Websocket Cloudflare with Nginx 520 error

问题

I am jumping in on a project with some socket issues over SSL and Cloudflare... I know.. I have read about 50 different stack overflow posts and 200 blog posts to try to figure this out. The project works on my local dev server/computer just fine...

I think I am on the right track - But could use some help/pointers if ya'll can.

First, I thought it was weird that the /socket-io/ proxy_pass was at port 6379, the same as redis... Maybe it should be? When this was set at 6379, the socket connection will not connect - With or Without Cloudflare enabled ( I paused cloudflare to test this out).

I read through the express server and saw that the socket server seems like it's linked to the express server at port 4000... so I changed the proxy_pass for /socket-io/ to port 4000 and it reconnects. This works with Cloudflare paused/running... so maybe it's not cloudflare after all. Still, even though it says the socket has reconnected in the browser, nothing is working.

I'll start by sharing my NGINX config - Let me know what else ya'll need to see, please. Thanks for taking your time to help me out/pointing me in the right direction! I really appreciate learning about this stuff.

server {
  listen 443 ssl;
  listen [::]:443 ssl;
  server_name dev-app.myapp.com;

  location / {
    root /var/www/myapp_frontend/build/;
    try_files $uri $uri/ /index.html;
    #proxy_pass http://localhost:8080;
    proxy_http_version 1.1;
    proxy_set_header Upgrade $http_upgrade;
    proxy_set_header Connection "upgrade";
    proxy_set_header Host $host;
  }

  location /api/ {
    proxy_pass http://localhost:4000/;
    include /etc/nginx/proxy_params;
    proxy_http_version 1.1;
    proxy_set_header Upgrade $http_upgrade;
    proxy_set_header Connection 'upgrade';
    proxy_set_header Host $host;
    proxy_cache_bypass $http_upgrade;
  }

  location /socket.io/ {
    proxy_pass http://localhost:6379;
    proxy_http_version 1.1;
    proxy_set_header Upgrade $http_upgrade;
    proxy_set_header Connection 'upgrade';
    proxy_read_timeout 86400;
  }

location ~ \.php$ {
    include snippets/fastcgi-php.conf;
    fastcgi_pass unix:/run/php/php7.0-fpm.sock;
  }
  location ~ /\.ht {
    deny all;
  }

  ssl_certificate /etc/letsencrypt/live/dev-app.myapp.com/fullchain.pem; # managed by Certbot
  ssl_certificate_key /etc/letsencrypt/live/dev-app.myapp.com/privkey.pem; # managed by Certbot
  include /etc/letsencrypt/options-ssl-nginx.conf; # managed by Certbot
  ssl_dhparam /etc/letsencrypt/ssl-dhparams.pem; # managed by Certbot
}
server {
    if ($host = dev-app.myapp.com) {
        return 301 https://$host$request_uri;
    } # managed by Certbot

    server_name  dev-app.myapp.com;
    listen 80 default_server;
    listen [::]:80 default_server;

    return 404; # managed by Certbot
}

Edit-1 I did see that cloudflare requires certain ports... Am I wrong to think that these ports only refer to the initial listening port, for example 443 above, since the proxy_pass ports are all using localhost?

来源：https://stackoverflow.com/questions/65480401/websocket-cloudflare-with-nginx-520-error