dict: All environment variables fed to the service.

def env_vars(self):
        """dict: All environment variables fed to the service."""
        if not self.no_libfaketime:
            faketime_filename = self.service_group.hitch_dir.faketime()

            env_vars = dict(os.environ)
            env_vars.update(self._env_vars)
            env_vars.update(faketime.get_environment_vars(faketime_filename))
        else:
            env_vars = dict(os.environ)
            env_vars.update(self._env_vars)
        return env_vars