docker-compose service cannot access another service through its name - docker

Question

I am quite new to docker but after watching a few tutorials I gathered that if I wanted my services to have common code I had to use docker-compose.
This is my directory structure:
- project
- docker-compose.yml
- packages
- common
- src
- eureka
- eureka-helper.js
- gateway
- Dockerfile
- src
- (some more directories and files)
- server.js
- users
- Dockerfile
- src
- app.js
- (some more directories and files)
version: '3'
services:
eureka:
image: springcloud/eureka
ports:
- "8761:8761"
gateway:
build:
context: ./
dockerfile: ./packages/gateway/Dockerfile
ports:
- "3000:3000"
links:
- eureka
users:
build:
context: ./
dockerfile: ./users/Dockerfile
ports:
- "3004:3004"
links:
- mongo
- eureka
mongo:
image: mongo
volumes:
- C:\Users\myUser\docker\mongodb-data:/data/db
ports:
- "27017:27017"
My server.js (inside gateway) and app.js (inside users) call a function inside eureka-helper that registers with Eureka.
eurekaHelper.registerWithEureka('gateway', eureka, port);
But it seems that server.js doesn't have a value for this eureka:
gateway_1 | /opt/app/gateway/server.js:27
gateway_1 | eurekaHelper.registerWithEureka('gateway', eureka, port);
gateway_1 | ^
gateway_1 |
gateway_1 | ReferenceError: eureka is not defined
As per this: https://docs.docker.com/compose/networking/, it doesn't seem that I really need the link in docker-compose:
Links allow you to define extra aliases by which a service is reachable from another service. They are not required to enable services to communicate - by default, any service can reach any other service at that service’s name.
... but gateway is not able to reach eureka anyways.
Any idea if I'm missing something.
When I do inspect in gateway:
"Networks": {
"*project*_default": {
"IPAMConfig": null,
"Links": null,
"Aliases": [
"gateway",
"a358b371de9d"
],
"NetworkID": "d986ee77bf6181e9dd59711650359dc49fd8ce3fc34c6772133a0049ab55bd3b",
"EndpointID": "9633a7affe435793345342d4f6d00d5bef43d2267676448dfde0f97d75d5f7af",
"Gateway": "172.19.0.1",
"IPAddress": "172.19.0.3",
"IPPrefixLen": 16,
"IPv6Gateway": "",
"GlobalIPv6Address": "",
"GlobalIPv6PrefixLen": 0,
"MacAddress": "02:42:ac:13:00:03",
"DriverOpts": null
}
}
When I do inspect in eureka:
"Networks": {
"*project*_default": {
"IPAMConfig": null,
"Links": null,
"Aliases": [
"eureka",
"17a218bf6e9e"
],
"NetworkID": "d986ee77bf6181e9dd59711650359dc49fd8ce3fc34c6772133a0049ab55bd3b",
"EndpointID": "43f4a9eb9efd4d30ad65d2c943065b8fb32ed50822bd553e07a2b0020c173fec",
"Gateway": "172.19.0.1",
"IPAddress": "172.19.0.2",
"IPPrefixLen": 16,
"IPv6Gateway": "",
"GlobalIPv6Address": "",
"GlobalIPv6PrefixLen": 0,
"MacAddress": "02:42:ac:13:00:02",
"DriverOpts": null
}
}