impl: fallback behavior

.github/workflows/e2e-cli-master.yaml

@@ -28,7 +28,7 @@ jobs:
           cargo install --path .
         working-directory: ./loco-cli
       - run: |
-          loco new -n saas -t saas --db sqlite --bg async --assets none
+          loco new -n saas -t saas --db sqlite --bg async --assets serverside
         env:
           ALLOW_IN_GIT_REPO: true
       - run: |

docs-site/content/docs/the-app/controller.md

@@ -299,6 +299,43 @@ async fn current(
 }
 ```
 
+## Fallback
+
+When choosing the SaaS starter (or any starter that is not API-first), you get a default fallback behavior with the _Loco welcome screen_. This is a development-only mode where a `404` request shows you a nice and friendly page that tells you what happened and what to do next.
+
+
+You can disable or customize this behavior in your `development.yaml` file. You can set a few options:
+
+
+```yaml
+# the default pre-baked welcome screen
+fallback:
+    enable: true
+```
+
+```yaml
+# a different predefined 404 page
+fallback:
+    enable: true
+    file: assets/404.html
+```
+
+```yaml
+# a message, and customizing the status code to return 200 instead of 404
+fallback:
+    enable: true
+    code: 200
+    not_found: cannot find this resource
+```
+
+For production, it's recommended to disable this.
+
+```yaml
+# disable. you can also remove the `fallback` section entirely to disable
+fallback:
+    enable: false
+```
+
 ## Remote IP
 
 When your app is under a proxy or a load balancer (e.g. Nginx, ELB, etc.), it does not face the internet directly, which is why if you want to find out the connecting client IP, you'll get a socket which indicates an IP that is actually your load balancer instead.

loco-cli/tests/cmd/starters/generate-starters.trycmd

@@ -4,6 +4,8 @@ $ ALLOW_IN_GIT_REPO="" LOCO_APP_NAME="test_saas_template" LOCO_FOLDER_NAME=saas_
 🚂 Loco app generated successfully in:
 [CWD]/test_saas_template
 
+- database: You've selected `postgres` as your DB provider (you should have a postgres instance to connect to)
+
 ```
 
 ```console
@@ -12,6 +14,8 @@ $ ALLOW_IN_GIT_REPO="true" LOCO_APP_NAME="test_rest_api_template" LOCO_FOLDER_NA
 🚂 Loco app generated successfully in:
 [CWD]/test_rest_api_template
 
+
+
 ```
 
 ```console
@@ -20,4 +24,6 @@ $ ALLOW_IN_GIT_REPO="true" LOCO_APP_NAME="test_lightweight_template" LOCO_FOLDER
 🚂 Loco app generated successfully in:
 [CWD]/test_lightweight_template
 
+
+
 ```

src/config.rs

@@ -391,8 +391,25 @@ pub struct Middlewares {
     pub secure_headers: Option<SecureHeadersConfig>,
     /// Calculates a remote IP based on `X-Forwarded-For` when behind a proxy
     pub remote_ip: Option<RemoteIPConfig>,
+    /// Configure fallback behavior when hitting a missing URL
+    pub fallback: Option<FallbackConfig>,
 }
 
+#[derive(Debug, Clone, Deserialize, Serialize)]
+pub struct FallbackConfig {
+    /// By default when enabled, returns a prebaked 404 not found page optimized
+    /// for development. For production set something else (see fields below)
+    pub enable: bool,
+    /// For the unlikely reason to return something different than `404`, you
+    /// can set it here
+    pub code: Option<u16>,
+    /// Returns content from a file pointed to by this field with a `404` status
+    /// code.
+    pub file: Option<String>,
+    /// Returns a "404 not found" with a single message string. This sets the
+    /// message.
+    pub not_found: Option<String>,
+}
 /// Static asset middleware configuration
 #[derive(Debug, Clone, Deserialize, Serialize)]
 pub struct StaticAssetsMiddleware {

src/controller/app_routes.rs

@@ -4,7 +4,12 @@
 
 use std::{fmt, path::PathBuf, time::Duration};
 
-use axum::{http, response::IntoResponse, Router as AXRouter};
+use axum::{
+    http,
+    response::{Html, IntoResponse},
+    Router as AXRouter,
+};
+use hyper::StatusCode;
 use lazy_static::lazy_static;
 use regex::Regex;
 use tower_http::{
@@ -25,14 +30,14 @@ use super::{
 };
 use crate::{
     app::AppContext,
-    config,
+    config::{self, FallbackConfig},
     controller::middleware::{
         etag::EtagLayer,
         remote_ip::RemoteIPLayer,
         request_id::{request_id_middleware, LocoRequestId},
     },
     environment::Environment,
-    errors, Result,
+    errors, Error, Result,
 };
 
 lazy_static! {
@@ -297,6 +302,12 @@ impl AppRoutes {
             tracing::info!("[Middleware] +secure headers");
         }
 
+        if let Some(fallback) = &ctx.config.server.middlewares.fallback {
+            if fallback.enable {
+                app = Self::add_fallback(app, fallback)?;
+            }
+        }
+
         app = Self::add_powered_by_header(app, &ctx.config.server);
 
         app = Self::add_request_id_middleware(app);
@@ -305,6 +316,36 @@ impl AppRoutes {
         Ok(router)
     }
 
+    fn add_fallback(
+        app: AXRouter<AppContext>,
+        fallback: &FallbackConfig,
+    ) -> Result<AXRouter<AppContext>> {
+        let app = if let Some(path) = &fallback.file {
+            app.fallback_service(ServeFile::new(path))
+        } else if let Some(not_found) = &fallback.not_found {
+            let not_found = not_found.to_string();
+            let code = fallback
+                .code
+                .map(StatusCode::from_u16)
+                .transpose()
+                .map_err(|e| Error::Message(format!("{e}")))?
+                .unwrap_or(StatusCode::NOT_FOUND);
+            app.fallback(move || async move { (code, not_found) })
+        } else {
+            //app.fallback(handler)
+            let code = fallback
+                .code
+                .map(StatusCode::from_u16)
+                .transpose()
+                .map_err(|e| Error::Message(format!("{e}")))?
+                .unwrap_or(StatusCode::NOT_FOUND);
+            let content = include_str!("fallback.html");
+            app.fallback(move || async move { (code, Html(content)) })
+        };
+        tracing::info!("[Middleware] +fallback");
+        Ok(app)
+    }
+
     fn add_request_id_middleware(app: AXRouter<AppContext>) -> AXRouter<AppContext> {
         let app = app.layer(axum::middleware::from_fn(request_id_middleware));
         tracing::info!("[Middleware] +request id");