Meltano

And another best practice request:

Is it possible to use meltano inhert/override mechanics to add arbitrary env variables to airflow?

Use case: i want to provide to DAG different db connect credentials through custom variable in `dev` and `prod` environments.

As of now, Meltano does accept an env: {} mapping in each environment. We are also working on having a plugin-level env: {} config that also be overrideable per environment but would send those env configs _only_ to airflow and not to other plugins in the environment.

Ideally, DAGs would be first class citizens in meltano, because not everything can be done with DBT or tap/target pair.

<@U06CBKL5W7L> it seems that there is some sort of inconsistency in interpolation of `env` variables.

For example this interpolation would work in `config`, but not in `env`

This works:
```        config:
          default_target_schema: dev_${USER}_${MELTANO_EXTRACT__LOAD_SCHEMA}```
This does not (variable is substituted to empty value):
```  env:
    DAG_PAYPAL_BQ_TABLE_ID: project-xxx.dev_${USER}_raw.paypal_invoices```
`USER` is defined in `.env` file

<@U06BX5HMGNB> - Yes, that sounds correct for where we are at as of now. This is something we're working on actively right now. We'd like to allow interpolation at any level.

:wave: <@U06BX5HMGNB> just to echo <@U06CBKL5W7L>, this is in my current list of issues for this iteration. <https://github.com/meltano/meltano/issues/5983|Here's> the relevant issue with info on the desired behavior, feel free to chime in there with any additional details about your use case.