Nginx can't find upstream host in multi-container docker compose setup - docker

Question

I'm running a multi-docker container locally with docker-compose, the containers are React front-end 'client', a Nodejs app 'api', and a Nginx proxy in sits in front of two. I have been using the docker-compose setup as follow for a while
version: '3'
services:
client:
build:
dockerfile: Dockerfile.dev
context: ./client
volumes:
- /usr/app/node_modules
- ./client:/usr/app
api:
build:
dockerfile: Dockerfile.dev
context: ./server
volumes:
- /usr/app/node_modules
- ./server:/usr/app
nginx:
restart: always
build:
dockerfile: Dockerfile.dev
context: ./nginx
ports:
- '8080:80'
and my Nginx setup is as follows
upstream client {
server client:3000;
}
upstream api {
server api:5000;
}
server {
listen 80;
server_name _;
location / {
if ($http_x_forwarded_proto != 'https') {
return 301 https://$host$request_uri;
}
proxy_pass http://client;
}
location /api {
if ($http_x_forwarded_proto != 'https') {
return 301 https://$host$request_uri;
}
rewrite /api/(.*) /$1 break;
proxy_pass http://api;
}
}
Recently when I tried to start up the containers, i got following error:
nginx_1 | 2019/08/08 18:11:12 [emerg] 1#1: host not found in upstream "client:3000" in /etc/nginx/conf.d/default.conf:2
nginx_1 | nginx: [emerg] host not found in upstream "client:3000" in /etc/nginx/conf.d/default.conf:2
Any idea why nginx not able to find upstream?
I have tried to add links to nginx setup blocks as follows:
nginx:
restart: always
build:
dockerfile: Dockerfile.dev
context: ./nginx
links:
- client:client
- api:api
ports:
- '8080:80'
I also tried 'depends_on' instead of links. After adding links, nginx no longer complains and exit with code 0. But when i visit the localhost:8080,
it gives a 301 redirect to https://localhost.
Any help or direction are greatly appreciated!!!

Answer 1

You should check names of your services. Docker compose will start your service api in pod named [YOUR_PROJECT_NAME]_api_1. Start only api and client and check output of docker ps. You should gey list of names of pods.
In newer docker_compose syntax versions you can use link_external to map [YOUR_PROJECT_NAME]_api_1 to api.