Allow environment variables substitition in yaml files

[Luiscri]

It would be useful if environment variables substitution was allowed for yaml files. An usage example would be refering to a different table according to the environment we are:

entities:
  MY_TABLE:
    source_database: BIGQUERY
    table_name: ${GOOGLE_CLOUD_PROJECT}.mydataset.mytable
...

# or

rule_bindings:
  MY_BINDING:
    entity_uri: bigquery://projects/${GOOGLE_CLOUD_PROJECT}/datasets/mydataset/tables/mytable
...

[thinhha]

Hi @Luiscri thanks for the suggestion. I think this would be a great feature. I estimate this effort to be quite large as we will need to make a few important decisions on how to allow interpolating environment variables into the YAML configs. I will update this ticket when we are able to prioritize this work.

[victorbrub]

That would be really helpful for my project actually. There's a plan for this implementation?