health check (#688)

Creates a health check route which just returns 200 OK.

src/server.rs

@@ -152,6 +152,7 @@ pub async fn bind_from_listener(
     listener: TcpListener,
 ) -> anyhow::Result<()> {
     let router = Router::new()
+        // Operate on identity commitments
         .route("/verifySemaphoreProof", post(verify_semaphore_proof))
         .route("/inclusionProof", post(inclusion_proof))
         .route("/insertIdentity", post(insert_identity))
@@ -162,6 +163,8 @@ pub async fn bind_from_listener(
         .route("/addBatchSize", post(add_batch_size))
         .route("/removeBatchSize", post(remove_batch_size))
         .route("/listBatchSizes", get(list_batch_sizes))
+        // Health check, return 200 OK
+        .route("/health", get(()))
         .layer(middleware::from_fn(
             custom_middleware::api_metrics_layer::middleware,
         ))

tests/common/mod.rs

@@ -598,13 +598,14 @@ pub async fn spawn_app(config: Config) -> anyhow::Result<(JoinHandle<()>, Socket
     let listener = TcpListener::bind(server_config.address).expect("Failed to bind random port");
     let local_addr = listener.local_addr()?;
 
-    // For our tests to work we need the tree to be initialised so we
-    // need to sleep for a short moment.
+    // For our tests to work we need the tree to be initialized.
     while app.tree_state().is_err() {
         trace!("Waiting for the tree to be initialized");
         tokio::time::sleep(Duration::from_millis(250)).await;
     }
 
+    check_health(&local_addr).await?;
+
     let app = spawn({
         async move {
             info!("App thread starting");
@@ -618,6 +619,25 @@ pub async fn spawn_app(config: Config) -> anyhow::Result<(JoinHandle<()>, Socket
     Ok((app, local_addr))
 }
 
+pub async fn check_health(socket_addr: &SocketAddr) -> anyhow::Result<()> {
+    let uri = format!("http://{}", socket_addr);
+    let client = Client::new();
+    let req = Request::builder()
+        .method("GET")
+        .uri(uri.to_owned() + "/health")
+        .body(Body::empty())
+        .expect("Failed to create health check hyper::Body");
+    let response = client
+        .request(req)
+        .await
+        .context("Failed to execute health check request.")?;
+    if !response.status().is_success() {
+        anyhow::bail!("Health check failed");
+    }
+
+    Ok(())
+}
+
 #[derive(Deserialize, Serialize, Debug)]
 struct CompiledContract {
     abi:      Abi,