I do an include of the yml in my databricks.yml. The yml pasted below:

variables:
  my_cluster:
    description: "My cluster definition"
    type: complex
    default:
      spark_version: "13.2.x-scala2.11"
      node_type_id: "Standard_DS3_v2"
      num_workers: 2
      spark_conf:
        spark.speculation: true
        spark.databricks.delta.retentionDurationCheck.enabled: false

resources:
  jobs:
    my_job:
      name: "my_job"
      max_concurrent_runs: 1
      job_clusters:
        - job_cluster_key: my_cluster_key
          new_cluster: ${var.my_cluster}
      tasks:
        - task_key: my_job
          spark_python_task:
            python_file: /Workspace/Shared/.bundle/[...]/specific_task.py
          job_cluster_key: my_cluster_key
          libraries:
            - whl: ../dist/*.whl