Set the keep alive timeout to 31 seconds (#1111)

* Set the keep alive timeout to 30.5 seconds

* extend window to 31 seconds

* Update .changeset/fair-shrimps-count.md

Co-authored-by: Ryan Ling <ryan@outlook.com.au>

* Update template/koa-rest-api/src/listen.ts

Co-authored-by: Ryan Ling <ryan@outlook.com.au>

* Update template/express-rest-api/src/listen.ts

Co-authored-by: Ryan Ling <ryan@outlook.com.au>

---------

Co-authored-by: Ryan Ling <ryan@outlook.com.au>

.changeset/fair-shrimps-count.md

@@ -0,0 +1,12 @@
+---
+'skuba': patch
+---
+
+template/\*-rest-api: Set `keepAliveTimeout` to 31 seconds to prevent HTTP 502s
+
+The default Node.js server keep-alive timeout is set to 5 seconds. However, the Gantry default ALB idle timeout is 30 seconds. This would lead to the occasional issues where the sidecar would throw `proxyStatus=502` errors. AWS recommends setting an application timeout larger than the ALB idle timeout.
+
+A more detailed explanation can be found in the below links:
+
+1. <https://docs.aws.amazon.com/elasticloadbalancing/latest/application/application-load-balancers.html#connection-idle-timeout>
+2. <https://nodejs.org/docs/latest-v18.x/api/http.html#serverkeepalivetimeout>

template/express-rest-api/src/listen.ts

@@ -14,3 +14,10 @@ const listener = app.listen(config.port, () => {
     rootLogger.debug(`listening on port ${address.port}`);
   }
 });
+
+// Gantry ALB default idle timeout is 30 seconds
+// https://nodejs.org/docs/latest-v18.x/api/http.html#serverkeepalivetimeout
+// Node default is 5 seconds
+// https://docs.aws.amazon.com/elasticloadbalancing/latest/application/application-load-balancers.html#connection-idle-timeout
+// AWS recommends setting an application timeout larger than the load balancer
+listener.keepAliveTimeout = 31000;

template/koa-rest-api/src/listen.ts

@@ -15,3 +15,10 @@ const listener = app.listen(config.port, () => {
     logger.debug(`listening on port ${address.port}`);
   }
 });
+
+// Gantry ALB default idle timeout is 30 seconds
+// https://nodejs.org/docs/latest-v18.x/api/http.html#serverkeepalivetimeout
+// Node default is 5 seconds
+// https://docs.aws.amazon.com/elasticloadbalancing/latest/application/application-load-balancers.html#connection-idle-timeout
+// AWS recommends setting an application timeout larger than the load balancer
+listener.keepAliveTimeout = 31000;