Nginx in docker throws 502 Bad Gateway - nginx

Question

I am trying to run a service called Grafana behind Nginx webserver,where both services are being run in a docker-compose file.
docker-compose.yml:
version: '3.1'
services:
nginx:
image: nginx
ports: ['443:443',"80:80"]
restart: always
volumes:
- ./etc/nginx.conf:/etc/nginx/nginx.conf:ro
- /home/ec2-user/certs:/etc/ssl
grafana:
image: grafana/grafana
restart: always
ports: ["3000:3000"]
nginx.conf:
events {
worker_connections 1024;
}
http {
ssl_certificate /etc/ssl/cert.pem;
ssl_certificate_key /etc/ssl/key.pem;
server {
listen 443 ssl;
server_tokens off;
location /grafana/ {
rewrite /grafana/(.*) /$1 break;
proxy_pass http://127.0.0.1:3000/;
proxy_redirect off;
proxy_set_header Host $host;
proxy_set_header X-Real-IP $remote_addr;
proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
proxy_bind $server_addr;
}
}
}
The grafana service is running on port 3000.
My goal is to access this nginx server from outside, (lets assume its public ip address is: 1.1.1.1) on the address https://1.1.1.1/grafana. With the current configuration i get 502 Bad Gateway and the error on nginx side:
(111: Connection refused) while connecting to upstream, client: <<my-public-ip-here>>,

Answer 1

Your containers are running on two separate IP addresses in the docker network, usually 172.17.. by default.
By using a proxy pass like this in the nginx container:
proxy_pass http://127.0.0.1:3000/
You are essentially telling it to look for a process on port 3000 local to itself, because of the 127.0.0.1 right?
You need to point it in the direction of the Grafana container, try doing:
docker inspect <grafana ID> | grep IPAddress
Then set the proxy pass to that IP:
proxy_pass http://172.0.0.?:3000/

Answer 2

I've solved the same issue using something like #james suggested:
docker inspect <your inaccessible container is> | grep Gateway
Then use this IP address:
proxy_pass http://172.xx.0.1:3000/