From 11af938486f2a86d9e07323456e0dd163b5255f6 Mon Sep 17 00:00:00 2001
From: Jakob Ackermann <jakob.ackermann@overleaf.com>
Date: Wed, 21 Jul 2021 13:52:15 +0200
Subject: [PATCH] Merge pull request #4311 from overleaf/tm-cdn-load-errors

Add 1px image from overleaf CDN to layout and report if load fails

GitOrigin-RevId: e1da60d338596db48c0ebb4446bd27e8e1f704ce
---
 services/web/app/views/layout.pug | 8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/services/web/app/views/layout.pug b/services/web/app/views/layout.pug
index 7597c05e97..085eb3447c 100644
--- a/services/web/app/views/layout.pug
+++ b/services/web/app/views/layout.pug
@@ -130,3 +130,11 @@ html(
 					//- Set query param, server will not set CDN url
 					window.location.search += "&nocdn=true";
 				}
+			if hasFeature('saas')
+				script(type="text/javascript", nonce=scriptNonce).
+					//- Test for CDN availability and report to sentry if loading failed
+					var cdnLoadTest = document.createElement('img')
+					cdnLoadTest.addEventListener('error', function () {
+						throw new Error('CDN test image load error (cdn.overleaf.net)')
+					})
+					cdnLoadTest.src = 'https://cdn.overleaf.net/img/1p.gif'