Fabric: Documentation for runtime configuration

I have a bunch of Fabric 1 fabfiles which set env. It's currently non-obvious to migrate that code to Fabric 2. The documentation references e.g. connect_kwargs but there's not much about how or where to set that. After reading through the Invoke docs, it doesn't seem like I can use any of the YAML/JSON configuration options since I need to execute code (in the example below, using keyring to retrieve passwords).

It seemed like something like moving all of it into a fabric.py file might work:

import subprocess
import sys
from getpass import getuser
import os

domain = os.environ.get("DOMAIN", "loctest")

def get_config():
    user = getuser()

    try:
        password = subprocess.check_output(["keyring", "get", domain, user]).strip()
        print("Loaded %s password for %s from keyring" % (domain, user))
    except subprocess.CalledProcessError:
        print(
            "Unable to set password using `keyring` (is it in your PATH?) — expect to be nagged",
            file=sys.stderr,
        )

    return {'user': user, 'password': password}

connect_kwargs = get_config()

Unfortunately, that gets TypeError: can't pickle module objects. Setting __all__ isn't enough to avoid that but moving everything into the function appears to be working:

def get_config():
    import subprocess
    import sys
    from getpass import getuser
    import os

    domain = os.environ.get("DOMAIN", "loctest")
    user = os.environ.get("USER", getuser())

    try:
        password = subprocess.check_output(["keyring", "get", domain, user]).strip()
        print("Loaded %s password for %s from keyring" % (domain, user))
    except subprocess.CalledProcessError:
        print(
            "Unable to set password using `keyring` (is it in your PATH?) — expect to be nagged",
            file=sys.stderr,
        )

    return {"user": user, "password": password}

connect_kwargs = get_config()

Is there / planned to be a cleaner way to do this? Among other things, this code isn't quite equivalent to the Fabric 1 version because it doesn't pull the username in from the config which isn't something I need but it seems like there should be a way to say “Get the processed config and update this one value”.