how can I use an environment variable in a parameter for a pipe?

I am wanting to use the google-kubectl-pipe which takes numerous arguments which define the kubernetes cluster.

How can I use a variable as part of the variables/parameters for the pipe itself?

In the example below, I want the k8s_zone and k8s_cluster variables to be expanded before they are passed into the pipe.  In this cases, the pipe doesn't do any magic with variables and expected things to be static.

- echo ${k8s_zone}
- pipe: atlassian/google-gke-kubectl-run:1.1.2
  variables:
    KEY_FILE: 'gcloud-api-key.json'
    PROJECT: 'my-cluster-project'
    COMPUTE_ZONE: "${k8s_zone}"
    CLUSTER_NAME: "${k8s_cluster}"