apollo_http_server: gate is_ready endpoint on accept_new_txs flag (#14206)

* apollo_http_server: gate is_ready endpoint on accept_new_txs flag

When accept_new_txs is false, /gateway/is_ready now returns 503 so the
load balancer drains traffic from this instance instead of routing requests
that the tx handlers would reject anyway. /gateway/is_alive is intentionally
left as a static 200 since liveness should not flip the pod into restart.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

* apollo_http_server: merge is_ready test cases per review

Consolidate is_ready_reflects_accept_new_txs and
is_ready_observes_dynamic_config_updates into a single test that walks the
true -> false -> true lifecycle, since the dynamic-update test already
covers both flag values.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

---------

Co-authored-by: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

Author: matanl-starkware

crates/apollo_http_server/src/http_server.rs

@@ -24,7 +24,7 @@ use apollo_proc_macros::sequencer_latency_histogram;
 use async_trait::async_trait;
 use axum::extract::DefaultBodyLimit;
 use axum::handler::Handler;
-use axum::http::HeaderMap;
+use axum::http::{HeaderMap, StatusCode};
 use axum::routing::{get, post, MethodRouter};
 use axum::{serve, Extension, Json, Router};
 use blockifier_reexecution::serde_utils::deserialize_transaction_json_to_starknet_api_tx;
@@ -139,10 +139,7 @@ impl HttpServer {
                 "/gateway/is_alive",
                 get(|| futures::future::ready("Gateway is alive".to_owned()))
             )
-            .route(
-                "/gateway/is_ready",
-                get(|| futures::future::ready("Gateway is ready".to_owned()))
-            )
+            .route("/gateway/is_ready", get(is_ready))
             .layer(Extension(self.app_state.clone()))
             // Hard streaming limit on decompressed bytes — wraps the body in
             // http_body_util::Limited which errors during poll_frame() once the
@@ -217,6 +214,15 @@ async fn add_tx(
     add_tx_inner(app_state, headers, rpc_tx).await
 }
 
+async fn is_ready(Extension(app_state): Extension<AppState>) -> (StatusCode, &'static str) {
+    let HttpServerDynamicConfig { accept_new_txs, .. } = app_state.get_dynamic_config();
+    if accept_new_txs {
+        (StatusCode::OK, "Gateway is ready")
+    } else {
+        (StatusCode::SERVICE_UNAVAILABLE, "Gateway is not accepting new transactions")
+    }
+}
+
 fn check_new_transactions_are_allowed(accept_new_txs: bool) -> HttpServerResult<()> {
     match accept_new_txs {
         true => Ok(()),

crates/apollo_http_server/src/http_server_test.rs

@@ -1,4 +1,5 @@
 use std::io::Write;
+use std::sync::Arc;
 
 use apollo_gateway_types::communication::{GatewayClientError, MockGatewayClient};
 use apollo_gateway_types::deprecated_gateway_error::{
@@ -13,11 +14,12 @@ use apollo_gateway_types::gateway_types::{
     GatewayOutput,
     InvokeGatewayOutput,
 };
+use apollo_http_server_config::config::HttpServerDynamicConfig;
 use apollo_infra::component_client::ClientError;
 use apollo_proc_macros::unique_u16;
 use axum::body::Bytes;
 use axum::response::{IntoResponse, Response};
-use axum::Json;
+use axum::{Extension, Json};
 use http::StatusCode;
 use http_body_util::BodyExt;
 use rstest::rstest;
@@ -26,10 +28,11 @@ use starknet_api::test_utils::read_json_file;
 use starknet_api::transaction::TransactionHash;
 use starknet_api::{class_hash, contract_address, tx_hash};
 use starknet_types_core::felt::Felt;
+use tokio::sync::watch;
 use tracing_test::traced_test;
 
 use crate::errors::HttpServerError;
-use crate::http_server::CLIENT_REGION_HEADER;
+use crate::http_server::{is_ready, AppState, CLIENT_REGION_HEADER};
 use crate::test_utils::{
     deprecated_gateway_declare_tx,
     deprecated_gateway_deploy_account_tx,
@@ -111,6 +114,27 @@ async fn allow_new_txs() {
     assert_eq!(status, StatusCode::SERVICE_UNAVAILABLE, "{status:?}");
 }
 
+#[tokio::test]
+async fn is_ready_reflects_accept_new_txs() {
+    let (tx, dynamic_config_rx) =
+        watch::channel(HttpServerDynamicConfig { accept_new_txs: true, ..Default::default() });
+    let app_state =
+        AppState { gateway_client: Arc::new(MockGatewayClient::new()), dynamic_config_rx };
+
+    // Clone AppState to mirror how axum's Extension extractor hands a clone to each request:
+    // updates to the watch channel must still be observed through the cloned receiver.
+    let (status, _) = is_ready(Extension(app_state.clone())).await;
+    assert_eq!(status, StatusCode::OK);
+
+    tx.send(HttpServerDynamicConfig { accept_new_txs: false, ..Default::default() }).unwrap();
+    let (status, _) = is_ready(Extension(app_state.clone())).await;
+    assert_eq!(status, StatusCode::SERVICE_UNAVAILABLE);
+
+    tx.send(HttpServerDynamicConfig { accept_new_txs: true, ..Default::default() }).unwrap();
+    let (status, _) = is_ready(Extension(app_state)).await;
+    assert_eq!(status, StatusCode::OK);
+}
+
 #[tokio::test]
 async fn error_into_response() {
     let error = HttpServerError::DeserializationError(