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I have a simple web application running in a docker container and exposed on port 81.
curl http://127.0.0.1:81 returns the index.html of that web app. So it is running and is reachable. Also localhost or using the browser it works.

Now I added a container with Nginx.
I want to redirect the calls to port 80 to the web app. This is my simplest /etc/nginx/nginx.conf file:

events {}
http {
    server {
        listen 80;

    location / {
        proxy_pass http://127.0.0.1:81;            
        #proxy_pass http://google.com;
    }
}



}

Switching the proxy_pass to the one pointing to Google it works, so I assume the error is because nginx is not able to "communicate" with the web app (also that is what I read about nginx and 502 error).

I access to the nginx instance with docker -it <container-name> /bin/bash but then cat /var/log/nginx/error.log or cat /var/log/nginx/access.log or tail doesn't work (kind of enter in edit mode but there is no content).

After this simple step is done I'd like to use upstream to ahave a load balancer over 2 web app instances, so something like this:

events {}

http {
    upstream api {
        server 127.0.0.1:81;
    }


server {
    listen 80 default;
    #listen [::]:80;
    #access_log /dev/stdout;

    proxy_set_header Host $host;
    proxy_set_header X-Real-IP $remote_addr;
    proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;

    location / {
        #proxy_pass http://127.0.0.1:81;            
        #proxy_pass http://google.com;
        proxy_pass http://api;                       

        proxy_redirect     off;
    }
}



}

Again, this does not work.

Alex 75
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    At first glance your problem appears that for an application running inside a container the localhost/127.0.0.1 address effectively means "this container" and not "this server". For your nginx container to connect to another container (running on the same server) you need to connect to either the public/external IP-address where the port is exposed of you set up a container network where the nginx can connect directly to the web application. – Rob Jul 25 '22 at 12:57

0 Answers0