Make session limiter configurable

atst/utils/session_limiter.py

@@ -0,0 +1,19 @@
+from atst.domain.users import Users
+
+
+class SessionLimiter(object):
+    def __init__(self, config, session, redis):
+        self.limit_logins = config["LIMIT_CONCURRENT_SESSIONS"]
+        self.session = session
+        self.redis = redis
+
+    def on_login(self, user):
+        if not self.limit_logins:
+            return
+
+        session_id = self.session.sid
+        self._delete_session(user.last_session_id)
+        Users.update_last_session_id(user, session_id)
+
+    def _delete_session(self, session_id):
+        self.redis.delete("session:{}".format(session_id))