comprehensive_http 0.5.1

A harness for creating consistently-shaped servers will less boilerplate
Documentation 
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
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189

//! HTTP server meant to serve diagnostics for a [`comprehensive`] server.
//!
//! This collects all other resources in the assembly that implement and
//! expose [`comprehensive_traits::http_diag::HttpDiagHandler`] and serves
//! them on a common HTTP server.
//!
//! [`comprehensive_traits::http_diag::HttpDiagHandler`]: https://docs.rs/comprehensive_traits/latest/comprehensive_traits/http_diag/trait.HttpDiagHandler.html

use axum::Router;
use axum::extract::State;
use axum::response::IntoResponse;
use comprehensive::ResourceDependencies;
use comprehensive::health::HealthReporter;
use comprehensive::v1::{AssemblyRuntime, Resource, resource};
use comprehensive_traits::http_diag::{Body, HttpDiagHandler, HttpDiagHandlerInstaller};
use prometheus::Encoder;
use std::sync::Arc;
use std::task::{Context, Poll};

use crate::server::HttpServingInstance;

async fn serve_metrics_page() -> impl axum::response::IntoResponse {
    let encoder = prometheus::TextEncoder::new();

    let metric_families = prometheus::gather();
    let mut buffer = vec![];
    encoder.encode(&metric_families, &mut buffer).unwrap();

    let mut res = buffer.into_response();
    if let Ok(hv) = encoder.format_type().try_into() {
        res.headers_mut().insert("Content-Type", hv);
    }
    res
}

async fn serve_health_page(
    State(state): State<Arc<HealthReporter>>,
) -> Result<axum::body::Bytes, http::StatusCode> {
    if state.is_healthy() {
        Ok("OK\r\n".into())
    } else {
        Err(http::StatusCode::INTERNAL_SERVER_ERROR)
    }
}

#[doc(hidden)]
#[derive(clap::Args, Debug)]
#[group(skip)]
pub struct Args {
    #[arg(long, default_value = "/metrics")]
    metrics_path: String,

    #[arg(long, default_value = "/healthz")]
    health_path: String,
}

#[doc(hidden)]
#[derive(ResourceDependencies)]
pub struct DiagInstanceDependencies {
    health: Arc<HealthReporter>,
    handlers: Vec<Arc<dyn HttpDiagHandler>>,
}

#[doc(hidden)]
#[derive(HttpServingInstance)]
#[flag_prefix = "diag-"]
pub struct DiagInstance(#[router] Router);

struct Installer(Option<Router<Arc<HealthReporter>>>);

struct DiagOps;

impl comprehensive_traits::http_diag::DiagRequestExtra for DiagOps {
    fn get_original_uri<'a>(&self, req: &'a http::Request<Body>) -> Option<&'a http::Uri> {
        req.extensions().get::<axum::extract::OriginalUri>().map(|v| &**v)
    }
}

#[derive(Clone, Debug)]
struct AdaptDiagService<T>(T);

impl<T> tower_service::Service<http::Request<Body>> for AdaptDiagService<T>
where
    T: tower_service::Service<comprehensive_traits::http_diag::DiagRequest>,
{
    type Response = T::Response;
    type Error = T::Error;
    type Future = T::Future;

    fn poll_ready(&mut self, cx: &mut Context<'_>) -> Poll<Result<(), T::Error>> {
        self.0.poll_ready(cx)
    }

    fn call(&mut self, req: http::Request<Body>) -> Self::Future {
        self.0.call(comprehensive_traits::http_diag::DiagRequest::new(req, &DiagOps))
    }
}

impl HttpDiagHandlerInstaller for Installer {
    #[allow(deprecated)]
    fn nest_service(&mut self, path: &str, service: comprehensive_traits::http_diag::Service) {
        let app = self.0.take().unwrap().nest_service(path, service);
        self.0 = Some(app);
    }

    fn nest_diag_service(&mut self, path: &str, service: comprehensive_traits::http_diag::DiagService) {
        let app = self.0.take().unwrap().nest_service(path, AdaptDiagService(service));
        self.0 = Some(app);
    }
}

#[resource]
impl Resource for DiagInstance {
    const NAME: &str = "Diagnostics HTTP server";

    fn new(
        d: DiagInstanceDependencies,
        args: Args,
        _: &mut AssemblyRuntime<'_>,
    ) -> Result<Arc<Self>, std::convert::Infallible> {
        let mut app = Router::new();
        if !args.metrics_path.is_empty() {
            app = app.route(&args.metrics_path, axum::routing::get(serve_metrics_page));
        }
        if !args.health_path.is_empty() {
            app = app.route(&args.health_path, axum::routing::get(serve_health_page));
        }
        let mut installer = Installer(Some(app));
        for handler in d.handlers {
            handler.install_handlers(&mut installer);
        }
        let Installer(app) = installer;
        Ok(Arc::new(Self(app.unwrap().with_state(d.health))))
    }
}

/// HTTP server meant to serve diagnostics for a [`comprehensive`] server.
///
/// Depend on this [`Resource`] in a [`comprehensive::Assembly`] to get
/// an HTTP server that publishes Prometheus metrics.
///
/// # Command line flags
///
/// | Flag                     | Default    | Meaning                 |
/// |--------------------------|------------|-------------------------|
/// | `--diag-http_port`       | *none*     | TCP port number for insecure HTTP server. If unset, plain HTTP is not served. |
/// | `--diag-http_bind_addr`  | `::`       | Binding IP address for HTTP. Used only if `--http_port` is set. |
/// | `--diag-https_port`      | *none*     | TCP port number for secure HTTP server. If unset, HTTPS is not served. |
/// | `--diag-https_bind_addr` | `::`       | Binding IP address for HTTPS. Used only if `--https_port` is set. |
/// | `--metrics_path`         | `/metrics` | HTTP and/or HTTPS path where metrics are served. Set to empty to disable. |
/// | `--health_path`          | `/healthz` | HTTP and/or HTTPS path where health status is served. Set to empty to disable. |
pub type HttpServer = crate::server::HttpServer<DiagInstance>;

#[cfg(test)]
mod tests {
    use prometheus::register_int_counter;
    use tower_service::Service;

    use super::*;

    #[derive(comprehensive::ResourceDependencies)]
    struct NotValidForServingShouldUseHttpServer {
        i: std::sync::Arc<DiagInstance>,
    }

    #[tokio::test]
    async fn metrics() {
        let argv = vec!["cmd"];
        let assembly =
            comprehensive::Assembly::<NotValidForServingShouldUseHttpServer>::new_from_argv(argv)
                .unwrap();
        let counter = register_int_counter!("comprehensive_test_total", "Number of happy").unwrap();
        counter.inc_by(111);

        let mut router = assembly.top.i.get_router();
        let req = http::request::Builder::new()
            .method("GET")
            .uri("http://unused/metrics")
            .body(axum::body::Body::empty())
            .unwrap();
        let resp = router.call(req).await.expect("success");
        assert_eq!(resp.status().as_u16(), 200);
        let body = axum::body::to_bytes(resp.into_body(), 10000)
            .await
            .expect("body");
        let body = std::str::from_utf8(&body).expect("text");
        assert!(body.contains("111"));
    }
}