Struct OtelLayer 

pub struct OtelLayer;

Middleware that creates an HTTP server span for each request.

• Reads W3C traceparent from the request to continue an existing trace.
• Creates a new trace when no traceparent is present.
• Stores the active span in thread-local storage so downstream middleware (e.g. crate::proxy::ReverseProxy) can propagate it.
• Records the span on the way out with http.method, http.target, and http.status_code attributes.

Requires setup or setup_from_env to be called at startup. Without initialisation the layer is a no-op passthrough.

Trait Implementations

impl Middleware for OtelLayer

fn handle( &self, request: &Request, connection: &ConnectionInfo, next: &dyn Application, ) -> Result<Response, String>

fn runs_inline(&self, _request: &Request, _connection: &ConnectionInfo) -> bool

true when this layer’s own work for request never blocks (in-memory state, atomics, short mutexes) — see Application::runs_inline. A WithMiddleware stack runs inline only if every layer and the inner application agree. Default false.

fn is_passthrough( &self, _request: &Request, _connection: &ConnectionInfo, ) -> bool

true when handle would do nothing for request but call next (e.g. a rate limit that isn’t configured). A WithMiddleware stack offers the inner application’s execute_async only if every layer passes the request through. Default false.

fn accepts_streamed_body( &self, _request: &Request, _connection: &ConnectionInfo, ) -> bool

true when this layer never reads request.body, so the inner application may receive it as a stream (Application::streams_body). A layer that inspects the body (CSRF tokens in a form, request signatures, rewriting) must keep the default false: it would see an empty body.

fn answers_streamed_body( &self, _request: &Request, _connection: &ConnectionInfo, ) -> bool

true when this layer answers request itself — it doesn’t call next — and reads its body as a stream (a proxy forwarding it as it arrives). The body is then streamed whatever the layers after it and the application would say. Requires accepts_streamed_body. Since 18.3.0.