From 98e027b9666e556d87932bddc711707cd39468a0 Mon Sep 17 00:00:00 2001
From: Bryan Stitt <bryan@satoshiandkin.com>
Date: Wed, 29 Jun 2022 18:22:53 +0000
Subject: [PATCH] status codes on health

---
 TODO.md                         | 1 -
 web3-proxy/src/connections.rs   | 4 ++++
 web3-proxy/src/frontend/http.rs | 9 +++++++++
 web3-proxy/src/frontend/mod.rs  | 4 +++-
 4 files changed, 16 insertions(+), 2 deletions(-)

diff --git a/TODO.md b/TODO.md
index 823c8ef1..0c986394 100644
--- a/TODO.md
+++ b/TODO.md
@@ -30,7 +30,6 @@
   - even after removing a bunch of the locks, the deadlock still happens. i can't reliably reproduce. i just let it run for awhile and it happens.
   - running gdb shows the thread at tokio tungstenite thread is spinning near 100% cpu and none of the rest of the program is proceeding
   - fixed by https://github.com/gakonst/ethers-rs/pull/1287
-- [ ] quick requests/second timer until we have real stats
 - [ ] rpc errors propagate too far. one subscription failing ends the app. isolate the providers more
 - [ ] if web3 proxy gets an http error back, retry another node
 - [ ] endpoint for health checks. if no synced servers, give a 502 error
diff --git a/web3-proxy/src/connections.rs b/web3-proxy/src/connections.rs
index ab36deca..1ceb444b 100644
--- a/web3-proxy/src/connections.rs
+++ b/web3-proxy/src/connections.rs
@@ -315,6 +315,10 @@ impl Web3Connections {
         *self.synced_connections.load().get_head_block_hash()
     }
 
+    pub fn has_synced_rpcs(&self) -> bool {
+        self.synced_connections.load().inner.len() > 0
+    }
+
     /// Send the same request to all the handles. Returning the most common success or most common error.
     #[instrument(skip_all)]
     pub async fn try_send_parallel_requests(
diff --git a/web3-proxy/src/frontend/http.rs b/web3-proxy/src/frontend/http.rs
index 98ff1eae..5e2c50ee 100644
--- a/web3-proxy/src/frontend/http.rs
+++ b/web3-proxy/src/frontend/http.rs
@@ -11,6 +11,15 @@ pub async fn index() -> impl IntoResponse {
     "Hello, World!"
 }
 
+/// Health check page for load balancers to use
+pub async fn health(app: Extension<Arc<Web3ProxyApp>>) -> impl IntoResponse {
+    if app.get_balanced_rpcs().has_synced_rpcs() {
+        (StatusCode::OK, "OK")
+    } else {
+        (StatusCode::SERVICE_UNAVAILABLE, ":(")
+    }
+}
+
 /// Very basic status page
 pub async fn status(app: Extension<Arc<Web3ProxyApp>>) -> impl IntoResponse {
     // TODO: what else should we include? uptime? prometheus?
diff --git a/web3-proxy/src/frontend/mod.rs b/web3-proxy/src/frontend/mod.rs
index b461a4e4..2e91310a 100644
--- a/web3-proxy/src/frontend/mod.rs
+++ b/web3-proxy/src/frontend/mod.rs
@@ -21,8 +21,10 @@ pub async fn run(port: u16, proxy_app: Arc<Web3ProxyApp>) -> anyhow::Result<()>
         .route("/", post(http_proxy::proxy_web3_rpc))
         // `websocket /` goes to `proxy_web3_ws`
         .route("/", get(ws_proxy::websocket_handler))
-        // `GET /index.html` goes to `index` (todo, somehow combine this with http_proxy::proxy_web3_rpc)
+        // `GET /index.html` goes to `index`
         .route("/index.html", get(http::index))
+        // `GET /health` goes to `health`
+        .route("/health", get(http::health))
         // `GET /status` goes to `status`
         .route("/status", get(http::status))
         .layer(Extension(proxy_app));