Simple cookie-based session middleware.
A user session can be stored in two main ways with cookies: on the server or on the client. This module stores the session data on the client within a cookie, while a module like express-session stores only a session identifier on the client within a cookie and stores the session data on the server, typically in a database.
The following points can help you choose which to use:
cookie-sessiondoes not require any database / resources on the server side, though the total session data cannot exceed the browser's max cookie size.cookie-sessioncan simplify certain load-balanced scenarios.cookie-sessioncan be used to store a "light" session and include an identifier to look up a database-backed secondary store to reduce database lookups.
NOTE This module does not encrypt the session contents in the cookie, only provides
signing to prevent tampering. The client will be able to read the session data by
examining the cookie's value. Secret data should not be set in req.session without
encrypting it, or use a server-side session instead.
NOTE This module does not prevent session replay, as the expiration set is that
of the cookie only; if that is a concern of your application, you can store an expiration
date in req.session object and validate it on the sever, and implement any other logic
to extend the session as your application needs.
This is a Node.js module available through the
npm registry. Installation is done using the
npm install command:
$ npm install cookie-sessionvar cookieSession = require('cookie-session')
var express = require('express')
var app = express()
app.use(cookieSession({
name: 'session',
keys: [/* secret keys */],
// Cookie Options
maxAge: 24 * 60 * 60 * 1000 // 24 hours
}))Create a new cookie session middleware with the provided options. This middleware
will attach the property session to req, which provides an object representing
the loaded session. This session is either a new session if no valid session was
provided in the request, or a loaded session from the request.
The middleware will automatically add a Set-Cookie header to the response if the
contents of req.session were altered. Note that no Set-Cookie header will be
in the response (and thus no session created for a specific user) unless there are
contents in the session, so be sure to add something to req.session as soon as
you have identifying information to store for the session.
Cookie session accepts these properties in the options object.
The name of the cookie to set, defaults to session.
The list of keys to use to sign & verify cookie values, or a configured
Keygrip instance. Set cookies are always
signed with keys[0], while the other keys are valid for verification, allowing
for key rotation. If a Keygrip instance is provided, it can be used to
change signature parameters like the algorithm of the signature.
A string which will be used as single key if keys is not provided.
Other options are passed to cookies.get() and cookies.set() allowing you
to control security, domain, path, and signing among other settings.
The options can also contain any of the following (for the full list, see cookies module documentation:
maxAge: a number representing the milliseconds fromDate.now()for expiryexpires: aDateobject indicating the cookie's expiration date (expires at the end of session by default).path: a string indicating the path of the cookie (/by default).domain: a string indicating the domain of the cookie (no default).partitioned: a boolean indicating whether to partition the cookie in Chrome for the CHIPS Update (falseby default). If this is true, Cookies from embedded sites will be partitioned and only readable from the same top level site from which it was created.priority: a string indicating the cookie priority. This can be set to'low','medium', or'high'.sameSite: a boolean or string indicating whether the cookie is a "same site" cookie (falseby default). This can be set to'strict','lax','none', ortrue(which maps to'strict').secure: a boolean indicating whether the cookie is only to be sent over HTTPS (falseby default for HTTP,trueby default for HTTPS). If this is set totrueand Node.js is not directly over a TLS connection, be sure to read how to setup Express behind proxies or the cookie may not ever set correctly.httpOnly: a boolean indicating whether the cookie is only to be sent over HTTP(S), and not made available to client JavaScript (trueby default).signed: a boolean indicating whether the cookie is to be signed (trueby default).overwrite: a boolean indicating whether to overwrite previously set cookies of the same name (trueby default).
Represents the session for the given request.
Is true if the session has been changed during the request.
Is true if the session is new.
Determine if the session has been populated with data or is empty.
Represents the session options for the current request. These options are a shallow clone of what was provided at middleware construction and can be altered to change cookie setting behavior on a per-request basis.
To destroy a session simply set it to null:
req.session = nullSince the entire contents of the session is kept in a client-side cookie, the
session is "saved" by writing a cookie out in a Set-Cookie response header.
This is done automatically if there has been a change made to the session when
the Node.js response headers are being written to the client and the session
was not destroyed.
var cookieSession = require('cookie-session')
var express = require('express')
var app = express()
app.set('trust proxy', 1) // trust first proxy
app.use(cookieSession({
name: 'session',
keys: ['key1', 'key2']
}))
app.get('/', function (req, res, next) {
// Update views
req.session.views = (req.session.views || 0) + 1
// Write response
res.end(req.session.views + ' views')
})
app.listen(3000)var cookieSession = require('cookie-session')
var express = require('express')
var app = express()
app.set('trust proxy', 1) // trust first proxy
app.use(cookieSession({
name: 'session',
keys: ['key1', 'key2']
}))
// This allows you to set req.session.maxAge to let certain sessions
// have a different value than the default.
app.use(function (req, res, next) {
req.sessionOptions.maxAge = req.session.maxAge || req.sessionOptions.maxAge
next()
})
// ... your logic here ...This module does not send a Set-Cookie header if the contents of the session
have not changed. This means that to extend the expiration of a session in the
user's browser (in response to user activity, for example) some kind of
modification to the session needs be made.
var cookieSession = require('cookie-session')
var express = require('express')
var app = express()
app.use(cookieSession({
name: 'session',
keys: ['key1', 'key2']
}))
// Update a value in the cookie so that the set-cookie will be sent.
// Only changes every minute so that it's not sent with every request.
app.use(function (req, res, next) {
req.session.nowInMinutes = Math.floor(Date.now() / 60e3)
next()
})
// ... your logic here ...This example shows creating a custom Keygrip instance as the keys option
to provide keys and additional signature configuration.
var cookieSession = require('cookie-session')
var express = require('express')
var Keygrip = require('keygrip')
var app = express()
app.use(cookieSession({
name: 'session',
keys: new Keygrip(['key1', 'key2'], 'SHA384', 'base64')
}))
// ... your logic here ...Because the entire session object is encoded and stored in a cookie, it is possible to exceed the maximum cookie size limits on different browsers. The RFC6265 specification recommends that a browser SHOULD allow
At least 4096 bytes per cookie (as measured by the sum of the length of the cookie's name, value, and attributes)
In practice this limit differs slightly across browsers. See a list of browser limits here. As a rule of thumb don't exceed 4093 bytes per domain.
If your session object is large enough to exceed a browser limit when encoded, in most cases the browser will refuse to store the cookie. This will cause the following requests from the browser to either a) not have any session information or b) use old session information that was small enough to not exceed the cookie limit.
If you find your session object is hitting these limits, it is best to consider if data in your session should be loaded from a database on the server instead of transmitted to/from the browser with every request. Or move to an alternative session strategy
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