Socket.io, Express 4 and Nginx with SSL *AND CLUSTER* throw a 400 (Bad Request)? - node.js

Question

I'm using nginx for web-facing traffic and proxying my node.js connections, as well as handling my SSL.
The connection IS successfully established--io.on('connection') does trigger a console log server side, but then I get a 400 (Bad Request) on the client (in both Firefox and Chrome) and then the connection resets over and over (and continues throwing the same error).
The error is as follows (from Chrome):
polling-xhr.js:264 GET https://192.168.56.101/socket.io/?EIO=3&transport=polling&t=M54C3iW&sid=byqOIkctI9uWOAU2AAAA 400 (Bad Request)
i.create # polling-xhr.js:264
i # polling-xhr.js:165
o.request # polling-xhr.js:92
o.doPoll # polling-xhr.js:122
n.poll # polling.js:118
n.onData # polling.js:157
(anonymous) # polling-xhr.js:125
n.emit # index.js:133
i.onData # polling-xhr.js:299
i.onLoad # polling-xhr.js:366
hasXDR.r.onreadystatechange # polling-xhr.js:252
XMLHttpRequest.send (async)
i.create # polling-xhr.js:264
i # polling-xhr.js:165
o.request # polling-xhr.js:92
o.doPoll # polling-xhr.js:122
n.poll # polling.js:118
n.doOpen # polling.js:63
n.open # transport.js:80
n.open # socket.js:245
n # socket.js:119
n # socket.js:28
n.open.n.connect # manager.js:226
n # manager.js:69
n # manager.js:37
n # index.js:60
(anonymous) # control.js:6
192.168.56.101/:1 WebSocket connection to 'wss://192.168.56.101/socket.io/?EIO=3&transport=websocket&sid=byqOIkctI9uWOAU2AAAA' failed: WebSocket is closed before the connection is established.
Nginx logs (at info level) show the following:
2018/01/29 19:37:10 [info] 28262#28262: *18403 client closed connection while waiting for request, client: 192.168.56.1, server: 192.168.56.101:443
My nginx config is as follows
(I HAVE tried this both with and without the "location /socket.io/ " block, and get exactly the same results.):
map $http_upgrade $connection_upgrade {
default upgrade;
'' close;
}
upstream altairServer {
server 192.168.56.101:8000;
}
server {
listen 192.168.56.101:443;
server_name altair.e6diaspora.com;
ssl on;
ssl_certificate /home/e6serv/crypto/domain.pem;
ssl_certificate_key /home/e6serv/crypto/server.key;
access_log /home/e6serv/logs/nginx/host.access.log;
error_log /home/e6serv/logs/nginx/host.error.log;
root /home/e6serv/e6Code/e6GS1/public;
location / {
try_files maintain.html $uri $uri/index.html #node;
}
location /socket.io/ {
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://altairServer;
proxy_redirect off;
proxy_http_version 1.1;
proxy_set_header Upgrade $http_upgrade;
proxy_set_header Connection "upgrade";
}
location #node {
proxy_pass http://altairServer;
proxy_http_version 1.1;
proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
proxy_set_header X-Real-IP $remote_addr;
proxy_set_header Host $host;
proxy_set_header X-NginX-Proxy true;
proxy_set_header Upgrade $http_upgrade;
proxy_set_header Connection "Upgrade";
proxy_max_temp_file_size 0;
proxy_redirect off;
proxy_read_timeout 240s;
}
}
The relevant server side code is as follows:
const app = express();
app.set('port', 8000);
app.engine('html', require('ejs').renderFile);
app.use(methodOverride());
app.use(session({
secret: SITE_SECRET,
store: redisSesStore,
cookie: {maxAge: 604800000},
resave: false,
saveUninitialized: false
}));
app.use(parseCookie());
app.use(bodyParser.json());
app.use(bodyParser.urlencoded({ extended: true }));
app.use('/',router);
const httpServer = http.createServer(app)
const io = socketIo.listen(httpServer);
io.use(passportSocketIo.authorize({
key: 'connect.sid',
secret: SITE_SECRET,
store: redisSesStore,
passport: passport,
cookieParser: parseCookie
}));
httpServer.listen(app.get('port'), '192.168.56.101', function(){
log.warn('Worker Started HTTP Server')
});
io.on('connection', function(socket) {
log.debug(socket.request.user)
var event = { type:'userConnect',data:'Hello Client'};
process.send(event);
}
My client side code is as follows:
control.socket = io.connect('https://'+hostname);
console.log("Should be connected")
//NOTE: This final line does not work--the console.log never fires:
control.socket.on('userConnect',function (data) {console.log(data)})

Answer 1

I've discovered the source of the problem... The extra element that was in here that I didn't know to talk about was node.js's Cluster.
https://github.com/socketio/socket.io/issues/1942
https://socket.io/docs/using-multiple-nodes/
Socket.io defaults to polling, which requires a sticky load balancing between the various workers. The solution was as found in the socket.io multiple node documentation.
I added something like the following to my nginx config:
upstream io_nodes {
ip_hash;
server 127.0.0.1:6001;
server 127.0.0.1:6002;
server 127.0.0.1:6003;
server 127.0.0.1:6004;
}
(Also note, specific workers must be set up to listen on specific ports.)