From ff29540d56362beb5928a32d5381a4e079f7b58a Mon Sep 17 00:00:00 2001
From: Maciej Hirsz <1096222+maciejhirsz@users.noreply.github.com>
Date: Tue, 18 Feb 2020 13:59:12 +0100
Subject: [PATCH] feat: Added a /health endpoint (#230)

---
 backend/src/aggregator.rs | 15 +++++++++++++++
 backend/src/main.rs       | 21 ++++++++++++++++++---
 2 files changed, 33 insertions(+), 3 deletions(-)

diff --git a/backend/src/aggregator.rs b/backend/src/aggregator.rs
index 56a7b45..ab3a5a9 100644
--- a/backend/src/aggregator.rs
+++ b/backend/src/aggregator.rs
@@ -131,10 +131,17 @@ pub struct NodeCount(pub ChainId, pub usize);
 /// Message sent to the Aggregator to get the network state of a particular node
 pub struct GetNetworkState(pub Box<str>, pub NodeId);
 
+/// Message sent to the Aggregator to get a health check
+pub struct GetHealth;
+
 impl Message for GetNetworkState {
     type Result = Option<Request<Chain, GetNodeNetworkState>>;
 }
 
+impl Message for GetHealth {
+    type Result = usize;
+}
+
 impl Handler<AddNode> for Aggregator {
     type Result = ();
 
@@ -264,3 +271,11 @@ impl Handler<GetNetworkState> for Aggregator {
         Some(self.get_chain(&*chain)?.addr.send(GetNodeNetworkState(nid)))
     }
 }
+
+impl Handler<GetHealth> for Aggregator {
+    type Result = usize;
+
+    fn handle(&mut self, _: GetHealth, _: &mut Self::Context) -> Self::Result {
+        self.chains.len()
+    }
+}
diff --git a/backend/src/main.rs b/backend/src/main.rs
index 3a31f3a..e35b411 100644
--- a/backend/src/main.rs
+++ b/backend/src/main.rs
@@ -17,7 +17,7 @@ mod util;
 
 use node::connector::NodeConnector;
 use feed::connector::FeedConnector;
-use aggregator::{Aggregator, GetNetworkState};
+use aggregator::{Aggregator, GetNetworkState, GetHealth};
 use util::{Locator, LocatorFactory};
 use types::NodeId;
 
@@ -77,6 +77,19 @@ fn state_route(
         })
 }
 
+fn health(
+    aggregator: web::Data<Addr<Aggregator>>
+) -> impl Future<Item = HttpResponse, Error = Error> {
+    aggregator
+        .send(GetHealth)
+        .from_err()
+        .and_then(|count| {
+            let body = format!("Connected chains: {}", count);
+
+            HttpResponse::Ok().body(body)
+        })
+}
+
 fn main() -> std::io::Result<()> {
     use web::{resource, get};
 
@@ -86,9 +99,9 @@ fn main() -> std::io::Result<()> {
     let aggregator = Aggregator::new().start();
     let factory = LocatorFactory::new();
     let locator = SyncArbiter::start(4, move || factory.create());
-    
+
     let port = std::env::var("PORT").ok().and_then(|v| v.parse().ok()).unwrap_or(8000u16);
-    
+
     HttpServer::new(move || {
         App::new()
             .data(aggregator.clone())
@@ -99,6 +112,8 @@ fn main() -> std::io::Result<()> {
             .service(resource("/feed/").route(get().to(feed_route)))
             .service(resource("/network_state/{chain}/{nid}").route(get().to_async(state_route)))
             .service(resource("/network_state/{chain}/{nid}/").route(get().to_async(state_route)))
+            .service(resource("/health").route(get().to_async(health)))
+            .service(resource("/health/").route(get().to_async(health)))
     })
     .bind(format!("0.0.0.0:{}", port))?
     .start();