Add fallback to try to serve index.html when trying to read a directory

Signed-off-by: Radu Matei <[email protected]>

Author: radu-matei

.gitignore

@@ -1 +1,2 @@
 target/
+.spin/

Cargo.toml

@@ -2,7 +2,7 @@
 name = "spin-static-fs"
 version = "0.1.0"
 edition = "2021"
-authors = ["Radu Matei <radu.matei@fermyon.com>"]
+authors = ["Fermyon Engineering <engineering@fermyon.com>"]
 
 [lib]
 crate-type = ["cdylib"]

spin.toml

@@ -2,8 +2,8 @@ spin_version = "1"
 name = "spin-static-fs"
 version = "0.1.0"
 description = "A simple static server for Spin."
-authors = [ "Radu Matei <radu@fermyon.com>" ]
-trigger = {type = "http", base = "/" }
+authors = ["Fermyon Engineering <engineering@fermyon.com>"]
+trigger = { type = "http", base = "/" }
 
 # For more on configuring a component, see: https://spin.fermyon.dev/configuration/
 [[component]]
@@ -13,4 +13,4 @@ files = [{ source = "", destination = "/" }]
 [component.trigger]
 route = "/..."
 [component.build]
-command = "make"
+command = "make"

src/lib.rs

@@ -10,6 +10,7 @@ use std::{
     fs::File,
     hash::{Hash, Hasher},
     io::Read,
+    path::PathBuf,
 };
 
 /// The default value for the cache control header.
@@ -27,6 +28,8 @@ const BROTLI_ENCODING: &str = "br";
 const PATH_INFO_HEADER: &str = "spin-path-info";
 // Environment variable for the fallback path
 const FALLBACK_PATH_ENV: &str = "FALLBACK_PATH";
+/// Directory fallback path (trying to map `/about/` -> `/about/index.html`).
+const DIRECTORY_FALLBACK_PATH: &str = "index.html";
 
 /// Common Content Encodings
 #[derive(Debug, Eq, PartialEq)]
@@ -83,15 +86,29 @@ fn serve(req: Request) -> Result<Response> {
     let body = match FileServer::read(path, &enc) {
         // requested file was found
         Ok(b) => Some(b),
-        Err(e) => match std::env::var(FALLBACK_PATH_ENV) {
-            // try to read the fallback path
-            Ok(fallback_path) => FileServer::read(fallback_path.as_str(), &enc).ok(),
-            // fallback path config not found
-            Err(_) => {
-                eprintln!("Cannot read file: {e:?}");
-                None
+        Err(e) => {
+            // if the error is because the path points to a directory, attempt to read `index.html`
+            // from the directory. This is because most static file generators will generate this
+            // file structure (where `/about` should be mapped to `/about/index.html`).
+            eprintln!("Cannot find file {path}. Attempting fallback.");
+            // TODO: ideally, we would return better errors throughout the implementation.
+            if e.to_string().contains("Is a directory") {
+                let path = PathBuf::from(path).join(DIRECTORY_FALLBACK_PATH);
+                let path = path.to_str().context("cannot convert path to string")?;
+                eprintln!("Attempting fallback {path}");
+                FileServer::read(path, &enc).ok()
+            } else {
+                match std::env::var(FALLBACK_PATH_ENV) {
+                    // try to read the fallback path
+                    Ok(fallback_path) => FileServer::read(fallback_path.as_str(), &enc).ok(),
+                    // fallback path config not found
+                    Err(_) => {
+                        eprintln!("Cannot read file: {e:?}");
+                        None
+                    }
+                }
             }
-        },
+        }
     };
 
     let etag = FileServer::get_etag(body.clone());