Add optional arg to serve for extra paths to watch for changes (#2745)

* Add optional arg to serve for extra paths to watch for changes

* Address feedback

src/cli.rs

@@ -89,6 +89,10 @@ pub enum Command {
         /// Default append port to the base url.
         #[clap(long)]
         no_port_append: bool,
+
+        /// Extra path to watch for changes, relative to the project root.
+        #[clap(long)]
+        extra_watch_path: Vec<String>,
     },
 
     /// Try to build the project without rendering it. Checks links

src/cmd/serve.rs

@@ -430,6 +430,7 @@ pub fn serve(
     fast_rebuild: bool,
     no_port_append: bool,
     utc_offset: UtcOffset,
+    extra_watch_paths: Vec<String>,
 ) -> Result<()> {
     let start = Instant::now();
     let (mut site, bind_address, constructed_base_url) = create_new_site(
@@ -462,8 +463,8 @@ pub fn serve(
     // An array of (path, WatchMode, RecursiveMode) where the path is watched for changes,
     // the WatchMode value indicates whether this path must exist for zola serve to operate,
     // and the RecursiveMode value indicates whether to watch nested directories.
-    let watch_this = vec![
-        // The first entry is ultimtely to watch config.toml in a more robust manner on Linux when
+    let mut watch_this = vec![
+        // The first entry is ultimately to watch config.toml in a more robust manner on Linux when
         // the file changes by way of a caching strategy used by editors such as vim.
         // https://github.com/getzola/zola/issues/2266
         (root_dir_str, WatchMode::Required, RecursiveMode::NonRecursive),
@@ -473,6 +474,11 @@ pub fn serve(
         ("templates", WatchMode::Optional, RecursiveMode::Recursive),
         ("themes", WatchMode::Condition(site.config.theme.is_some()), RecursiveMode::Recursive),
     ];
+    watch_this.extend(
+        extra_watch_paths
+            .iter()
+            .map(|path| (path.as_str(), WatchMode::Required, RecursiveMode::Recursive)),
+    );
 
     // Setup watchers
     let (tx, rx) = channel();
@@ -810,6 +816,23 @@ pub fn serve(
                                 site = s;
                             }
                         }
+                        ChangeKind::ExtraPath => {
+                            let full_paths: Vec<&PathBuf> =
+                                change_group.iter().map(|(_, p, _)| p).collect();
+                            let combined_paths = full_paths
+                                .iter()
+                                .map(|p| p.display().to_string())
+                                .collect::<Vec<String>>()
+                                .join(", ");
+                            console::info(&format!(
+                                "-> {combined_paths} changed. Recreating whole site."
+                            ));
+
+                            // We can't know exactly what to update when a user provides the path.
+                            if let Some(s) = recreate_site() {
+                                site = s;
+                            }
+                        }
                     };
                     messages::report_elapsed_time(start);
                 }

src/fs_utils.rs

@@ -17,6 +17,8 @@ pub enum ChangeKind {
     StaticFiles,
     Sass,
     Config,
+    /// A change in one of the extra paths to watch provided by the user.
+    ExtraPath,
 }
 
 /// This enum abstracts over the fine-grained group of enums in `notify`.
@@ -160,7 +162,7 @@ fn detect_change_kind(pwd: &Path, path: &Path, config_path: &Path) -> (ChangeKin
     } else if path == config_path {
         ChangeKind::Config
     } else {
-        unreachable!("Got a change in an unexpected path: {}", partial_path.display());
+        ChangeKind::ExtraPath
     };
 
     (change_kind, partial_path)

src/main.rs

@@ -86,6 +86,7 @@ fn main() {
             open,
             fast,
             no_port_append,
+            extra_watch_path,
         } => {
             if port != 1111 && !port_is_available(port) {
                 console::error("The requested port is not available");
@@ -114,6 +115,7 @@ fn main() {
                 fast,
                 no_port_append,
                 UtcOffset::current_local_offset().unwrap_or(UtcOffset::UTC),
+                extra_watch_path,
             ) {
                 messages::unravel_errors("Failed to serve the site", &e);
                 std::process::exit(1);