73 | +{ |
| 74 | + type Response = http::Response<Body>; |
| 75 | + type Error = Error; |
| 76 | + type Future = ResponseFuture; |
| 77 | + |
| 78 | + fn poll_ready(&mut self, _: &mut Context<'_>) -> Poll<Result<(), Self::Error>> { |
| 79 | + Poll::Ready(Ok(())) |
| 80 | + } |
| 81 | + |
| 82 | + fn call(&mut self, req: Request<B>) -> Self::Future { |
| 83 | + match req.uri().path() { |
| 84 | + "/live" => Box::pin(future::ok(Self::live_rsp())), |
| 85 | + "/ready" => Box::pin(future::ok(self.ready_rsp())), |
| 86 | + _ => Box::pin(future::ok(Self::not_found())), |
| 87 | + } |
| 88 | + } |
| 89 | +} |
| 90 | + |
| 91 | +#[cfg(test)] |
| 92 | +mod tests { |
| 93 | + use super::*; |
| 94 | + use http::method::Method; |
| 95 | + use std::time::Duration; |
| 96 | + use tokio::time::timeout; |
| 97 | + use tower::util::ServiceExt; |
| 98 | + |
| 99 | + const TIMEOUT: Duration = Duration::from_secs(1); |
| 100 | + |
| 101 | + #[tokio::test] |
| 102 | + async fn ready_when_latches_dropped() { |
| 103 | + let (r, l0) = Readiness::new(); |
| 104 | + let l1 = l0.clone(); |
| 105 | + |
| 106 | + let health = Health::new(r); |
| 107 | + macro_rules! call { |
| 108 | + () => {{ |
| 109 | + let r = Request::builder() |
| 110 | + .method(Method::GET) |
| 111 | + .uri("http://0.0.0.0/ready") |
| 112 | + .body(Body::empty()) |
| 113 | + .unwrap(); |
| 114 | + let f = health.clone().oneshot(r); |
| 115 | + timeout(TIMEOUT, f).await.expect("timeout").expect("call") |
| 116 | + }}; |
| 117 | + } |
| 118 | + |
| 119 | + assert_eq!(call!().status(), StatusCode::SERVICE_UNAVAILABLE); |
| 120 | + |
| 121 | + drop(l0); |
| 122 | + assert_eq!(call!().status(), StatusCode::SERVICE_UNAVAILABLE); |
| 123 | + |
| 124 | + drop(l1); |
| 125 | + assert_eq!(call!().status(), StatusCode::OK); |
| 126 | + } |
| 127 | +} |
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