Environment variables not expanded in bundles

[stub42]

Documentation claims environment variables are expanded in the jinja2 bundle overlays. However, zaza.charm_lifecycle.deploy never accesses os.environ nor passes it through to jinja2 as context.

2020-06-01 19:23:18 [ERROR] Template error. You may be missing a mandatory environment variable : 'HOME' is undefined

[gnuoy]

Hi @stub42,
zaza.charm_lifecycle.deploy accesses the environment variables via get_deployment_context() *1 The documentation fails to mention that not all environment variables are added to the jinja2 context, they are first filtered by prefix *2

*1 https://github.com/openstack-charmers/zaza/blob/master/zaza/charm_lifecycle/deploy.py#L71
*2 https://github.com/openstack-charmers/zaza/blob/master/zaza/utilities/deployment_env.py#L35

[gnuoy]

...and get_template_overlay_context is badly named too given it is used for the bundle and overlay contexts.

[stub42]

Discovered the prefix whitelist in deployment_env.py. Given it is recommended to run via tox, which requires you to whitelist environment variables explicitly, the extra whitelist in deployment_env.py could be dropped.