[AIRFLOW-4570] Remove future library (#5324)

Remove all usage of the future library because we're dropping Python 2 support.

airflow/api/auth/backend/kerberos_auth.py

@@ -24,8 +24,6 @@
 # (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
 # SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 
-from future.standard_library import install_aliases
-
 from airflow.utils.log.logging_mixin import LoggingMixin
 
 import kerberos
@@ -43,8 +41,6 @@ from functools import wraps
 from requests_kerberos import HTTPKerberosAuth
 from socket import getfqdn
 
-install_aliases()
-
 client_auth = HTTPKerberosAuth(service='airflow')
 
 _SERVICE_NAME = None

airflow/api/client/json_client.py

@@ -17,7 +17,8 @@
 # specific language governing permissions and limitations
 # under the License.
 
-from future.moves.urllib.parse import urljoin
+from urllib.parse import urljoin
+
 import requests
 
 from airflow.api.client import api_client

airflow/configuration.py

@@ -21,7 +21,6 @@ from base64 import b64encode
 from builtins import str
 from collections import OrderedDict
 import copy
-from future import standard_library
 import os
 import pathlib
 import shlex
@@ -36,8 +35,6 @@ from zope.deprecation import deprecated
 from airflow.exceptions import AirflowConfigException
 from airflow.utils.log.logging_mixin import LoggingMixin
 
-standard_library.install_aliases()
-
 log = LoggingMixin().log
 
 # show Airflow's deprecation warnings

airflow/contrib/auth/backends/ldap_auth.py

@@ -16,7 +16,6 @@
 # KIND, either express or implied.  See the License for the
 # specific language governing permissions and limitations
 # under the License.
-from future.utils import native
 
 import flask_login
 from flask_login import login_required, current_user, logout_user  # noqa: F401
@@ -75,7 +74,7 @@ def get_ldap_connection(dn=None, password=None):
                     use_ssl=True,
                     tls=tls_configuration)
 
-    conn = Connection(server, native(dn), native(password))
+    conn = Connection(server, dn, password)
 
     if not conn.bind():
         log.error("Cannot bind to ldap server: %s ", conn.last_error)
@@ -87,8 +86,7 @@ def get_ldap_connection(dn=None, password=None):
 def group_contains_user(conn, search_base, group_filter, user_name_attr, username):
     search_filter = '(&({0}))'.format(group_filter)
 
-    if not conn.search(native(search_base), native(search_filter),
-                       attributes=[native(user_name_attr)]):
+    if not conn.search(search_base, search_filter, attributes=[user_name_attr]):
         log.warning("Unable to find group for %s %s", search_base, search_filter)
     else:
         for entry in conn.entries:
@@ -105,8 +103,7 @@ def groups_user(conn, search_base, user_filter, user_name_att, username):
         memberof_attr = configuration.conf.get("ldap", "group_member_attr")
     except Exception:
         memberof_attr = "memberOf"
-    res = conn.search(native(search_base), native(search_filter),
-                      attributes=[native(memberof_attr)])
+    res = conn.search(search_base, search_filter, attributes=[memberof_attr])
     if not res:
         log.info("Cannot find user %s", username)
         raise AuthenticationError("Invalid username or password")
@@ -210,9 +207,7 @@ class LdapUser(models.User):
 
         # todo: BASE or ONELEVEL?
 
-        res = conn.search(native(configuration.conf.get("ldap", "basedn")),
-                          native(search_filter),
-                          search_scope=native(search_scope))
+        res = conn.search(configuration.conf.get("ldap", "basedn"), search_filter, search_scope=search_scope)
 
         # todo: use list or result?
         if not res:

airflow/models/dag.py

@@ -34,7 +34,6 @@ import pendulum
 import six
 from croniter import croniter
 from dateutil.relativedelta import relativedelta
-from future.standard_library import install_aliases
 from sqlalchemy import Column, String, Boolean, Integer, Text, func, or_
 
 from airflow import configuration, settings, utils
@@ -54,8 +53,6 @@ from airflow.utils.log.logging_mixin import LoggingMixin
 from airflow.utils.sqlalchemy import UtcDateTime, Interval
 from airflow.utils.state import State
 
-install_aliases()
-
 ScheduleInterval = Union[str, timedelta, relativedelta]
 
 

airflow/www/utils.py

@@ -17,9 +17,6 @@
 # specific language governing permissions and limitations
 # under the License.
 
-from future import standard_library  # noqa
-standard_library.install_aliases()  # noqa
-
 import inspect
 import json
 import time

setup.py

@@ -323,7 +323,6 @@ def do_setup():
             'flask-swagger==0.2.13',
             'flask-wtf>=0.14.2, <0.15',
             'funcsigs==1.0.0',
-            'future>=0.16.0, <0.17',
             'gitpython>=2.0.2',
             'gunicorn>=19.5.0, <20.0',
             'iso8601>=0.1.12',