Config file variable substitution

1

Hello folks!
I looked cli/main.py how config works with environment variables.
But I feel lack of variable reuse.
For example, the following code will not work:

HTTP_BIND_IFACE: 0.0.0.0
HTTP_BIND_PORT: 8080
HTTP_URI: http://${HTTP_BIND_IFACE}:${HTTP_BIND_PORT}

Here is the result:

>>> n.config
{'HTTP_BIND_IFACE': '0.0.0.0', 'HTTP_BIND_PORT': 8080,
'HTTP_URI': {'http://': None}

Jinja2 substitution does not work either:

HTTP_BIND_IFACE: 0.0.0.0
HTTP_BIND_PORT: 8080
HTTP_URI: "http://{{HTTP_BIND_IFACE}}:{{var_HTTP_BIND_PORT}}

Results in:

>>> n.config
{'HTTP_BIND_IFACE': '0.0.0.0', 'HTTP_BIND_PORT': 8080,
'HTTP_URI': 'http://{{HTTP_BIND_IFACE}}:{{HTTP_BIND_PORT}}'

Please advise.
Thanks!