Nginx to handle SSL for WebSockets - node.js

Question

I'm very new to Nginx and I'm feeling like a monkey trapped inside a nuclear power plant facility — nothing makes any sense — and I desperately want to get some bananas.
Anyway, I'm using Nginx server for handling SSL and proxying all requests to the NodeJS app. Everything works just fine except for WebSockets. The client gives me an ERR_INSECURE_RESPONSE error. The server is live. What am I missing? What would you advice?
NodeJS
const express = require('express')
const app = express()
const server = require('http').Server(app)
const io = require('socket.io')(server)
app.use(express.static('../app'))
io.on('connection', (socket) => {
console.log('CONNECTED')
})
server.listen(5000)
Nginx config (taken from this tutorial Deploying a NodeJS app with ssl)
# HTTP — redirect all traffic to HTTPS
server {
listen 80;
listen [::]:80 default_server ipv6only=on;
return 301 https://$host$request_uri;
}
# HTTPS — proxy all requests to the Node app
server {
# Enable HTTP/2
listen 443 ssl http2;
listen [::]:443 ssl http2;
server_name olmeo.us;
# Use the Let’s Encrypt certificates
ssl_certificate /etc/letsencrypt/live/olmeo.us/fullchain.pem;
ssl_certificate_key /etc/letsencrypt/live/olmeo.us/privkey.pem;
# Include the SSL configuration from cipherli.st
include snippets/ssl-params.conf;
location / {
proxy_set_header X-Real-IP $remote_addr;
proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
proxy_set_header X-NginX-Proxy true;
proxy_pass http://localhost:5000/;
proxy_ssl_session_reuse off;
proxy_set_header Host $http_host;
proxy_cache_bypass $http_upgrade;
proxy_redirect off;
}
}
SSL config (include snippets/ssl-params.conf)
# See https://cipherli.st/ for details on this configuration
ssl_protocols TLSv1 TLSv1.1 TLSv1.2;
ssl_prefer_server_ciphers on;
ssl_ciphers "EECDH+AESGCM:EDH+AESGCM:AES256+EECDH:AES256+EDH";
ssl_ecdh_curve secp384r1; # Requires nginx >= 1.1.0
ssl_session_cache shared:SSL:10m;
ssl_session_tickets off; # Requires nginx >= 1.5.9
ssl_stapling on; # Requires nginx >= 1.3.7
ssl_stapling_verify on; # Requires nginx => 1.3.7
resolver 8.8.8.8 8.8.4.4 valid=300s;
resolver_timeout 5s;
add_header Strict-Transport-Security "max-age=63072000; includeSubDomains; preload";
add_header X-Frame-Options DENY;
add_header X-Content-Type-Options nosniff;
# Add our strong Diffie-Hellman group
ssl_dhparam /etc/ssl/certs/dhparam.pem;
Client
io.connect('https://52.29.55.217')

Answer 1

Your SSL certificate is likely provided for a given domain, not for the IP address and you are using the IP and not a domain to connect:
io.connect('https://52.29.55.217')
Unless your certificate includes that IP address in the list of hosts that it covers (highly unlikely) then this will not work. Try it with the exact domain name that was used while creating the certificate with Let's Encrypt (not a subdomain, not an IP, the exact domain name).