Setting a variable name as the service

I need to put a variable name on the service in my yml file used to deploy a feature branch from gitlab into Rancher. The variable will be from gitlab -> CI_COMMIT_REF_SLUG. I have tried to get the name feature to be the variable. The yml setup keeps deploying the word “feature” as the name for the subdomain that appears at

What do I need to change in my yml to get the ${CI_COMMIT_REF_SLUG} to be deployed as the subdomain?

Here is my feature.yml file.

version: ‘2’
container_name: {CI_COMMIT_REF_SLUG} image:{CI_BUILD_REF}
- “4500”
sxg.service.type: web
sxg.service.port: 4500
port: 4500
request_line: GET / HTTP/1.0
interval: 10000
healthy_threshold: 2
unhealthy_threshold: 3
response_timeout: 10000