Passing variables to the Ansible httpapi plugin

Question

I am looking for some help to add one additional variable to the HTTP plugin.

I wanted to pass variable 'ansible_domain' from the inventory or variable file.

I am able to pass to the username and password, but additional variables are not accepted from an inventory file or var file.

The end point required one more parameter to log in for few functions, and I am unable to proceed.

How can I fix this?

I am using Ansible 2.8.

options:
  domain:
    type: str
    description:
      - Specifies the api token path of the FTD device
    env:
      - name: ansible_domain
    vars:
      - name: ansible_domain

"""

import json

from ansible.module_utils.basic import to_text
from ansible.errors import AnsibleConnectionFailure
from ansible.module_utils.six.moves.urllib.error import HTTPError
from ansible.plugins.httpapi import HttpApiBase
from ansible.module_utils.connection import ConnectionError

BASE_HEADERS = {
    'Content-Type': 'application/json',
}
DOMAIN1 = 'domain'

class HttpApi(HttpApiBase):
    def login(self, username, password ):
        if username and password:
            payload = {'user': username, 'password': password, 'domain': DOMAIN1}
            url = '/web_api/login'
            response, response_data = self.send_request(url, payload)
        else:
            raise AnsibleConnectionFailure('Username and password are required for login')

        try:
            self.connection._auth = {'X-chkp-sid': response_data['sid']}
            self.connection._session_uid = response_data['uid']
        except KeyError:
            raise ConnectionError(
                'Server returned response without token info during connection authentication: %s' % response)

    def logout(self):
        url = '/web_api/logout'

        response, dummy = self.send_request(url, None)

    def get_session_uid(self):
        return self.connection._session_uid

    def send_request(self, path, body_params):
        data = json.dumps(body_params) if body_params else '{}'

        try:
            self._display_request()
            response, response_data = self.connection.send(path, data, method='POST', headers=BASE_HEADERS)
            value = self._get_response_value(response_data)

            return response.getcode(), self._response_to_json(value)
        except AnsibleConnectionFailure as e:
            return 404, 'Object not found'
        except HTTPError as e:
            error = json.loads(e.read())
            return e.code, error

    def _display_request(self):
        self.connection.queue_message('vvvv', 'Web Services: %s %s' % ('POST', self.connection._url))

    def _get_response_value(self, response_data):
        return to_text(response_data.getvalue())

    def _response_to_json(self, response_text):
        try:
            return json.loads(response_text) if response_text else {}
        # JSONDecodeError only available on Python 3.5+
        except ValueError:
            raise ConnectionError('Invalid JSON response: %s' % response_text)