SSL / stunnel + haproxy + nginx Problem :)

[lr1980]

Infos:

• Used Zammad version: 2.3
• Used Zammad installation source: centos repo
• Operating system: centos 7
• Browser + version: multiple

Actual behavior:

nginx error log:

2018/02/13 09:04:29 [error] 1818#0: *37748 upstream prematurely closed connection while reading response 
header from upstream, client: 1.2.3.4, server: XXX, request: "GET /ws HTTP/1.1", 
upstream: "http://127.0.0.1:6042/ws", host: "XXX"

nginx config:

upstream zammad-railsserver {
    server localhost:3000;
}

upstream zammad-websocket {
    server localhost:6042;
}

server {
    listen 80;

    # replace 'localhost' with your fqdn if you want to use zammad from remote
    server_name XXX;

    set_real_ip_from XXX/16;
    set_real_ip_from 127.0.0.1/32;
    real_ip_header X-Forwarded-For;
    real_ip_recursive on;

    root /opt/zammad/public;

    access_log /var/log/nginx/zammad.access.log;
    error_log  /var/log/nginx/zammad.error.log;

    client_max_body_size 50M;

    location ~ ^/(assets/|robots.txt|humans.txt|favicon.ico) {
        expires max;
    }

    location /ws {
        proxy_http_version 1.1;
        proxy_set_header Upgrade $http_upgrade;
        proxy_set_header Connection "Upgrade";
        proxy_set_header CLIENT_IP $remote_addr;
        proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
        proxy_set_header X-Forwarded-Proto $scheme;
        proxy_read_timeout 86400;
        proxy_pass http://zammad-websocket;
    }

    location / {
        proxy_set_header Host $http_host;
        proxy_set_header CLIENT_IP $remote_addr;
        proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
        proxy_set_header X-Forwarded-Proto $scheme;
        proxy_read_timeout 300;
        proxy_pass http://zammad-railsserver;

        gzip on;
        gzip_types text/plain text/xml text/css image/svg+xml application/javascript application/x-javascript application/json application/xml;
        gzip_proxied any;
    }
}

Is there a option to set a higher log lever or is there any other way to find the error?

[lr1980]

I resolved this problem => our varnish was the problem => https://varnish-cache.org/docs/3.0/tutorial/websockets.html