Improve code and docs for serving Ember.js HTML

Author: jtgeibel

src/middleware.rs

@@ -6,7 +6,7 @@ mod prelude {
 use self::app::AppMiddleware;
 use self::current_user::CaptureUserIdFromCookie;
 use self::debug::*;
-use self::ember_index_rewrite::EmberIndexRewrite;
+use self::ember_html::EmberHtml;
 use self::head::Head;
 use self::log_connection_pool_status::LogConnectionPoolStatus;
 use self::static_or_continue::StaticOrContinue;
@@ -15,7 +15,7 @@ pub mod app;
 mod block_traffic;
 pub mod current_user;
 mod debug;
-mod ember_index_rewrite;
+mod ember_html;
 mod ensure_well_formed_500;
 mod head;
 mod log_connection_pool_status;
@@ -72,13 +72,13 @@ pub fn build_middleware(app: Arc<App>, endpoints: R404) -> MiddlewareBuilder {
     // Parse and save the user_id from the session cookie as part of the authentication logic
     m.add(CaptureUserIdFromCookie);
 
+    // Note: The following `m.around()` middleware is run from bottom to top
+
     // Serve the static files in the *dist* directory, which are the frontend assets.
     // Not needed for the backend tests.
     if env != Env::Test {
+        m.around(EmberHtml::new("dist"));
         m.around(StaticOrContinue::new("dist"));
-        m.around(EmberIndexRewrite::default());
-        m.around(StaticOrContinue::new("dist"));
-        // Note: around middleware is run from bottom to top, so the rewrite occurs first
     }
 
     m.around(Head::default());

src/middleware/ember_index_rewrite.rs renamed to src/middleware/ember_html.rs

@@ -1,48 +1,56 @@
-//! Rewrite the request path to "index.html" if the path doesn't start
-//! with "/api" and the Accept header contains "html".
+//! Serve the Ember.js frontend HTML
+//!
+//! Paths intended for the inner `api_handler` are passed along to the remaining middleware layers
+//! as normal. Requests not intended for the backend will be served HTML to boot the Ember.js
+//! frontend. During local development, if so configured, these requests will instead be proxied to
+//! Ember FastBoot (`node ./fastboot.js`).
+//!
+//! For now, there is an additional check to see if the `Accept` header contains "html". This is
+//! likely to be removed in the future.
 
 use super::prelude::*;
 use std::fmt::Write;
 
 use crate::util::{errors::NotFound, AppResponse, Error, RequestProxy};
 
 use conduit::{Body, HandlerResult};
+use conduit_static::Static;
 use reqwest::blocking::Client;
 
-// Can't derive debug because of Handler and Static.
-#[allow(missing_debug_implementations)]
-pub struct EmberIndexRewrite {
-    handler: Option<Box<dyn Handler>>,
+pub(super) struct EmberHtml {
+    api_handler: Option<Box<dyn Handler>>,
+    static_handler: Static,
     fastboot_client: Option<Client>,
 }
 
-impl Default for EmberIndexRewrite {
-    fn default() -> EmberIndexRewrite {
+impl EmberHtml {
+    pub fn new(path: &str) -> Self {
         let fastboot_client = match dotenv::var("USE_FASTBOOT") {
             Ok(val) if val == "staging-experimental" => Some(Client::new()),
             _ => None,
         };
 
-        EmberIndexRewrite {
-            handler: None,
+        Self {
+            api_handler: None,
+            static_handler: Static::new(path),
             fastboot_client,
         }
     }
 }
 
-impl AroundMiddleware for EmberIndexRewrite {
+impl AroundMiddleware for EmberHtml {
     fn with_handler(&mut self, handler: Box<dyn Handler>) {
-        self.handler = Some(handler);
+        self.api_handler = Some(handler);
     }
 }
 
-impl Handler for EmberIndexRewrite {
+impl Handler for EmberHtml {
     fn call(&self, req: &mut dyn RequestExt) -> HandlerResult {
-        let handler = self.handler.as_ref().unwrap();
+        let api_handler = self.api_handler.as_ref().unwrap();
 
         // The "/git/" prefix is only used in development (when within a docker container)
         if req.path().starts_with("/api/") || req.path().starts_with("/git/") {
-            handler.call(req)
+            api_handler.call(req)
         } else {
             if let Some(client) = &self.fastboot_client {
                 // During local fastboot development, forward requests to the local fastboot server.
@@ -58,7 +66,8 @@ impl Handler for EmberIndexRewrite {
                 .any(|val| val.to_str().unwrap_or_default().contains("html"))
             {
                 // Serve static Ember page to bootstrap the frontend
-                handler.call(&mut RequestProxy::rewrite_path(req, "/index.html"))
+                self.static_handler
+                    .call(&mut RequestProxy::rewrite_path(req, "/index.html"))
             } else {
                 // Return a 404 to crawlers that don't send `Accept: text/hml`.
                 // This is to preserve legacy behavior and will likely change.