# Error while attempting to disable login

**Apache Airflow version**: 2.0.0
**Kubernetes version (if you are using kubernetes)** (use `kubectl version`):

**Environment**:

- **Cloud provider or hardware configuration**: mac-pro
- **OS** (e.g. from /etc/os-release): osx
- **Kernel** (e.g. `uname -a`): Darwin C02CW1JLMD6R 19.6.0 Darwin Kernel Version 19.6.0: Mon Aug 31 22:12:52 PDT 2020; root:xnu-6153.141.2~1/RELEASE_X86_64 x86_64
- **Install tools**:
- **Others**:

**What happened**:

When setting in `webserver_config.py`,
```python
AUTH_ROLE_PUBLIC = 'Admin'
```

Got error on webserver, when going to localhost:8080/home,
```log
[2020-12-17 16:29:09,993] {app.py:1891} ERROR - Exception on /home [GET]
Traceback (most recent call last):
  File "/Users/Zshot0831/.local/share/virtualenvs/airflow_2-DimIlKMl/lib/python3.8/site-packages/flask/app.py", line 2447, in wsgi_app
    response = self.full_dispatch_request()
  File "/Users/Zshot0831/.local/share/virtualenvs/airflow_2-DimIlKMl/lib/python3.8/site-packages/flask/app.py", line 1952, in full_dispatch_request
    rv = self.handle_user_exception(e)
  File "/Users/Zshot0831/.local/share/virtualenvs/airflow_2-DimIlKMl/lib/python3.8/site-packages/flask/app.py", line 1821, in handle_user_exception
    reraise(exc_type, exc_value, tb)
  File "/Users/Zshot0831/.local/share/virtualenvs/airflow_2-DimIlKMl/lib/python3.8/site-packages/flask/_compat.py", line 39, in reraise
    raise value
  File "/Users/Zshot0831/.local/share/virtualenvs/airflow_2-DimIlKMl/lib/python3.8/site-packages/flask/app.py", line 1950, in full_dispatch_request
    rv = self.dispatch_request()
  File "/Users/Zshot0831/.local/share/virtualenvs/airflow_2-DimIlKMl/lib/python3.8/site-packages/flask/app.py", line 1936, in dispatch_request
    return self.view_functions[rule.endpoint](**req.view_args)
  File "/Users/Zshot0831/.local/share/virtualenvs/airflow_2-DimIlKMl/lib/python3.8/site-packages/airflow/www/auth.py", line 34, in decorated
    return func(*args, **kwargs)
  File "/Users/Zshot0831/.local/share/virtualenvs/airflow_2-DimIlKMl/lib/python3.8/site-packages/airflow/www/views.py", line 540, in index
    user_permissions = current_app.appbuilder.sm.get_all_permissions_views()
  File "/Users/Zshot0831/.local/share/virtualenvs/airflow_2-DimIlKMl/lib/python3.8/site-packages/airflow/www/security.py", line 226, in get_all_permissions_views
    for role in self.get_user_roles():
  File "/Users/Zshot0831/.local/share/virtualenvs/airflow_2-DimIlKMl/lib/python3.8/site-packages/airflow/www/security.py", line 219, in get_user_roles
    public_role = current_app.appbuilder.config.get('AUTH_ROLE_PUBLIC')
AttributeError: 'AirflowAppBuilder' object has no attribute 'config'
```


**What you expected to happen**:

Reached homepage without the need for authentication as admin.

**How to reproduce it**:
1. Install airflow in a new environment (or to a new directory, set env AIRFLOW_HOME=[my new dir])
2. Uncomment and change in webserver_config.py 
    ```python
    AUTH_ROLE_PUBLIC = 'Admin'
    ```
3. Start `airflow webserver`
4. Look in localhost:8080/home or localhost:8080

