Expose the raw http path coming from the lambda event. (aws#453)

calavera · web-flow · commit 3e378187896d · 2022-03-23T08:02:56.000-07:00
The API GW url includes th API GW stage information, so
it's not easy to know what's the raw http path coming into
the event.

With this change, we expose the raw http path in a general
way, so people that need to know the exact raw path have
a common interface, regardless of where the event comes from.

Signed-off-by: David Calavera &lt;david.calavera@gmail.com&gt;
diff --git a/lambda-http/examples/hello-raw-http-path.rs b/lambda-http/examples/hello-raw-http-path.rs
@@ -0,0 +1,13 @@
+use lambda_http::{service_fn, Error, IntoResponse, Request, RequestExt};
+
+#[tokio::main]
+async fn main() -> Result<(), Error> {
+    lambda_http::run(service_fn(func)).await?;
+    Ok(())
+}
+
+async fn func(event: Request) -> Result<impl IntoResponse, Error> {
+    let res = format!("The raw path for this request is: {}", event.raw_http_path()).into_response();
+
+    Ok(res)
+}
diff --git a/lambda-http/src/ext.rs b/lambda-http/src/ext.rs
@@ -20,6 +20,9 @@ pub(crate) struct PathParameters(pub(crate) QueryMap);
 /// These will always be empty for ALB requests
 pub(crate) struct StageVariables(pub(crate) QueryMap);
 
+/// ALB/API gateway raw http path without any stage information
+pub(crate) struct RawHttpPath(pub(crate) String);
+
 /// Request payload deserialization errors
 ///
 /// Returned by [`RequestExt#payload()`](trait.RequestExt.html#tymethod.payload)
@@ -104,6 +107,12 @@ impl Error for PayloadError {
 /// }
 /// ```
 pub trait RequestExt {
+    /// Return the raw http path for a request without any stage information.
+    fn raw_http_path(&self) -> String;
+
+    /// Configures instance with the raw http path.
+    fn with_raw_http_path(self, path: &str) -> Self;
+
     /// Return pre-parsed http query string parameters, parameters
     /// provided after the `?` portion of a url,
     /// associated with the API gateway request.
@@ -177,6 +186,19 @@ pub trait RequestExt {
 }
 
 impl RequestExt for http::Request<Body> {
+    fn raw_http_path(&self) -> String {
+        self.extensions()
+            .get::<RawHttpPath>()
+            .map(|ext| ext.0.clone())
+            .unwrap_or_default()
+    }
+
+    fn with_raw_http_path(self, path: &str) -> Self {
+        let mut s = self;
+        s.extensions_mut().insert(RawHttpPath(path.into()));
+        s
+    }
+
     fn query_string_parameters(&self) -> QueryMap {
         self.extensions()
             .get::<QueryStringParameters>()
@@ -401,4 +423,10 @@ mod tests {
         let payload: Option<Payload> = request.payload().unwrap_or_default();
         assert_eq!(payload, None);
     }
+
+    #[test]
+    fn requests_can_mock_raw_http_path_ext() {
+        let request = Request::default().with_raw_http_path("/raw-path");
+        assert_eq!("/raw-path", request.raw_http_path().as_str());
+    }
 }
diff --git a/lambda-http/src/request.rs b/lambda-http/src/request.rs
@@ -3,7 +3,7 @@
 //! Typically these are exposed via the `request_context`
 //! request extension method provided by [lambda_http::RequestExt](../trait.RequestExt.html)
 //!
-use crate::ext::{PathParameters, QueryStringParameters, StageVariables};
+use crate::ext::{PathParameters, QueryStringParameters, RawHttpPath, StageVariables};
 use aws_lambda_events::alb::{AlbTargetGroupRequest, AlbTargetGroupRequestContext};
 use aws_lambda_events::apigw::{
     ApiGatewayProxyRequest, ApiGatewayProxyRequestContext, ApiGatewayV2httpRequest, ApiGatewayV2httpRequestContext,
@@ -61,6 +61,8 @@ pub enum RequestOrigin {
 
