tower_http/trace/
on_response.rs

1use super::{Latency, DEFAULT_MESSAGE_LEVEL};
2use crate::LatencyUnit;
3use http::Response;
4use std::time::Duration;
5use tracing::Level;
6use tracing::Span;
7
8/// Trait used to tell [`Trace`] what to do when a response has been produced.
9///
10/// See the [module docs](../trace/index.html#on_response) for details on exactly when the
11/// `on_response` callback is called.
12///
13/// [`Trace`]: super::Trace
14pub trait OnResponse<B> {
15    /// Do the thing.
16    ///
17    /// `latency` is the duration since the request was received.
18    ///
19    /// `span` is the `tracing` [`Span`], corresponding to this request, produced by the closure
20    /// passed to [`TraceLayer::make_span_with`]. It can be used to [record field values][record]
21    /// that weren't known when the span was created.
22    ///
23    /// [`Span`]: https://docs.rs/tracing/latest/tracing/span/index.html
24    /// [record]: https://docs.rs/tracing/latest/tracing/span/struct.Span.html#method.record
25    /// [`TraceLayer::make_span_with`]: crate::trace::TraceLayer::make_span_with
26    fn on_response(self, response: &Response<B>, latency: Duration, span: &Span);
27}
28
29impl<B> OnResponse<B> for () {
30    #[inline]
31    fn on_response(self, _: &Response<B>, _: Duration, _: &Span) {}
32}
33
34impl<B, F> OnResponse<B> for F
35where
36    F: FnOnce(&Response<B>, Duration, &Span),
37{
38    fn on_response(self, response: &Response<B>, latency: Duration, span: &Span) {
39        self(response, latency, span)
40    }
41}
42
43/// The default [`OnResponse`] implementation used by [`Trace`].
44///
45/// [`Trace`]: super::Trace
46#[derive(Clone, Debug)]
47pub struct DefaultOnResponse {
48    level: Level,
49    latency_unit: LatencyUnit,
50    include_headers: bool,
51}
52
53impl Default for DefaultOnResponse {
54    fn default() -> Self {
55        Self {
56            level: DEFAULT_MESSAGE_LEVEL,
57            latency_unit: LatencyUnit::Millis,
58            include_headers: false,
59        }
60    }
61}
62
63impl DefaultOnResponse {
64    /// Create a new `DefaultOnResponse`.
65    pub fn new() -> Self {
66        Self::default()
67    }
68
69    /// Set the [`Level`] used for [tracing events].
70    ///
71    /// Please note that while this will set the level for the tracing events
72    /// themselves, it might cause them to lack expected information, like
73    /// request method or path. You can address this using
74    /// [`DefaultMakeSpan::level`].
75    ///
76    /// Defaults to [`Level::DEBUG`].
77    ///
78    /// [tracing events]: https://docs.rs/tracing/latest/tracing/#events
79    /// [`DefaultMakeSpan::level`]: crate::trace::DefaultMakeSpan::level
80    pub fn level(mut self, level: Level) -> Self {
81        self.level = level;
82        self
83    }
84
85    /// Set the [`LatencyUnit`] latencies will be reported in.
86    ///
87    /// Defaults to [`LatencyUnit::Millis`].
88    pub fn latency_unit(mut self, latency_unit: LatencyUnit) -> Self {
89        self.latency_unit = latency_unit;
90        self
91    }
92
93    /// Include response headers on the [`Event`].
94    ///
95    /// By default headers are not included.
96    ///
97    /// [`Event`]: tracing::Event
98    pub fn include_headers(mut self, include_headers: bool) -> Self {
99        self.include_headers = include_headers;
100        self
101    }
102}
103
104impl<B> OnResponse<B> for DefaultOnResponse {
105    fn on_response(self, response: &Response<B>, latency: Duration, span: &Span) {
106        let latency = Latency {
107            unit: self.latency_unit,
108            duration: latency,
109        };
110        let response_headers = self
111            .include_headers
112            .then(|| tracing::field::debug(response.headers()));
113
114        event_dynamic_lvl!(
115            parent: span,
116            self.level,
117            %latency,
118            status = status(response),
119            response_headers,
120            "finished processing request"
121        );
122    }
123}
124
125fn status<B>(res: &Response<B>) -> Option<i32> {
126    use crate::classify::grpc_errors_as_failures::ParsedGrpcStatus;
127
128    // gRPC-over-HTTP2 uses the "application/grpc[+format]" content type, and gRPC-Web uses
129    // "application/grpc-web[+format]" or "application/grpc-web-text[+format]", where "format" is
130    // the message format, e.g. +proto, +json.
131    //
132    // So, valid grpc content types include (but are not limited to):
133    //  - application/grpc
134    //  - application/grpc+proto
135    //  - application/grpc-web+proto
136    //  - application/grpc-web-text+proto
137    //
138    // For simplicity, we simply check that the content type starts with "application/grpc".
139    let is_grpc = res
140        .headers()
141        .get(http::header::CONTENT_TYPE)
142        .map_or(false, |value| {
143            value.as_bytes().starts_with("application/grpc".as_bytes())
144        });
145
146    if is_grpc {
147        match crate::classify::grpc_errors_as_failures::classify_grpc_metadata(
148            res.headers(),
149            crate::classify::GrpcCode::Ok.into_bitmask(),
150        ) {
151            ParsedGrpcStatus::Success | ParsedGrpcStatus::HeaderNotGrpcCode => Some(0),
152            ParsedGrpcStatus::NonSuccess(status) => Some(status.code_raw()),
153            // if `grpc-status` is missing then its a streaming response and there is no status
154            // _yet_, so its neither success nor error
155            ParsedGrpcStatus::GrpcStatusHeaderMissing => None,
156        }
157    } else {
158        Some(res.status().as_u16().into())
159    }
160}
tower_http/trace/on_response.rs

tower_http/trace/
on_response.rs
