Add Checking and Force Flag for Directory in Serve Command (#2265)

* Introduce option to force directory when running the serve command

* Update documentation about the force flag on the serve command

* Resolve cargo fmt issue

* Reword new serve flag documentation

docs/content/documentation/getting-started/cli-usage.md

@@ -81,6 +81,8 @@ web browser.
 
 Before starting, Zola will delete the output directory (by default `public` in project root) to start from a clean slate.
 
+If you are specifying the directory but are also using the `output-dir` flag, Zola will not use the specified directory if it already exists unless the --force flag is used.
+
 ```bash
 $ zola serve
 $ zola serve --port 2000

src/cli.rs

@@ -65,6 +65,10 @@ pub enum Command {
         #[clap(short = 'o', long)]
         output_dir: Option<PathBuf>,
 
+        /// Force use of the directory for serving the site even if output directory is non-empty
+        #[clap(long)]
+        force: bool,
+
         /// Changes the base_url
         #[clap(short = 'u', long, default_value = "127.0.0.1")]
         base_url: String,

src/cmd/serve.rs

@@ -47,7 +47,7 @@ use libs::serde_json;
 use notify::{watcher, RecursiveMode, Watcher};
 use ws::{Message, Sender, WebSocket};
 
-use errors::{anyhow, Context, Result};
+use errors::{anyhow, Context, Error, Result};
 use pathdiff::diff_paths;
 use site::sass::compile_sass;
 use site::{Site, SITE_CONTENT};
@@ -324,6 +324,7 @@ fn create_new_site(
     interface: &str,
     interface_port: u16,
     output_dir: Option<&Path>,
+    force: bool,
     base_url: &str,
     config_file: &Path,
     include_drafts: bool,
@@ -354,6 +355,12 @@ fn create_new_site(
     site.enable_serve_mode();
     site.set_base_url(base_url);
     if let Some(output_dir) = output_dir {
+        if !force && output_dir.exists() {
+            return Err(Error::msg(format!(
+                "Directory '{}' already exists. Use --force to overwrite.",
+                output_dir.display(),
+            )));
+        }
         site.set_output_path(output_dir);
     }
     if include_drafts {
@@ -377,6 +384,7 @@ pub fn serve(
     interface: &str,
     interface_port: u16,
     output_dir: Option<&Path>,
+    force: bool,
     base_url: &str,
     config_file: &Path,
     open: bool,
@@ -391,6 +399,7 @@ pub fn serve(
         interface,
         interface_port,
         output_dir,
+        force,
         base_url,
         config_file,
         include_drafts,
@@ -599,6 +608,7 @@ pub fn serve(
         interface,
         interface_port,
         output_dir,
+        force,
         base_url,
         config_file,
         include_drafts,

src/main.rs

@@ -79,6 +79,7 @@ fn main() {
             interface,
             mut port,
             output_dir,
+            force,
             base_url,
             drafts,
             open,
@@ -104,6 +105,7 @@ fn main() {
                 &interface,
                 port,
                 output_dir.as_deref(),
+                force,
                 &base_url,
                 &config_file,
                 open,