allow outbound calls to components in same spin app

+ use special value `self` in allowed_http_hosts
to allow components in the same spin app to make outbound
http requests to each other
+ make requests with relative routes in app once self is set
+ update example for rust outbound http to demonstrate capability
+ adds e2e
+ resolves spinframework#957
+ resolves spinframework#1533

Signed-off-by: Michelle Dhanani <michelle@fermyon.com>

crates/outbound-http/src/allowed_http_hosts.rs

@@ -26,6 +26,13 @@ impl AllowedHttpHosts {
             Self::AllowSpecific(hosts) => hosts.iter().any(|h| h.allow(url)),
         }
     }
+
+    pub fn includes(&self, host: AllowedHttpHost) -> bool {
+        match self {
+            Self::AllowAll => true,
+            Self::AllowSpecific(hosts) => hosts.contains(&host),
+        }
+    }
 }
 
 /// An HTTP host allow-list entry.
@@ -214,6 +221,14 @@ mod test {
         );
     }
 
+    #[test]
+    fn test_allowed_hosts_accepts_self() {
+        assert_eq!(
+            AllowedHttpHost::host("self"),
+            parse_allowed_http_host("self").unwrap()
+        );
+    }
+
     #[test]
     fn test_allowed_hosts_accepts_localhost_addresses() {
         assert_eq!(
@@ -303,4 +318,13 @@ mod test {
         assert!(!allowed.allow(&Url::parse("http://example.com/").unwrap()));
         assert!(!allowed.allow(&Url::parse("http://google.com/").unwrap()));
     }
+
+    #[test]
+    fn test_allowed_hosts_includes() {
+        let allowed =
+            parse_allowed_http_hosts(&to_vec_owned(&["self", "http://example.com:8383"])).unwrap();
+        assert!(allowed.includes(AllowedHttpHost::host("self")));
+        assert!(allowed.includes(AllowedHttpHost::host_and_port("example.com", 8383)));
+        assert!(!allowed.includes(AllowedHttpHost::host("google.com")));
+    }
 }

crates/outbound-http/src/lib.rs

@@ -11,7 +11,7 @@ use spin_world::{
     http_types::{Headers, HttpError, Method, Request, Response},
 };
 
-use allowed_http_hosts::AllowedHttpHosts;
+use allowed_http_hosts::{AllowedHttpHost, AllowedHttpHosts};
 pub use host_component::OutboundHttpComponent;
 
 pub const ALLOWED_HTTP_HOSTS_KEY: MetadataKey<Vec<String>> = MetadataKey::new("allowed_http_hosts");
@@ -21,15 +21,27 @@ pub const ALLOWED_HTTP_HOSTS_KEY: MetadataKey<Vec<String>> = MetadataKey::new("a
 pub struct OutboundHttp {
     /// List of hosts guest modules are allowed to make requests to.
     pub allowed_hosts: AllowedHttpHosts,
+    /// During an incoming HTTP request, origin is set to the host of that incoming HTTP request.
+    /// This is used to direct outbound requests to the same host when allowed.
+    pub origin: String,
     client: Option<Client>,
 }
 
 impl OutboundHttp {
     /// Check if guest module is allowed to send request to URL, based on the list of
-    /// allowed hosts defined by the runtime. If the list of allowed hosts contains
+    /// allowed hosts defined by the runtime. If the url passed in is a relative path,
+    /// only allow if allowed_hosts contains `self`. If the list of allowed hosts contains
     /// `insecure:allow-all`, then all hosts are allowed.
     /// If `None` is passed, the guest module is not allowed to send the request.
-    fn is_allowed(&self, url: &str) -> Result<bool, HttpError> {
+    fn is_allowed(&mut self, url: &str) -> Result<bool, HttpError> {
+        if url.starts_with('/') {
+            if self.allowed_hosts.includes(AllowedHttpHost::host("self")) {
+                return Ok(true);
+            } else {
+                return Ok(false);
+            }
+        }
+
         let url = Url::parse(url).map_err(|_| HttpError::InvalidUrl)?;
         Ok(self.allowed_hosts.allow(&url))
     }
@@ -49,7 +61,14 @@ impl outbound_http::Host for OutboundHttp {
             }
 
             let method = method_from(req.method);
-            let url = Url::parse(&req.uri).map_err(|_| HttpError::InvalidUrl)?;
+
+            let req_url: Url = if req.uri.starts_with('/') {
+                Url::parse(&format!("{}{}", self.origin, req.uri))
+                    .map_err(|_| HttpError::InvalidUrl)?
+            } else {
+                Url::parse(&req.uri).map_err(|_| HttpError::InvalidUrl)?
+            };
+
             let headers = request_headers(req.headers).map_err(|_| HttpError::RuntimeError)?;
             let body = req.body.unwrap_or_default().to_vec();
 
@@ -62,7 +81,7 @@ impl outbound_http::Host for OutboundHttp {
             let client = self.client.get_or_insert_with(Default::default);
 
             let resp = client
-                .request(method, url)
+                .request(method, req_url)
                 .headers(headers)
                 .body(body)
                 .send()

crates/trigger-http/Cargo.toml

@@ -16,6 +16,7 @@ futures-util = "0.3.8"
 http = "0.2"
 hyper = { version = "0.14", features = ["full"] }
 indexmap = "1"
+outbound-http = { path = "../outbound-http" }
 percent-encoding = "2"
 rustls-pemfile = "0.3.0"
 serde = { version = "1.0", features = ["derive"] }

crates/trigger-http/src/spin.rs

@@ -27,11 +27,27 @@ impl HttpExecutor for SpinHttpExecutor {
             component_id
         );
 
-        let (instance, store) = engine.prepare_instance(component_id).await?;
+        let (instance, mut store) = engine.prepare_instance(component_id).await?;
         let EitherInstance::Component(instance) = instance else {
             unreachable!()
         };
 
+        if let Some(authority) = req.uri().authority() {
+            if let Some(scheme) = req.uri().scheme_str() {
+                if let Some(outbound_http_handle) = engine
+                .engine
+                .find_host_component_handle::<std::sync::Arc<outbound_http::OutboundHttpComponent>>(
+                )
+            {
+                let outbound_http_data = store
+                    .host_components_data()
+                    .get_or_insert(outbound_http_handle);
+
+                outbound_http_data.origin = format!("{}://{}", scheme, authority);
+            }
+            }
+        }
+
         let resp = Self::execute_impl(store, instance, base, raw_route, req, client_addr)
             .await
             .map_err(contextualise_err)?;