add default_span_name helper function (#93)

reqwest-tracing/CHANGELOG.md

@@ -6,6 +6,11 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 ## [Unreleased]
 
+## [0.4.4] - 2023-05-15
+
+### Added
+- A new `default_span_name` method for use in custom span backends.
+
 ## [0.4.3] - 2023-05-15
 
 ### Fixed

reqwest-tracing/Cargo.toml

@@ -1,6 +1,6 @@
 [package]
 name = "reqwest-tracing"
-version = "0.4.3"
+version = "0.4.4"
 authors = ["Rodrigo Gryzinski <rodrigo.gryzinski@truelayer.com>"]
 edition = "2018"
 description = "Opentracing middleware for reqwest."

reqwest-tracing/src/lib.rs

@@ -96,9 +96,10 @@ mod reqwest_otel_span_builder;
 pub use middleware::TracingMiddleware;
 pub use reqwest_otel_span_builder::{
     default_on_request_end, default_on_request_failure, default_on_request_success,
-    DefaultSpanBackend, OtelName, OtelPathNames, ReqwestOtelSpanBackend, SpanBackendWithUrl,
+    default_span_name, DefaultSpanBackend, OtelName, OtelPathNames, ReqwestOtelSpanBackend,
-    ERROR_CAUSE_CHAIN, ERROR_MESSAGE, HTTP_HOST, HTTP_METHOD, HTTP_SCHEME, HTTP_STATUS_CODE,
+    SpanBackendWithUrl, ERROR_CAUSE_CHAIN, ERROR_MESSAGE, HTTP_HOST, HTTP_METHOD, HTTP_SCHEME,
-    HTTP_URL, HTTP_USER_AGENT, NET_HOST_PORT, OTEL_KIND, OTEL_NAME, OTEL_STATUS_CODE,
+    HTTP_STATUS_CODE, HTTP_URL, HTTP_USER_AGENT, NET_HOST_PORT, OTEL_KIND, OTEL_NAME,
+    OTEL_STATUS_CODE,
 };
 
 #[doc(hidden)]

reqwest-tracing/src/reqwest_otel_span_builder.rs

@@ -84,6 +84,27 @@ pub fn default_on_request_failure(span: &Span, e: &Error) {
     }
 }
 
+/// Determine the name of the span that should be associated with this request.
+///
+/// This tries to be PII safe by default, not including any path information unless
+/// specifically opted in using either [`OtelName`] or [`OtelPathNames`]
+#[inline]
+pub fn default_span_name<'a>(req: &'a Request, ext: &'a Extensions) -> Cow<'a, str> {
+    if let Some(name) = ext.get::<OtelName>() {
+        Cow::Borrowed(name.0.as_ref())
+    } else if let Some(path_names) = ext.get::<OtelPathNames>() {
+        path_names
+            .find(req.url().path())
+            .map(|path| Cow::Owned(format!("{} {}", req.method(), path)))
+            .unwrap_or_else(|| {
+                warn!("no OTEL path name found");
+                Cow::Owned(format!("{} UNKNOWN", req.method().as_str()))
+            })
+    } else {
+        Cow::Borrowed(req.method().as_str())
+    }
+}
+
 /// The default [`ReqwestOtelSpanBackend`] for [`TracingMiddleware`]. Note that it doesn't include
 /// the `http.url` field in spans, you can use [`SpanBackendWithUrl`] to add it.
 ///
@@ -92,20 +113,7 @@ pub struct DefaultSpanBackend;
 
 impl ReqwestOtelSpanBackend for DefaultSpanBackend {
     fn on_request_start(req: &Request, ext: &mut Extensions) -> Span {
-        let name = if let Some(name) = ext.get::<OtelName>() {
+        let name = default_span_name(req, ext);
-            Cow::Borrowed(name.0.as_ref())
-        } else if let Some(path_names) = ext.get::<OtelPathNames>() {
-            path_names
-                .find(req.url().path())
-                .map(|path| Cow::Owned(format!("{} {}", req.method(), path)))
-                .unwrap_or_else(|| {
-                    warn!("no OTEL path name found");
-                    Cow::Owned(format!("{} UNKNOWN", req.method().as_str()))
-                })
-        } else {
-            Cow::Borrowed(req.method().as_str())
-        };
-
         reqwest_otel_span!(name = name, req)
     }
 
@@ -126,20 +134,7 @@ pub struct SpanBackendWithUrl;
 
 impl ReqwestOtelSpanBackend for SpanBackendWithUrl {
     fn on_request_start(req: &Request, ext: &mut Extensions) -> Span {
-        let name = if let Some(name) = ext.get::<OtelName>() {
+        let name = default_span_name(req, ext);
-            Cow::Borrowed(name.0.as_ref())
-        } else if let Some(path_names) = ext.get::<OtelPathNames>() {
-            path_names
-                .find(req.url().path())
-                .map(|path| Cow::Owned(format!("{} {}", req.method(), path)))
-                .unwrap_or_else(|| {
-                    warn!("no OTEL path name found");
-                    Cow::Owned(format!("{} UNKNOWN", req.method().as_str()))
-                })
-        } else {
-            Cow::Borrowed(req.method().as_str())
-        };
-
         reqwest_otel_span!(name = name, req, http.url = %remove_credentials(req.url()))
     }