*webserver_config.py file**
```python
#
# Licensed to the Apache Software Foundation (ASF) under one
# or more contributor license agreements.  See the NOTICE file
# distributed with this work for additional information
# regarding copyright ownership.  The ASF licenses this file
# to you under the Apache License, Version 2.0 (the
# "License"); you may not use this file except in compliance
# with the License.  You may obtain a copy of the License at
#
#   http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing,
# software distributed under the License is distributed on an
# "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
# KIND, either express or implied.  See the License for the
# specific language governing permissions and limitations
# under the License.
"""Default configuration for the Airflow webserver"""
import os

from flask_appbuilder.security.manager import AUTH_DB

# from flask_appbuilder.security.manager import AUTH_LDAP
# from flask_appbuilder.security.manager import AUTH_OAUTH
# from flask_appbuilder.security.manager import AUTH_OID
# from flask_appbuilder.security.manager import AUTH_REMOTE_USER


basedir = os.path.abspath(os.path.dirname(__file__))

# Flask-WTF flag for CSRF
WTF_CSRF_ENABLED = True

# ----------------------------------------------------
# AUTHENTICATION CONFIG
# ----------------------------------------------------
# For details on how to set up each of the following authentication, see
# http://flask-appbuilder.readthedocs.io/en/latest/security.html# authentication-methods
# for details.

# The authentication type
# AUTH_OID : Is for OpenID
# AUTH_DB : Is for database
# AUTH_LDAP : Is for LDAP
# AUTH_REMOTE_USER : Is for using REMOTE_USER from web server
# AUTH_OAUTH : Is for OAuth
AUTH_TYPE = AUTH_DB

# Uncomment to setup Full admin role name
# AUTH_ROLE_ADMIN = 'Admin'

# Uncomment to setup Public role name, no authentication needed
AUTH_ROLE_PUBLIC = 'Admin'

# Will allow user self registration
# AUTH_USER_REGISTRATION = True

# The default user self registration role
# AUTH_USER_REGISTRATION_ROLE = "Public"

# When using OAuth Auth, uncomment to setup provider(s) info
# Google OAuth example:
# OAUTH_PROVIDERS = [{
#   'name':'google',
#     'token_key':'access_token',
#     'icon':'fa-google',
#         'remote_app': {
#             'api_base_url':'https://www.googleapis.com/oauth2/v2/',
#             'client_kwargs':{
#                 'scope': 'email profile'
#             },
#             'access_token_url':'https://accounts.google.com/o/oauth2/token',
#             'authorize_url':'https://accounts.google.com/o/oauth2/auth',
#             'request_token_url': None,
#             'client_id': GOOGLE_KEY,
#             'client_secret': GOOGLE_SECRET_KEY,
#         }
# }]

# When using LDAP Auth, setup the ldap server
# AUTH_LDAP_SERVER = "ldap://ldapserver.new"

# When using OpenID Auth, uncomment to setup OpenID providers.
# example for OpenID authentication
# OPENID_PROVIDERS = [
#    { 'name': 'Yahoo', 'url': 'https://me.yahoo.com' },
#    { 'name': 'AOL', 'url': 'http://openid.aol.com/<username>' },
#    { 'name': 'Flickr', 'url': 'http://www.flickr.com/<username>' },
#    { 'name': 'MyOpenID', 'url': 'https://www.myopenid.com' }]

# ----------------------------------------------------
# Theme CONFIG
# ----------------------------------------------------
# Flask App Builder comes up with a number of predefined themes
# that you can use for Apache Airflow.
# http://flask-appbuilder.readthedocs.io/en/latest/customizing.html#changing-themes
# Please make sure to remove "navbar_color" configuration from airflow.cfg
# in order to fully utilize the theme. (or use that property in conjunction with theme)
# APP_THEME = "bootstrap-theme.css"  # default bootstrap
# APP_THEME = "amelia.css"
# APP_THEME = "cerulean.css"
# APP_THEME = "cosmo.css"
# APP_THEME = "cyborg.css"
# APP_THEME = "darkly.css"
# APP_THEME = "flatly.css"
# APP_THEME = "journal.css"
# APP_THEME = "lumen.css"
# APP_THEME = "paper.css"
# APP_THEME = "readable.css"
# APP_THEME = "sandstone.css"
# APP_THEME = "simplex.css"
# APP_THEME = "slate.css"
# APP_THEME = "solar.css"
# APP_THEME = "spacelab.css"
# APP_THEME = "superhero.css"
# APP_THEME = "united.css"
# APP_THEME = "yeti.css"
```

![Screen Shot 2020-12-17 at 4 37 06 PM](https://user-images.githubusercontent.com/3694482/102546943-64733800-4086-11eb-8dd7-6a36b2b8ee82.png)

tests/www/test_security.py
#
#
#
import logging
import unittest
from unittest import mock
from flask_appbuilder import SQLA, Model, expose, has_access
from flask_appbuilder.security.sqla import models as sqla_models
from flask_appbuilder.views import BaseView, ModelView
from sqlalchemy import Column, Date, Float, Integer, String
from airflow import settings
from airflow.exceptions import AirflowException
from airflow.models import DagModel
from airflow.security import permissions
from airflow.www import app as application
from airflow.www.utils import CustomSQLAInterface
from tests.test_utils import fab_utils
from tests.test_utils.db import clear_db_dags, clear_db_runs
from tests.test_utils.mock_security_manager import MockSecurityManager
READ_WRITE = {permissions.ACTION_CAN_READ, permissions.ACTION_CAN_EDIT}
READ_ONLY = {permissions.ACTION_CAN_READ}
logging.basicConfig(format='%(asctime)s:%(levelname)s:%(name)s:%(message)s')
logging.getLogger().setLevel(logging.DEBUG)
log = logging.getLogger(__name__)
class SomeModel(Model):