Add cache-control headers to API responses

sync-server/src/bin/taskchampion-sync-server.rs

@@ -1,10 +1,21 @@
 #![deny(clippy::all)]
 
-use actix_web::{middleware::Logger, App, HttpServer};
+use actix_web::{middleware, middleware::Logger, App, HttpServer};
 use clap::Arg;
 use taskchampion_sync_server::storage::SqliteStorage;
 use taskchampion_sync_server::Server;
 
+// The `.wrap` method returns an opaque type, meaning that we can't easily return it from
+// functions.  So, we must apply these default headers when the app is created, which occurs both
+// in `main` and in the tests.  To check that those are both doing precisely the same thing, we use
+// a macro.  This is ugly, and will go away when actix-web is no longer the framework in use.
+macro_rules! cache_control_headers {
+    ($wrapped:expr) => {
+        $wrapped
+            .wrap(middleware::DefaultHeaders::new().header("Cache-Control", "no-store, max-age=0"))
+    };
+}
+
 #[actix_web::main]
 async fn main() -> anyhow::Result<()> {
     env_logger::init();
@@ -39,10 +50,14 @@ async fn main() -> anyhow::Result<()> {
     let server = Server::new(Box::new(SqliteStorage::new(data_dir)?));
 
     log::warn!("Serving on port {}", port);
-    HttpServer::new(move || App::new().wrap(Logger::default()).service(server.service()))
-        .bind(format!("0.0.0.0:{}", port))?
-        .run()
-        .await?;
+    HttpServer::new(move || {
+        cache_control_headers!(App::new())
+            .wrap(Logger::default())
+            .service(server.service())
+    })
+    .bind(format!("0.0.0.0:{}", port))?
+    .run()
+    .await?;
     Ok(())
 }
 
@@ -50,15 +65,20 @@ async fn main() -> anyhow::Result<()> {
 mod test {
     use super::*;
     use actix_web::{test, App};
-    use taskchampion_sync_server::storage::{InMemoryStorage, Storage};
+    use taskchampion_sync_server::storage::InMemoryStorage;
 
     #[actix_rt::test]
     async fn test_index_get() {
         let server = Server::new(Box::new(InMemoryStorage::new()));
-        let mut app = test::init_service(App::new().service(server.service())).await;
+        let app = cache_control_headers!(App::new()).service(server.service());
+        let mut app = test::init_service(app).await;
 
         let req = test::TestRequest::get().uri("/").to_request();
         let resp = test::call_service(&mut app, req).await;
         assert!(resp.status().is_success());
+        assert_eq!(
+            resp.headers().get("Cache-Control").unwrap(),
+            &"no-store, max-age=0".to_string()
+        )
     }
 }