From 325734518cf024869fb8a7d33cb75b665438a83b Mon Sep 17 00:00:00 2001 From: Nico Flaig Date: Fri, 21 Jul 2023 23:16:34 +0200 Subject: [PATCH] fix: prevent eventstream errors on shutdown or client aborts (#5784) --- packages/api/src/beacon/server/events.ts | 11 +++++++---- 1 file changed, 7 insertions(+), 4 deletions(-) diff --git a/packages/api/src/beacon/server/events.ts b/packages/api/src/beacon/server/events.ts index 0a20e57e908a..fa8b857f8779 100644 --- a/packages/api/src/beacon/server/events.ts +++ b/packages/api/src/beacon/server/events.ts @@ -18,7 +18,13 @@ export function getRoutes(config: ChainForkConfig, api: ServerApi): ServerR const controller = new AbortController(); try { - // Add injected headers from other pluggins. This is required for fastify-cors for example + // Prevent Fastify from sending the response, this is recommended before writing to the `.raw` stream + // and avoids "Cannot set headers after they are sent to the client" errors during shutdown or client aborts. + // See https://github.com/fastify/fastify/issues/3979, https://github.com/ChainSafe/lodestar/issues/5783 + // eslint-disable-next-line @typescript-eslint/no-floating-promises + res.hijack(); + + // Add injected headers from other plugins. This is required for fastify-cors for example // From: https://github.com/NodeFactoryIo/fastify-sse-v2/blob/b1686a979fbf655fb9936c0560294a0c094734d4/src/plugin.ts Object.entries(res.getHeaders()).forEach(([key, value]) => { if (value !== undefined) res.raw.setHeader(key, value); @@ -37,9 +43,6 @@ export function getRoutes(config: ChainForkConfig, api: ServerApi): ServerR await new Promise((resolve, reject) => { void api.eventstream(req.query.topics, controller.signal, (event) => { try { - // If the request is already aborted, we don't need to send any more events. - if (req.raw.destroyed) return; - const data = eventSerdes.toJson(event); res.raw.write(serializeSSEEvent({event: event.type, data})); } catch (e) {