Send fastn.app mountpoints to .wasm modules via x-fastn-app-mounts header

fastn-core/src/commands/serve.rs

@@ -587,9 +587,20 @@ async fn handle_endpoints(
     tracing::info!("url: {}", url);
 
     if url.starts_with("wasm+proxy://") {
+        let app_mounts = match config.app_mounts() {
+            Err(e) => return Some(Err(e)),
+            Ok(v) => v,
+        };
+
         return match config
             .ds
-            .handle_wasm(url, req, endpoint.mountpoint.to_string(), session_id)
+            .handle_wasm(
+                url,
+                req,
+                endpoint.mountpoint.to_string(),
+                app_mounts,
+                session_id,
+            )
             .await
         {
             Ok(r) => Some(Ok(to_response(r))),

fastn-core/src/config/mod.rs

@@ -1080,9 +1080,19 @@ impl Config {
         // fastn installed Apps
         config.package.apps = {
             let apps_temp: Vec<fastn_core::package::app::AppTemp> = fastn_doc.get("fastn#app")?;
-            let mut apps = vec![];
+            let mut apps: Vec<fastn_core::package::app::App> = vec![];
+
             for app in apps_temp.into_iter() {
-                apps.push(app.into_app(&config, session_id).await?);
+                let new_app_package = app.package.clone();
+                let new_app = app.into_app(&config, session_id).await?;
+
+                if let Some(found_app) = apps.iter().find(|a| a.package.name.eq(&new_app_package)) {
+                    return Err(fastn_core::Error::PackageError {
+                        message: format!("Mounting the same package twice is not yet allowed. Tried mounting `{}` which is aready mounted at `{}`", new_app_package, found_app.mount_point),
+                    });
+                }
+
+                apps.push(new_app);
             }
             apps
         };
@@ -1214,6 +1224,46 @@ impl Config {
                 .unwrap_or_else(|_| "sqlite:///fastn.sqlite".to_string()),
         }
     }
+
+    /// Get mounted apps (package's system name, mount point)
+    ///
+    /// ```ftd
+    /// ;; FASTN.ftd
+    /// -- fastn.app: Auth App
+    /// package: lets-auth.fifthtry.site
+    /// mount-point: /-/auth/
+    ///
+    /// -- fastn.app: Let's Talk App
+    /// package: lets-talk.fifthtry.site
+    /// mount-point: /talk/
+    /// ```
+    ///
+    /// Then the value will be a json string:
+    ///
+    /// ```json
+    /// { "lets-auth": "/-/auth/", "lets-talk": "/talk/" }
+    /// ```
+    ///
+    /// Keys `lets-auth` and `lets-talk` are `system` names of the associated packages.
+    pub fn app_mounts(&self) -> fastn_core::Result<std::collections::HashMap<String, String>> {
+        let mut mounts = std::collections::HashMap::new();
+
+        for a in &self.package.apps {
+            if a.package.system.is_none() {
+                return fastn_core::usage_error(format!(
+                    "Package {} used for app {} is not a system package",
+                    a.package.name, a.name
+                ));
+            }
+
+            mounts.insert(
+                a.package.system.clone().expect("already checked for None"),
+                a.mount_point.clone(),
+            );
+        }
+
+        Ok(mounts)
+    }
 }
 
 #[cfg(feature = "use-config-json")]

fastn-core/src/library2022/processor/http.rs

@@ -133,13 +133,19 @@ pub async fn process(
         let mountpoint = mountpoint.ok_or(ftd::interpreter::Error::OtherError(
             "Mountpoint not found!".to_string(),
         ))?;
+        let app_mounts = req_config
+            .config
+            .app_mounts()
+            .map_err(|e| ftd::interpreter::Error::OtherError(e.to_string()))?;
+
         match req_config
             .config
             .ds
             .handle_wasm(
                 url.to_string(),
                 &req_config.request,
                 mountpoint,
+                app_mounts,
                 // FIXME: we don't know how to handle unsaved wasm files. Maybe there is no way
                 // that an unsaved .wasm file can exist and this is fine.
                 &None,

fastn-ds/src/lib.rs

@@ -475,6 +475,7 @@ impl DocumentStore {
         wasm_url: String,
         req: &T,
         mountpoint: String,
+        app_mounts: std::collections::HashMap<String, String>,
         session_id: &Option<String>,
     ) -> Result<ft_sys_shared::Request, HttpError>
     where
@@ -486,10 +487,18 @@ impl DocumentStore {
                 .iter()
                 .map(|(k, v)| (k.as_str().to_string(), v.as_bytes().to_vec()))
                 .collect();
+
             headers.push((
                 fastn_utils::FASTN_MOUNTPOINT.to_string(),
                 mountpoint.into_bytes(),
             ));
+
+            let app_mounts = serde_json::to_string(&app_mounts).unwrap();
+            headers.push((
+                fastn_utils::FASTN_APP_MOUNTS.to_string(),
+                app_mounts.into_bytes(),
+            ));
+
             headers
         };
 

fastn-utils/src/lib.rs

@@ -55,4 +55,43 @@ pub fn row_to_json(r: &rusqlite::Row, count: usize) -> Result<Vec<serde_json::Va
     Ok(row)
 }
 
+/// Mountpoint is the path on which the wasm file is mounted.
+///
+/// If in FASTN.ftd, we have:
+///
+/// ```ftd
+/// -- import: fastn
+/// -- fastn.package: hello-world
+/// -- fastn.url-mappings:
+/// /foo/* -> wasm+proxy://hello-world.wasm/*
+/// ```
+///
+/// Then the `mountpoint` is `/foo/`.
 pub const FASTN_MOUNTPOINT: &str = "x-fastn-mountpoint";
+
+/// A json object that contains the mountpoints of `fastn.app`s
+///
+/// If in FASTN.ftd, we have:
+///
+/// ```ftd
+/// -- import: fastn
+/// -- fastn.package: hello-world
+///
+/// -- fastn.app: Auth App
+/// package: lets-auth.fifthtry.site
+/// mount-point: /-/auth/
+///
+/// -- fastn.app: Let's Talk App
+/// package: lets-talk.fifthtry.site
+/// mount-point: /talk/
+/// ```
+///
+/// Then the value will be a json string:
+///
+/// ```json
+/// { "lets-auth": "/-/auth/", "lets-talk": "/talk/" }
+/// ```
+///
+/// NOTE: `lets-auth.fifthtry.site` and `lets-talk.fifthtry.site` are required to be a system
+/// package. The names `lets-auth` and `lets-talk` are taken from their `system` field
+pub const FASTN_APP_MOUNTS: &str = "x-fastn-app-mounts";