Debugging a basic nginx upstream issue

Question

people of serverfault. Started dabbling in docker with nginx and nodejs, and I'm having a bit of trouble figuring out how to debug my issue here. I'm running 3x nodejs containers and 1x nginx load balancer in front of them.

I can spin up the docker-compose successfully with docker-compose up, but when accessing localhost:8080 I get an nginx 502 with the following error in the console, repeated 3 times (for each node backend):

loadbalancer_1  | 2019/10/05 11:40:31 [error] 6#6: *1 connect() failed (111: Connection refused) while connecting to upstream, client: MY_CLIENT_IP, server: localhost, request: "GET / HTTP/1.1", upstream: "http://172.19.0.4:3000/", host: "MY_PUBLIC_IP:8080"

This is my folder structure:

├── backend
│   ├── Dockerfile
│   └── src
│       ├── index.js
│       └── package-lock.json
├── docker-compose.yml
└── load-balancer
    ├── Dockerfile
    └── nginx.conf

./docker-compose.yml

version: '3.2'
services:
  backend1:
      build: ./backend
      tty: true
      volumes:
        - './backend/src:/backend-dir-inside-container'

  backend2:
      build: ./backend
      tty: true
      volumes:
        - './backend/src:/backend-dir-inside-container'

  backend3:
      build: ./backend
      tty: true
      volumes:
        - './backend/src:/backend-dir-inside-container'

  loadbalancer:
      build: ./load-balancer
      tty: true
      links:
          - backend1
          - backend2
          - backend3
      ports:
          - '8080:8080'

volumes:
  backend:

./backend/Dockerfile

FROM node:boron
LABEL Joe Programmer
RUN mkdir -p /backend-dir-inside-container
WORKDIR /backend-dir-inside-container

FROM node:boron
LABEL Joe Programmer
RUN mkdir -p /backend-dir-inside-container
WORKDIR /backend-dir-inside-container
EXPOSE 3000

./loadbalancer/Dockerfile

FROM nginx
LABEL Joe Programmer
COPY nginx.conf /etc/nginx/nginx.conf

EXPOSE 8080
CMD ["nginx", "-g", "daemon off;"]

And this is my ./loadbalancer/nginx.conf

events { worker_connections 1024; }

http {

 upstream localhost {
    server backend1:3000;
    server backend2:3000;
    server backend3:3000;
 }

 server {
    listen 8080;
    server_name localhost;

    location / {
       proxy_pass http://localhost;
       proxy_set_header Host $host;
    }
  }
}

Besides fixing this issue I'm looking to learn what exactly I'm doing wrong here. Thank you for any or all responses.

Debugging a basic nginx upstream issue

0 Answers0