A valid environment variable to satisfy the declaration 'env:url' could not be found

GitLab CI/CD
,
1

Hi need help with this!

I am setting up a VAR named URL in my enviroment gitlab config:

    environment:
        name: staging
        url: https://staging.transferdog.com

I try to access to that variable into my serverless.yml

custom:
  customDomain:
    domainName: ${env:url}

this that my console show me:

41 $ sls deploy --stage staging --env staging --region eu-west-1 --verbose
42
43 Serverless Warning --------------------------------------
44
45 A valid environment variable to satisfy the declaration ‘env:url’ could not be found.
46

please any help with this!

Need to know how to access to my env variables