Getting started in rancher

I have managed to run rancher server. but would like to have db to be external.

So I used the docker-compose file.
db:
environment:
- MYSQL_DATABASE=cattle
- MYSQL_PASSWORD=cattle
- MYSQL_ROOT_PASSWORD=cattle
- MYSQL_USER=cattle
image: 'mysql:8.0’
ports:
- '3308:3306’
rancher:
environment:
- CATTLE_DB_CATTLE_MYSQL_HOST=db
- CATTLE_DB_CATTLE_MYSQL_NAME=cattle
- CATTLE_DB_CATTLE_MYSQL_PORT=3306
- CATTLE_DB_CATTLE_PASSWORD=cattle
- CATTLE_DB_CATTLE_USERNAME=cattle
image: 'rancher/server:stable’
links:
- db
ports:
- ‘8080:8080’

But keep on getting errors, anyone with a docker-compose file that works great with out any error

Taking a quick look, this seems to be wrong: