node.js - Nginx can't find upstream node app when running via Docker-compose

one text

Solution:

The problem is that in your Nginx configuration you are referencing the IP of the Web service as 127.0.0.1 which is the loopback address of the Host machine running the docker container. This may work depending on your setup (OS, firewall) or may not.

The correct way would be to make the nginx service depends on the web service in your docker-compose.yml file and update the Nginx config to reference the Web service by name (web) instead of by IP address. Here you can find more info related to docker compose depends on capability.

The updated docker-compose.yml file would be:

version: '3.0'
services:
  web:
    build: .
  nginx:
    build:
      context: .
      dockerfile: Dockerfile.nginx
    ports:
      - 8080:8080
    depends_on:
      - web

Notice that I have stop exposing the port of the web service. May be you need to keep it to monitor the Web service but is not required for the nginx service.

With this update to the docker-compose.yml file the Nginx config will be as follows:

events {
  worker_connections  1024;
}

http {

  upstream node_app {
    server web:3000;
  }

  server_tokens off;

  # Define the MIME types for files.
  include       mime.types;
  default_type  application/octet-stream;

  # Speed up file transfers by using sendfile()
  # TODO: Read up on this
  sendfile on;

  server {
    listen 8080;
    server_name localhost;

    location / {
      proxy_pass http://node_app;
      proxy_http_version 1.1;
      proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
      proxy_set_header Host $http_host;
      proxy_set_header X-Real-IP $remote_addr;
    }
  }
}