 fn into_api_gateway_v2_request(ag: ApiGatewayV2httpRequest) -> http::Request<Body> {
     let http_method = ag.request_context.http.method.clone();
+    let raw_path = ag.raw_path.unwrap_or_default();
+
     let builder = http::Request::builder()
         .uri({
             let scheme = ag
@@ -75,7 +77,7 @@ fn into_api_gateway_v2_request(ag: ApiGatewayV2httpRequest) -> http::Request<Bod
                 .or(ag.request_context.domain_name.as_deref())
                 .unwrap_or_default();
 
-            let path = apigw_path_with_stage(&ag.request_context.stage, ag.raw_path.as_deref().unwrap_or_default());
+            let path = apigw_path_with_stage(&ag.request_context.stage, &raw_path);
             let mut url = format!("{}://{}{}", scheme, host, path);
 
             if let Some(query) = ag.raw_query_string {
@@ -84,6 +86,7 @@ fn into_api_gateway_v2_request(ag: ApiGatewayV2httpRequest) -> http::Request<Bod
             }
             url
         })
+        .extension(RawHttpPath(raw_path))
         .extension(QueryStringParameters(ag.query_string_parameters))
         .extension(PathParameters(QueryMap::from(ag.path_parameters)))
         .extension(StageVariables(QueryMap::from(ag.stage_variables)))
@@ -115,10 +118,12 @@ fn into_api_gateway_v2_request(ag: ApiGatewayV2httpRequest) -> http::Request<Bod
 
 fn into_proxy_request(ag: ApiGatewayProxyRequest) -> http::Request<Body> {
     let http_method = ag.http_method;
+    let raw_path = ag.path.unwrap_or_default();
+
     let builder = http::Request::builder()
         .uri({
             let host = ag.headers.get(http::header::HOST).and_then(|s| s.to_str().ok());
-            let path = apigw_path_with_stage(&ag.request_context.stage, &ag.path.unwrap_or_default());
+            let path = apigw_path_with_stage(&ag.request_context.stage, &raw_path);
 
             let mut url = match host {
                 None => path,
@@ -141,6 +146,7 @@ fn into_proxy_request(ag: ApiGatewayProxyRequest) -> http::Request<Body> {
             }
             url
         })
+        .extension(RawHttpPath(raw_path))
         // multi-valued query string parameters are always a super
         // set of singly valued query string parameters,
         // when present, multi-valued query string parameters are preferred
@@ -178,6 +184,8 @@ fn into_proxy_request(ag: ApiGatewayProxyRequest) -> http::Request<Body> {
 
 fn into_alb_request(alb: AlbTargetGroupRequest) -> http::Request<Body> {
     let http_method = alb.http_method;
+    let raw_path = alb.path.unwrap_or_default();
+
     let builder = http::Request::builder()
         .uri({
             let scheme = alb
@@ -191,7 +199,7 @@ fn into_alb_request(alb: AlbTargetGroupRequest) -> http::Request<Body> {
                 .and_then(|s| s.to_str().ok())
                 .unwrap_or_default();
 
-            let mut url = format!("{}://{}{}", scheme, host, alb.path.unwrap_or_default());
+            let mut url = format!("{}://{}{}", scheme, host, &raw_path);
             if !alb.multi_value_query_string_parameters.is_empty() {
                 url.push('?');
                 url.push_str(&alb.multi_value_query_string_parameters.to_query_string());
@@ -202,6 +210,7 @@ fn into_alb_request(alb: AlbTargetGroupRequest) -> http::Request<Body> {
 
             url
         })
+        .extension(RawHttpPath(raw_path))
         // multi valued query string parameters are always a super
         // set of singly valued query string parameters,
         // when present, multi-valued query string parameters are preferred
