Nginx 502 Bad Gateway error on EC2 Instance - node.js

Question

I've been having some trouble configuring an nginx server on a EC2 Linux instance. I'm running an application on port 3000 and want to map that to port 80 using nginx.
Here is my configuration file:
user nginx;
worker_processes auto;
error_log /var/log/nginx/error.log;
pid /var/run/nginx.pid;
include /usr/share/nginx/modules/*.conf;
events {
worker_connections 1024;
}
http {
log_format main '$remote-addr - $remote_user [$time_local] "$request" '
'$status $body_bytes_sent "$http_referer" '
'"$http_user_agent" "$http_x_forwarded_for"';
access_log /var/log/nginx/access.log main;
sendfile on;
top_nopush on;
tcp_nodelay on;
keepalive_timeout 65;
types_hash_max_size 2048;
server_names_hash_bucket_size 128;
include /etc/nginx/mime.types;
default_type application/octet-stream;
include /etc/nginx/conf.d/*.conf;
index index.html index.htm
server {
listen 80 default_server;
[::]:80 default_server;
server_name localhost;
include /etc/nginx/default.d/*.conf;
location / {
}
error_page 404 /404.html;
location =/40x.html {
}
error_page 500 502 503 504 /50x.html;
location =/50x.html {
}
}
include /etc/nginx/sites-enabled/default;
This is the default file that comes with nginx with very slight changes by me, most notably the inclusion of a custom file called default, whose contents are as follows:
server {
listen 80;
server_name [my_domain_name];
location / {
proxy_pass http://[my_private_ip]:3000;
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;
}
}
With the items in square brackets replaced with the correct values. Whenever I try to navigate to the website I get 502 Bad Gateway nginx/1.12.1.
My server is a node.js server running on port 3000.
I've tried troubleshooting and reading other stackoverflow questions about bad gateways but I can't figure out the solution. Thank you

Answer 1

Follow a different approach. Allow your application to run on port 3000 (and listen on 3000 as well). In this case, you would then have to open it as
http://url:3000
Now we just need to forward all requests coming to port 80 to 3000 which can be easily done using iptables:
sudo iptables -A PREROUTING -t nat -i eth0 -p tcp --dport 80 -j REDIRECT --to-port 3000
Now you should be simply able to open it with the url, without the port number