So everything was working great but due to the nature of my site and it's users, SSL is required, especially since I'll be using SSO exclusively for login. Once I enabled SSL I started receiving both 400 and 522 errors on a certain amount of the socket.io polls. I'm not certain what the percentage is of failed polling attempts but it's not 100% because the site still works and some data still makes it through.
Here's a screenshot of the errors in my safari console (yes, it happens in chrome and firefox too)
And here's my nginx vhost config
server {
listen 80;
server_name forum.nzb.cat;
return 301 https://forum.nzb.cat$request_uri;
}
server {
listen 443 ssl;
server_name forum.nzb.cat;
ssl_certificate /etc/nginx/ssl/forum.nzb.cat.crt;
ssl_certificate_key /etc/nginx/ssl/nzbcat.key;
location / {
proxy_set_header X-Real-IP $remote_addr;
proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
proxy_set_header Host $http_host;
proxy_set_header X-NginX-Proxy true;
proxy_pass http://127.0.0.1:4567/;
proxy_redirect off;
# Socket.IO Support
proxy_http_version 1.1;
proxy_set_header Upgrade $http_upgrade;
proxy_set_header Connection "upgrade";
}
}
And here's the error in the nginx error.log. I googled and googled and did everything the stack overflow people suggested to no avail:
2015/04/12 10:39:03 [error] 17037#0: *146836 upstream prematurely closed connection while reading response header from upstream, client: xxx.xxx.xxx.xxx, server: forum.nzb.cat, request: "GET /socket.io/?EIO=3&transport=polling&t=1428849532722-383&sid=ECw2nTDnOQgEjGcdAAKp HTTP/1.1", upstream: "http://127.0.0.1:4567/socket.io/?EIO=3&transport=polling&t=1428849532722-383&sid=ECw2nTDnOQgEjGcdAAKp", host: "forum.nzb.cat", referrer: "https://forum.nzb.cat/"
I'm at my wit's end here so any help would be appreciated. I didn't bother commenting out any of the URL's as it's a public site.
I had a hard time too while configuring. Try this one:
### redirects http requests to https
server {
listen 80;
server_name forum.example.org;
return 301 https://forum.example.org$request_uri;
}
### the https server
server {
# listen on ssl, deliver with speedy if possible
listen 443 ssl spdy;
server_name forum.example.org;
ssl on;
# change this path!
ssl_certificate /path/to/cert/bundle.crt;
# change this path!
ssl_certificate_key /path/to/cert/forum.example.org.key;
# enables all versions of TLS, but not SSLv2 or 3 which are weak and now deprecated.
ssl_protocols TLSv1 TLSv1.1 TLSv1.2;
# disables all weak ciphers
ssl_ciphers 'AES128+EECDH:AES128+EDH';
ssl_prefer_server_ciphers on;
location / {
proxy_set_header X-Real-IP $remote_addr;
proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
proxy_set_header Host $http_host;
proxy_set_header X-NginX-Proxy true;
proxy_pass http://127.0.0.1:4567/;
proxy_redirect off;
# Socket.IO Support
proxy_http_version 1.1;
proxy_set_header Upgrade $http_upgrade;
proxy_set_header Connection "upgrade";
}
}
Alternatively, my working configuration for clustering enabled + SSL:
# redirects http requests to https
server {
listen 80;
# change this!
server_name example.com;
# change this!
return 301 https://example.com$request_uri;
}
# create multiple instances for scaling
upstream io_nodes {
ip_hash;
server 127.0.0.1:4567;
server 127.0.0.1:4568;
server 127.0.0.1:4569;
}
# the actual encrypted server
server {
listen 443 ssl spdy;
# change this!
server_name example.com;
ssl on;
# change this!
ssl_certificate /etc/nginx/ssl/bundle.crt;
#change this!
ssl_certificate_key /etc/nginx/ssl/site.de.key;
# enables all versions of TLS, but not SSLv2 or 3 which are weak and now deprecated.
ssl_protocols TLSv1 TLSv1.1 TLSv1.2;
# disables all weak ciphers
ssl_ciphers 'AES128+EECDH:AES128+EDH';
ssl_prefer_server_ciphers on;
proxy_set_header X-Real-IP $remote_addr;
proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
proxy_set_header Host $http_host;
proxy_set_header X-NginX-Proxy true;
proxy_redirect off;
# Socket.io Support
proxy_http_version 1.1;
proxy_set_header Upgrade $http_upgrade;
# watch out - no quotes!
proxy_set_header Connection upgrade;
gzip on;
gzip_min_length 1000;
gzip_proxied off;
gzip_types text/plain application/xml application/x-javascript text/css application/json;
location @nodebb {
proxy_pass http://io_nodes;
}
location ~ ^/(images|language|sounds|templates|uploads|vendor|src\/modules|nodebb\.min\.js|stylesheet\.css|admin\.css) {
# change this!
root /var/www/nodebb/public/;
try_files $uri $uri/ @nodebb;
}
location / {
proxy_pass http://io_nodes;
}
}
@KingCat , if you run sudo nginx -t, what happens exactly?
@julian said:
It's cloudflare. Keep using it, but disable acceleration. Websocket issues will be fixed.
I did what you suggested and it seems to have fixed the issue in chrome. However in safari it still happens. I'm gonna wait a while and see if maybe safari just has something weird cached (even though i cleared browser and dns cache).
So it's been a few days and i'm still getting the errors in safari. The errors don't show up in any other browser though.
If I had to guess, I'd say theres some kind of technology or protocol that safari doesn't support (maybe the wss:// protocol?) so the socket.io has to fallback to using http instead and that seems to be why the error happens. Totally a guess though.
If this is the best I can do I'm OK with that as 0.1% of my users are on safari and it's not a site-breaking bug either. I'll consider this closed unless anyone has anything else to try.
Also, not sure if it matters but I'm using a free StartSSL certificate. It's not a self-signed one and it gives the green lock in safari but just in case it matters for some reason.
By the way, I visited the link in the error messages in safari (https://forum.nzb.cat/socket.io/?EIO=3&transport=polling&t=1429031828694-10&sid=E7eEDbKPU53mKENvAAW3)
and got this:
I'm behind cloud flare ssl so I'm not sure if that's what's causing it (even though I disabled it completely for awhile and it still happened)
{"code":1,"message":"Session ID unknown"}
Not sure what this means for the cause of the 400/502 errors.
@KingCat I don't really have anything to contribute, just wanted to say that I saw your username and went "... NZBCat?" and lo and behold... Two things I use combined together 
Welp, I solved it.
Turns out I had the wrong directory specified in nginx for static assets. It was pointing to a different install of nodebb. For some reason that caused issues with socket.io (and only with safari/opera for some reason).
Now, here's the weird thing. I only recently started using nginx to serve the assets. Recently as in like this morning. Before that I simply had a proxy pass setup and let nodebb serve the assets. I'm not sure what was causing the 400/502 errors then but I'm just glad their solved now.
