salvo_otel/
metrics.rs

1use std::time::Instant;
2
3use opentelemetry::metrics::{Counter, Histogram};
4use opentelemetry::{KeyValue, global};
5use opentelemetry_semantic_conventions::trace;
6use salvo_core::http::ResBody;
7use salvo_core::prelude::*;
8
9/// Middleware for metrics with OpenTelemetry.
10pub struct Metrics {
11    request_count: Counter<u64>,
12    error_count: Counter<u64>,
13    duration: Histogram<f64>,
14}
15
16impl Default for Metrics {
17    fn default() -> Self {
18        Self::new()
19    }
20}
21
22impl Metrics {
23    /// Create `Metrics` middleware with `meter`.
24    pub fn new() -> Self {
25        let meter = global::meter("salvo");
26        Self {
27            request_count: meter
28                .u64_counter("salvo_request_count")
29                .with_description("total request count (since start of service)")
30                .build(),
31            error_count: meter
32                .u64_counter("salvo_error_count")
33                .with_description("failed request count (since start of service)")
34                .build(),
35            duration: meter
36                .f64_histogram("salvo_request_duration_ms")
37                .with_unit("milliseconds")
38                .with_description(
39                    "request duration histogram (in milliseconds, since start of service)",
40                )
41                .build(),
42        }
43    }
44}
45
46#[async_trait]
47impl Handler for Metrics {
48    async fn handle(
49        &self,
50        req: &mut Request,
51        depot: &mut Depot,
52        res: &mut Response,
53        ctrl: &mut FlowCtrl,
54    ) {
55        let mut labels = Vec::with_capacity(3);
56        labels.push(KeyValue::new(
57            trace::HTTP_REQUEST_METHOD,
58            req.method().to_string(),
59        ));
60        labels.push(KeyValue::new(trace::URL_FULL, req.uri().to_string()));
61
62        let s = Instant::now();
63        ctrl.call_next(req, depot, res).await;
64        let elapsed = s.elapsed();
65
66        let status = res.status_code.unwrap_or_else(|| {
67            tracing::info!("[otel::Metrics] Treat status_code=none as 200(OK).");
68            StatusCode::OK
69        });
70        labels.push(KeyValue::new(
71            trace::HTTP_RESPONSE_STATUS_CODE,
72            status.as_u16() as i64,
73        ));
74        if status.is_client_error() || status.is_server_error() {
75            self.error_count.add(1, &labels);
76            let msg = if let ResBody::Error(body) = &res.body {
77                body.to_string()
78            } else {
79                format!("ErrorCode: {}", status.as_u16())
80            };
81            labels.push(KeyValue::new(trace::EXCEPTION_MESSAGE, msg));
82        }
83
84        self.request_count.add(1, &labels);
85        self.duration
86            .record(elapsed.as_secs_f64() * 1000.0, &labels);
87    }
88}
salvo_otel/metrics.rs

salvo_otel/
metrics.rs
