How to connect to Node API docker container from Angular Nginx container - node.js

Question

I am currently working on an angular app using Rest API (Express, Nodejs) and Postgresql. Everything worked well when hosted on my local machine. After testing, I moved the images to Ubuntu server so the app can be hosted on an external port. I am able to access the angular frontend using the https://server-external-ip:80 but when trying to login, Nginx is not connecting to NodeApi. Here is my docker-compose file:
version: '3.0'
services:
db:
image: postgres:9.6-alpine
environment:
POSTGRES_DB: myDb
POSTGRES_PASSWORD: myPwd
ports:
- 5432:5432
restart: always
volumes:
- ./postgres-data:/var/lib/postgresql/data
networks:
- my-network
backend: # name of the second service
image: myId/mynodeapi
ports:
- 3000:3000
environment:
POSTGRES_DB: myDb
POSTGRES_PASSWORD: myPwd
POSTGRES_PORT: 5432
POSTGRES_HOST: db
depends_on:
- db
networks:
- my-network
command: bash -c "sleep 20 && node server.js"
myapp:
image: myId/myangularapp
ports:
- "80:80"
depends_on:
- backend
networks:
- my-network
networks:
my-network:
I am not sure what the apiUrl should be? I have tried the following and nothing worked:
apiUrl: "http://backend:3000/api"
apiUrl: "http://server-external-ip:3000/api"
apiUrl: "http://server-internal-ip:3000/api"
apiUrl: "http://localhost:3000/api"

Answer 1

I think you should use the docker-compose service as a DNS. It seems you've several docker hosts/ports available, there are the following in your docker-compose structure:
db:5432
http://backend:3000
http://myapp
Make sure to use db as POSTGRES_DB in the environment part for backend service.
Take a look to my repo, I think is the best way to learn how a similar project works and how to build several apps with nginx, you also can check my docker-compose.yml, it uses several services and are proxied using nginx and are worked together.
On this link you’ll find a nginx/default.conf file and it contains several nginx upstream configuration please take a look at how I used docker-compose service references there as hosts.
Inside the client/ directory, I also have another nginx as a web server of a react.js project.
On server/ directory, it has a Node.js API, It connects to Redis and Postgres SQL database also built from docker-compose.yml.
If you need set or redirect traffic to /api you can use some ngnix config like this
I think this use case can be useful for you and other users!