this is just a question about theory, my app is running perfectly...
So, I have 3 services runing with docker-compose: a postgres database, a backend springboot and a frontend angular.
From what I know, docker containers can acess ports from other docker containers without the need to expose the port, so there is no need to expose nor bind the ports because they are all containers and can access each other with the default bridge network mode (that's what I learned, don't know if this is right).
I only need to expose the port from the frontend container so I can access from my localhost.
The thing is: I can access the database with the backend (backend -> database) without the need of exporting any ports, but with the frontend (frontend -> backend) using angular with nginx, it only works with the backend port exposed, why?
docker-compose.yml:
version: "3"
services:
### DATABASE ###
db:
image: postgres:latest
container_name: mydb
network_mode: bridge
environment:
- POSTGRES_PASSWORD=envpass
- POSTGRES_USER=envuser
- POSTGRES_DB=database
# It works without exposing
# expose:
# - 5432
# ports:
# - 5433:5432
### BACKEND ###
backend:
image: angularback
container_name: backend
network_mode: bridge
expose:
- 8080
ports:
- 8082:8080
depends_on:
- db
links:
- db
### FRONTEND ###
frontend:
image: angularfront
container_name: frontend
network_mode: bridge
expose:
- 80
ports:
- 8084:80
depends_on:
- backend
links:
- backend
You Angular frontend is making requests to the Spring backend from outside the frontend container. It's making request from inside your browser. That's why the backend also needs to be exposed.
Second, you don't need links. The linking will be done automatically since both services are in the same network.
Here is a updated config, that uses networks instead:
version: "3"
services:
### DATABASE ###
db:
image: postgres:latest
environment:
- POSTGRES_PASSWORD=envpass
- POSTGRES_USER=envuser
- POSTGRES_DB=database
# Only add the ports here, if you want to access the database using an external client.
# ports:
# - "5433:5432"
networks:
- backend
### BACKEND ###
backend:
image: angularback
ports:
- "8082:8080"
depends_on:
- db
networks:
- backend
- frontend
### FRONTEND ###
frontend:
image: angularfront
ports:
- "8084:80"
depends_on:
- backend
networks:
- frontend
networks:
backend:
frontend:
When not running in production, I'd also recommend to bind the ports all directly to the host interface (127.0.0.1), to prevent others in your network to access the port on your machine, like this:
ports:
- "127.0.0.1:8084:80"