Intermittent 502 errors for websites hosted in FRA & AMS

This is an intermittent issue. So far today, we have seen the “502 Bad Gateway” error at these times:

01:58
02:10
02:24
09:50

We test 15 websites every 2 minutes, so these 4 errors were reported after running the test ~5,000 times.

I do not have a ticket number for this.

We have been seeing these errors since last week.

Our servers are in Frankfurt.

One of our domains where we’ve seen this issue is cinafilm.com.

Here’s the output of curl -v https://www.cinafilm.com/cdn-cgi/trace

* About to connect() to www.cinafilm.com port 443 (#0)
*   Trying 104.21.2.170...
* Connected to www.cinafilm.com (104.21.2.170) port 443 (#0)
* Initializing NSS with certpath: sql:/etc/pki/nssdb
*   CAfile: /etc/pki/tls/certs/ca-bundle.crt
  CApath: none
* SSL connection using TLS_ECDHE_ECDSA_WITH_AES_128_GCM_SHA256
* Server certificate:
*       subject: CN=sni.cloudflaressl.com,O="Cloudflare, Inc.",L=San Francisco,ST=CA,C=US
*       start date: Aug 07 00:00:00 2020 GMT
*       expire date: Aug 07 12:00:00 2021 GMT
*       common name: sni.cloudflaressl.com
*       issuer: CN=Cloudflare Inc ECC CA-3,O="Cloudflare, Inc.",C=US
> GET /cdn-cgi/trace HTTP/1.1
> User-Agent: curl/7.29.0
> Host: www.cinafilm.com
> Accept: */*
>
< HTTP/1.1 200 OK
< Date: Mon, 21 Jun 2021 11:39:24 GMT
< Content-Type: text/plain
< Transfer-Encoding: chunked
< Connection: keep-alive
< Access-Control-Allow-Origin: *
< Server: cloudflare
< CF-RAY: 662cf4c44d774eaa-FRA
< X-Frame-Options: DENY
< X-Content-Type-Options: nosniff
< Expires: Thu, 01 Jan 1970 00:00:01 GMT
< Cache-Control: no-cache
<
fl=71f672
h=www.cinafilm.com
ip=178.162.193.20
ts=1624275564.21
visit_scheme=https
uag=curl/7.29.0
colo=FRA
http=http/1.1
loc=DE
tls=TLSv1.2
sni=plaintext
warp=off
gateway=off
* Connection #0 to host www.cinafilm.com left intact