Is there an easy way to make sessions timeout in flask?

flask sessions expire once you close the browser unless you have a permanent session. You can possibly try the following:

from datetime import timedelta
from flask import session, app

@app.before_request
def make_session_permanent():
    session.permanent = True
    app.permanent_session_lifetime = timedelta(minutes=5)

By default in Flask, permanent_session_lifetime is set to 31 days.

Yes, We should set

session.permanent = True
app.permanent_session_lifetime = timedelta(minutes=5)

But I don't think it should be set at app.before_request, This will lead to set them too may times.

The permanent_session_lifetime is a Basics Configuration, so it should be set at you configure the app:

 from datetime import timedelta
 app = Flask(__name__)
 app.config['SECRET_KEY'] = 'xxxxxxxxx'
 app.config['PERMANENT_SESSION_LIFETIME'] =  timedelta(minutes=5)

The session will created for each client, seperated from other clients. So, I think the best place to set session.permanent is when you login():

@app.route('/login', methods=['GET', 'POST'])
def login():
    #After Verify the validity of username and password
    session.permanent = True

Using a slight modification on CodeGeek's answer, the decorator @before_first_request is enough to get flask to "remember" the session timeout. @before_request runs before EACH request, which is not necessary. I've tested this with different timeouts and it works.

The calls are explained here.

from datetime import timedelta
from flask import session, app

@app.before_first_request  # runs before FIRST request (only once)
def make_session_permanent():
    session.permanent = True
    app.permanent_session_lifetime = timedelta(minutes=5)