feat: Add a Http Service integration with trace propagation (NATIVE-314)

Swatinem · Swatinem · commit 6a479ff2b87c · 2022-01-10T11:28:32.000+01:00
This creates a new sentry-tower feature that does trace propagation for
Http Services.
diff --git a/sentry-tower/Cargo.toml b/sentry-tower/Cargo.toml
@@ -11,9 +11,13 @@ Sentry integration for tower-based crates.
 """
 edition = "2018"
 
+[features]
+http = []
+
 [dependencies]
 tower-layer = "0.3"
 tower-service = "0.3"
+http = { version = "0.2.6", optional = true }
 sentry-core = { version = "0.23.0", path = "../sentry-core", default-features = false, features = ["client"] }
 
 [dev-dependencies]
diff --git a/sentry-tower/src/http.rs b/sentry-tower/src/http.rs
@@ -0,0 +1,104 @@
+use std::collections::BTreeMap;
+use std::future::Future;
+use std::pin::Pin;
+use std::task::{Context, Poll};
+
+use tower_layer::Layer;
+use tower_service::Service;
+
+#[derive(Clone)]
+pub struct SentryHttpLayer;
+
+#[derive(Clone)]
+pub struct SentryHttpService<S> {
+    service: S,
+}
+
+impl<S> Layer<S> for SentryHttpLayer {
+    type Service = SentryHttpService<S>;
+
+    fn layer(&self, service: S) -> Self::Service {
+        Self::Service { service }
+    }
+}
+
+pub struct SentryHttpFuture<F> {
+    transaction: Option<sentry_core::Transaction>,
+    future: F,
+}
+
+impl Future for SentryHttpFuture<F>
+where
+    F: Future,
+{
+    type Output = F::Output;
+
+    fn poll(self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<Self::Output> {
+        // https://doc.rust-lang.org/std/pin/index.html#pinning-is-structural-for-field
+        let future = unsafe { self.map_unchecked_mut(|s| &mut s.future) };
+        match future.poll(cx) {
+            Poll::Ready(res) => {
+                if let Some(transaction) = self.transaction.take() {
+                    transaction.finish();
+                }
+                Poll::Ready(res)
+            }
+            Poll::Pending => Poll::Pending,
+        }
+    }
+}
+
+impl<S, Body> Service<Request<Body>> for SentryHttpService<S>
+where
+    S: Service<Request<Body>>,
+{
+    type Response = S::Response;
+    type Error = S::Error;
+    type Future = SentryHttpFuture<S::Future>;
+
+    fn poll_ready(&mut self, cx: &mut Context<'_>) -> Poll<Result<(), Self::Error>> {
+        self.service.poll_ready(cx)
+    }
+
+    fn call(&mut self, request: Request<Body>) -> Self::Future {
+        let transaction = sentry::configure_scope(|scope| {
+            // https://develop.sentry.dev/sdk/event-payloads/request/
+            let mut ctx = BTreeMap::new();
+
+            // TODO: method, url, query_string
+
+            // headers
+            let mut headers = BTreeMap::new();
+            for (header, value) in request.headers() {
+                headers.insert(
+                    header.to_string(),
+                    value.to_str().unwrap_or("<Opaque header value>").into(),
+                );
+            }
+            ctx.insert("headers".into(), headers);
+
+            scope.set_context("request", sentry_core::protocol::Context::Other(ctx));
+
+            // TODO: maybe make transaction creation optional?
+            let transaction = if true {
+                let tx_ctx = sentry_core::TransactionContext::continue_from_headers(
+                    // TODO: whats the name here?
+                    "",
+                    "http",
+                    request.headers(),
+                );
+                Some(sentry_core::start_transaction(tx_ctx))
+            } else {
+                None
+            };
+
+            scope.set_span(transaction.clone());
+            transaction
+        });
+
+        SentryHttpFuture {
+            transaction,
+            future: self.service.call(request),
+        }
+    }
+}
diff --git a/sentry-tower/src/lib.rs b/sentry-tower/src/lib.rs
@@ -102,13 +102,17 @@
 #![doc(html_logo_url = "https://sentry-brand.storage.googleapis.com/sentry-glyph-black.png")]
 #![warn(missing_docs)]
 
-use sentry_core::{Hub, SentryFuture, SentryFutureExt};
 use std::marker::PhantomData;
 use std::sync::Arc;
 use std::task::{Context, Poll};
+
+use sentry_core::{Hub, SentryFuture, SentryFutureExt};
 use tower_layer::Layer;
 use tower_service::Service;
 
+#[cfg(feature = "http")]
+mod http;
+
 /// Provides a hub for each request
 pub trait HubProvider<H, Request>
 where
@@ -140,7 +144,7 @@ pub struct NewFromTopProvider;
 
 impl<Request> HubProvider<Arc<Hub>, Request> for NewFromTopProvider {
     fn hub(&self, _request: &Request) -> Arc<Hub> {
-        // The Clippy lint here is a falste positive, the suggestion to write
+        // The Clippy lint here is a false positive, the suggestion to write
         // `Hub::with(Hub::new_from_top)` does not compiles:
         //     143 |         Hub::with(Hub::new_from_top).into()
         //         |         ^^^^^^^^^ implementation of `std::ops::FnOnce` is not general enough
