got session id working.

src/main.rs

@@ -1,10 +1,7 @@
-use axum::{
-    response::IntoResponse,
-    routing::get,
-    Router,
-};
-use axum_extra::extract::cookie::{CookieJar, Cookie};
+use axum::{response::IntoResponse, routing::get, Router};
+use axum_extra::extract::cookie::{Cookie, CookieJar};
 use clap::Parser;
+use rand::distributions::{Alphanumeric, DistString};
 
 const LOCALHOST: &str = "127.0.0.1";
 const SESSION_KEY: &str = "sessionid";
@@ -32,8 +29,7 @@ mod http_session {
 async fn main() {
     let args = Args::parse();
     let addr = format!("{}:{}", args.address, args.port);
-    let app = Router::new()
-        .route("/", get(handler));
+    let app = Router::new().route("/", get(handler));
     let listener = tokio::net::TcpListener::bind(&addr).await.unwrap();
     axum::serve(listener, app.into_make_service())
         .await
@@ -47,10 +43,11 @@ async fn handler(jar: CookieJar) -> impl IntoResponse {
         Some(session) => {
             id = session.to_string();
             cookies = jar;
-        },
+        }
         None => {
-            id = "Fred".to_string();
-            cookies = jar.add(Cookie::new(SESSION_KEY, id.clone()));
+            id = Alphanumeric.sample_string(&mut rand::thread_rng(), 16);
+            let cookie = Cookie::build((SESSION_KEY, id.clone())).domain("example.com");
+            cookies = jar.add(cookie);
         }
     }
     (cookies, format!("id is {}", id))