We use schema:
CloudFlare → HAProxy v.2.4.8 → Nginx-> Tomcat → Application
Sometimes we see error 522 with our clients. Connection cannot be established. From the CF logs it is clear that the connection breaks for 15 seconds https://support.cloudflare.com/hc/en-us/articles/115003011431-Troubleshooting-Cloudflare-5XX-errors#522error
- Before a connection is established, the origin web server does not return a SYN+ACK to Cloudflare within 15 seconds of CloudFlare sending a SYN.
What logging for haproxy can be enabled to determine the cause. Is it internet packet loss or something else?