Balancing several gateways in Docker - docker

Question

Is there any possibility to create several gateway docker containers with balanced access via the same URL?
I have now the following compose yaml file
version: "3.9"
services:
gateway:
image: "foo/gateway"
ports:
- "8888"
networks:
- "my-net"
deploy:
replicas: 5
x-scaling: "4-7"
factorial:
image: "foo/factorial"
expose:
- "8081"
networks:
- "my-net"
deploy:
replicas: 3
x-scaling: "2-4"
fibonacci:
image: "foo/fibonacci"
expose:
- "8082"
networks:
- "my-net"
deploy:
replicas: 2
x-scaling: "1-3"
networks:
my-net:
driver: "bridge"
Now I have 3 factorial containers, 2 fibonacci containers, and 5 gateway containers with different ports. Each gateway container has access to some of the factorial/fibonacci replicas, but I need to specify a port of the gateway.
Is there any way to provide one URL to a gateway and have requests balanced between gateway replicas by Docker?
Actually, I'm going to create an ECS cluster with docker-compose and ecs context, but this config doesn't provide me any balancing as I could see.

Answer 1

You can user nginx. Put you backend behind nginx and load balance them in your nginx. Something like below.
upstream backend
{
server factorial:8001;
server fibonacci:8002;
}
location /
{
proxy_pass http://backend/;
proxy_set_header Host $host;
proxy_set_header X-Forwarded-For $remote_addr;
proxy_set_header X-Forwarded-Proto https;
}