I am attempting to parameterize a databricks yaml so I can deploy it to multiple databricks accounts via Gitlab CICD, and have ran into a snag when parameterizing the workpace host value. 
My variable block looks like this: 
variables:
    databricks_host:
        description: Databricks host URL
        default: <my_url>
 
And I reference the variable like so: 
 
workspace:
    host: ${var.databricks_host}
 
I set the variable with BUNDLE_VAR_databricks_host: <url> 
in the Gitlab CI pipeline. I have verified that this pattern works with other variables, it is just this variable reference that won't resolve. 
 
This is the error I get: 
Error: failed during request visitor: parse "https://${var.databricks_host}": invalid character "{" in host name
56 Host: ${var.databricks_host}  
I am beginning to think that this particular value cannot be assigned with a variable, but I haven't found anything in the documentation to backup that assumption. Any help would be greatly appreciated!