@asbach, thanks for your PR! By analyzing the history of the files in this pull request, we identified @tmcneal, @balloob and @mmaret-geny to be potential reviewers.

These environment lines aren't necessary I believe. Any python executables installed inside a virtualenv have their python executable specifically defined.

For example, my hass executable looks like this:

#!/srv/homeassistant/homeassistant_venv/bin/python3

# -*- coding: utf-8 -*-
import re
import sys

from homeassistant.__main__ import main

if __name__ == '__main__':
    sys.argv[0] = re.sub(r'(-script\.pyw?|\.exe)?$', '', sys.argv[0])
    sys.exit(main())

Note the hashbang line.

@asbach This doesn't work
Using $ in Environment is not allowed.

The resulting path is "$VIRTUAL_ENV/bin:$PATH" (literally)

@andrey-git I just reread the docs and as you already noticed, unit files do not support variable expansion in the Environment= directive.
Are there any objections to using the style as suggested by @WeeBull?

I don't understand his proposal.

For me I just replaced "$VIRTUAL_ENV/bin:$PATH" by manually expanded values.

Because the virtualenv already creates binaries with a hashbang pointing to the correct binary of Python. Setting the PATH is most likely not required. Maybe one of the main developers can jump in? Does home assistant depend on a correct PATH in relation to the virtual environment binaries?