container variable expansion

container.yml

version: "2"
settings:
  # The deployment_output_path is mounted to the Conductor container, so
  # that the `run` and `deployment` commands can write generated Ansible
  # playbooks to it.
  # deployment_output_path: ~/ansible-deployment
  # The Conductor container does the heavy lifting, and provides a portable
  # Python runtime for building your target containers. It should be derived
  # from the same distribution as you're building your target containers with.
  conductor_base: centos:7
#  conductor_base: debian:jessie
#  conductor_base: ubuntu:trusty
#  conductor_base: alpine
#  conductor_base: python:3

  # When using the k8s or openshift engines, use the following to authorize with the API.
  # Values set here will be passed to the Ansible modules. Any file paths will be mounted
  # to the conductor container, allowing the `run` command to access the API.
  #k8s_auth:
    # path to a K8s config file
    #config_file:
    # name of a context found within the config.json file
    #context:
    # URL for accessing the K8s API
    #host:
    # An API authentication token
    #api_key:
    # Path to a ca cert file
    #ssl_ca_cert:
    # Path to a cert file
    #cert_file:
    # Path to a key file
    #key_file:
    #boolean, indicating if SSL certs should be validated
    #verify_ssl:

  # When using the k8s or openshift engines, use the following to set the namespace.
  # If not set, the project name will be used. For openshift, the namespace maps to a project,
  # and description and display_name are supported.
  #k8s_namespace:
  #  name:
  #  description:
  #  display_name:

services:
  twisted_cos:
     from: centos:7
     command: ['/twisted_app/venv/bin/python', '/twisted_app/checkout/service.py']
     working_dir: '/twisted_app/checkout'
     roles:
       - twisted_app_cent
     dev_overrides:
       environment:
         - "DEBUG=1"

     environment: {{ environment }}
     
#{% for key, value in environment.items() %}
#       - "{{ key }}={{value }}"
#{% endfor %}

vars.yml

---
git_repo: "site.com/xbar_mbta.git"
environment:
  MBTA_API_ID : "AAABBBCCCDDDEEEFFF"
  XBAR_URL: "ws://192.168.1.1:8080/ws"
  XBAR_REALM: "realm1"