Pylint fixes

.pylintrc

@@ -0,0 +1,2 @@
+[TYPECHECK]
+generated-members=app.logger.*

jail2ban/__init__.py

@@ -1,11 +1,16 @@
+'''
+jail2ban, a remote fail2ban action plugin using OpenBSD pf(8)
+'''
+from ipaddress import ip_address
+import re
+from subprocess import CalledProcessError
+
 from flask import Flask, request, jsonify, current_app
 from flask_httpauth import HTTPBasicAuth
 from werkzeug.security import check_password_hash
-from ipaddress import ip_address
-import re
+
 from jail2ban.pfctl import pfctl_table_op, pfctl_cfg_read, pfctl_cfg_write
 from jail2ban.auth import get_users
-from subprocess import CalledProcessError
 
 
 auth = HTTPBasicAuth()
@@ -30,11 +35,13 @@ def untaint(pattern, string):
     match = re.match(pattern, string)
     if match:
         return match.string
-    else:
-        raise ValueError(f'"{string}" is tainted')
+    raise ValueError(f'"{string}" is tainted')
 
 
 def create_app():
+    '''
+    Create wsgi application instance
+    '''
     app = Flask(__name__, instance_relative_config=True)
 
     # load the instance config, if it exists, when not testing
@@ -48,6 +55,7 @@ def create_app():
         if username in users and \
                 check_password_hash(users.get(username), password):
             return username
+        return None
 
     @app.route("/ping", methods=['GET'])
     @auth.login_required
@@ -118,21 +126,21 @@ def create_app():
         data = request.get_json()
         # name / ip
         name = untaint(PAT_NAME, data['name'])
-        ip = ip_address(data['ip'])
+        ip_addr = ip_address(data['ip'])
         if request.method == 'PUT':
-            app.logger.info(f'Add {ip} to f2b-{name}'
+            app.logger.info(f'Add {ip_addr} to f2b-{name}'
                             f' in anchor f2b-jail/{remote_user}')
             res = pfctl_table_op(f'f2b-jail/{remote_user}',
                                  table=f'f2b-{name}',
                                  operation='add',
-                                 value=str(ip))
+                                 value=str(ip_addr))
         else:  # 'DELETE':
-            app.logger.info(f'Remove {ip} from f2b-{name}'
+            app.logger.info(f'Remove {ip_addr} from f2b-{name}'
                             f' in anchor f2b-jail/{remote_user}')
             res = pfctl_table_op(f'f2b-jail/{remote_user}',
                                  table=f'f2b-{name}',
                                  operation='delete',
-                                 value=str(ip))
+                                 value=str(ip_addr))
         return jsonify({'anchor': f'f2b-jail/{remote_user}',
                         'table': f'f2b-{name}',
                         'operation': 'add' if request.method == 'PUT'