Nginx - Is it possible to use load balancer with external urls? - nginx

Question

My problem is the following:
I have 2 web applications, a "Normal" and an "Expensive". The "Normal" communicates with the "Expensive" for expensive tasks. In order to improve speeds and reduce bottlenecks the plan is deploy at least a couple of the "Expensive" app in 2 different machines and use a load balancer to split the requests (Instead of having a NASA PC, having 2 or more regular PCs).
The apps are made in Gunicorn + Django and served through sockets with Nginx. (No Docker or weird stuff, at much a Supervisor to keep things alive)
Current systems works perfectly, but it could go faster for certains tasks, that's why the load balancer. However I'm incapable of making the load balancer works using server addresses which are not in the same machine (no localhost:port, x.x.x.x, x.x.x.x:port, or urls included in /etc/hosts)
This is a balancer.conf that worked in my local using local apps
upstream balancer {
# least_conn;
server 192.168.22.200:8000;
server 192.168.22.200:8001;
}
server {
listen 80;
server_name localhost;
location / {
proxy_set_header Host $host;
proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
proxy_set_header X-Forwarded-Protocol $scheme;
proxy_set_header X-Real-IP $remote_addr;
proxy_read_timeout 120;
proxy_redirect off;
proxy_pass http://balancer;
}
}
And this is my last attempt to make it work with remote servers (I need the SSL stuff because it is forced on them)
upstream balancer {
# least_conn;
server external.machine.com;
}
server {
listen 80;
server_name test.url.com;
return 301 https://$server_name$1;
}
server {
listen 443 ssl http2;
server_name test.url.com;
# Turn on SSL
ssl on;
<exactly the same stuff I have in the others .conf for the ssl>
resolver 8.8.8.8 8.8.4.4 valid=300s;
resolver_timeout 5s;
location / {
# proxy_set_header Host $host;
proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
# proxy_set_header X-Forwarded-Protocol $scheme;
# proxy_set_header X-Real-IP $remote_addr;
# proxy_read_timeout 120;
# proxy_redirect off;
proxy_pass http://balancer;
}
}
To clarify and remember: external.machine.com and test.url.com are not in the same machine. They have different public IPs. And in the external.machine.com, I have configured an Nginx that serves the "Expensive" app correctly.
I'm unable to find anything related or people who have tried this, everything single post or documentation I found is related or done with local IPs, instead of regular URLs for external IPs.
So I have now the question whether is it possible to use the Nginx load balancer with remote IPs or only with local ones

Answer 1

Yes, you can use outer urls BUT you need to specify the port. Or at least that's how I made it works.
Said that, the nginx configuration file will be something like this:
upstream balancer {
# least_conn;
server external.machine.com:<CUSTOM_PORT>;
}
server {
listen 80;
server_name test.url.com;
return 301 https://$server_name$1;
}
server {
listen 443 ssl http2;
server_name test.url.com;
# Turn on SSL
ssl on;
<exactly the same stuff I have in the others .conf for the ssl>
resolver 8.8.8.8 8.8.4.4 valid=300s;
resolver_timeout 5s;
location / {
proxy_set_header Host $host;
proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
proxy_set_header X-Forwarded-Protocol $scheme;
proxy_set_header X-Real-IP $remote_addr;
proxy_read_timeout 120;
proxy_redirect off;
proxy_pass http://balancer;
}
}
Obviously you need to open that port in the machine
And in the pointed machine your nginx file must look like this
upstream wsgi_socket {
server unix:/tmp/socket.sock fail_timeout=0;
}
server {
# listen [::]:80 ipv6only=on;
listen 80;
server_name test.url.com; # same server name as is the balancer.conf
return 301 https://$server_name$1;
}
server {
listen <CUSTOM POST> ssl http2;
server_name test.url.com; # same server name as is the balancer.conf
root <path to your proejct root>;
client_max_body_size 15M;
# You can configure access_log and error_log too
# Turn on SSL
ssl on;
<all the ssl stuff>
resolver 8.8.8.8 8.8.4.4 valid=300s;
resolver_timeout 5s;
location /static {
alias <path to your static if you have statics>;
}
location / {
# checks for static file, if not found proxy to app
try_files $uri #proxy_to_app;
}
location #proxy_to_app {
proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
proxy_set_header Host $host;
proxy_set_header X-Forwarded-Protocol $scheme;
proxy_read_timeout 120;
proxy_redirect off;
proxy_pass http://unix:/tmp/socket.sock;
}
}