Redis Sessions

This is a Node.js module to keep sessions in a Redis datastore and add some useful methods.

The main purpose of this module is to generalize sessions across application server platforms. We use nginx reverse proxy to route parts of a website to a Node.js server and other parts could be Python, Ruby, .net, PHP, Coldfusion or Java servers. You can then use rest-sessions to access the same sessions on all app servers via a simple REST interface.

If you use Express check out https://www.npmjs.com/package/connect-redis-sessions for a ready to use middleware.

Installation

npm install redis-sessions

Basics

• Every session belongs to an app (e.g. webapp, app_cust123).
• create: A session is created by supplying the app and an id (usually the unique id of the user). A token will be returned.
• get: A session is queried with the app and token. This will refresh the ttl (timeout) of a session.
• set: Additional data (key/value) can be stored in the session.
• kill: A session can be killed with the app and token.
• killall: All sessions of an app can be killed.

Additional methods

• activity: Get the amount of active sessions of an app within the last n seconds.
• soid: Get all sessions of a single id.
• killsoid: Kill all sessions that belong to a single id. E.g. log out user123 on all devices.
• soapp: Get an array of all sessions of an app which were active within the last n seconds.
• Automatic cleanup of old sessions.

Performance

With Redis running on the same machine as the test script (run via npm test) on a 2017 iMac:

• Creates 1000 sessions in around 95ms.
• Gets those 1000 sessions and validates them in around 80ms.
• Removes those 1000 sessions in 8ms.

Cache (optional setting)

Note: If you want to use the cachetime option you must not supply the client option.

Modern apps might also use a lot of requests while a user is active. This results in a lot of Redis requests to look up sessions. What's faster than an in-memory cache in Redis? An in-memory cache right in your app! When you enable caching you can speed up session lookups by a lot. Consider the following before you enable it:

How does the cache work

• The reply to the get() method will be cached for the time specified in the cachetime option.
• Every set() or kill* method will flush the cache.
• The idle and r keys that will be returned will not change for cached sessions.

What would be a good value for the cachetime option?

If your sessions last for 24h and the average user-session is 20m. You might as well set the cachetime to around 30m. Consider the size of your session object that has to be kept in memory. Setting the cachetime lower is ok. Because after all it just takes a quick Redis request to fill your cache again.

Use via REST

See rest-sessions.

Use in Node.js

Initialize redis-sessions

RedisSessions = require("redis-sessions");
//
// Parameters for RedisSession:
//
// e.g. rs = new RedisSession({host:"192.168.0.20"});
//
// `port`: *optional* Default: `6379`. The Redis port.
// `host`, *optional* Default: `127.0.0.1`. The Redis host.
// `options`, *optional* Default: {}. Additional options. See: https://github.com/mranney/node_redis#rediscreateclientport-host-options
// `namespace`: *optional* Default: `rs`. The namespace prefix for all Redis keys used by this module.
// `wipe`: *optional* Default: `600`. The interval in seconds after which expired sessions are wiped. Only values `0` or greater than `10` allowed. Set to `0` to disable.
// `client`: *optional* An external RedisClient object which will be used for the connection.
// `cachetime`: *optional*  Default: `0`. Number of seconds to cache sessions in memory. Can only be used if no `client` is supplied. See the "Cache" section.
rs = new RedisSessions();

rsapp = "myapp";

Create a session

Parameters:

• app (String) The app id (namespace) for this session.
• id (String) The user id of this user. Note: There can be multiple sessions for the same user id. If the user uses multiple client devices.
• ip (String) IP address of the user. This is used to show all ips from which the user is logged in.
• ttl (Number) optional The "Time-To-Live" for the session in seconds. Default: 7200.
• d (Object) optional Additional data to set for this sessions. (see the "set" method). Default: {}
• no_resave (Boolean) optional If set to true the session will not be refreshed on session use. Instead it will run out exactly after the defined ttl. Default: false

// Set a session for `user1001`

rs.create({
  app: rsapp,
  id: "user1001",
  ip: "192.168.22.58",
  ttl: 3600,
  d: { 
    foo: "bar",
    unread_msgs: 34
  }
  },
  function(err, resp) {
    // resp should be something like 
    // {token: "r30kKwv3sA6ExrJ9OmLSm4Wo3nt9MQA1yG94wn6ByFbNrVWhcwAyOM7Zhfxqh8fe"}
  });

Notes:

• You might want to store this token in a cookie / localStorage / sessionStorage.
• If you use Express check out https://www.npmjs.com/package/connect-redis-sessions.
• As long as the ttl isn't reached this token can be used to get the session object for this user.
• Remember that a user (user1001 in this case) might have other sessions.
• If you want to limit the number of sessions a user might have you can use the soid (sessions of id) method to find other sessions of this user or the killsoid (Kill sessions of id) method to kill his other sessions first.

Update and add some more data to an existing session

rs.set({
  app: rsapp,
  token: "r30kKwv3sA6ExrJ9OmLSm4Wo3nt9MQA1yG94wn6ByFbNrVWhcwAyOM7Zhfxqh8fe",
  d: {
    "unread_msgs": 12,
    "last_action": "/read/news",
    "birthday": "2013-08-13"
  }},
  function(err, resp) {
    /*
    resp contains the session with the new values:

    {  
      "id":"user1001",
      "r": 1,
      "w": 2,
      "idle": 1,
      "ttl": 7200, 
      "d":
        {
          "foo": "bar",
          "unread_msgs": 12,
          "last_action": "/read/news",
          "birthday": "2013-08-13"
        }
    }
    */  
  });

Note: The key foo that we didn't supply in the set command will not be touched. See Set/Update/Delete details for details on how to remove keys.

Get a session for a token

rs.get({
  app: rsapp,
  token: "r30kKwv3sA6ExrJ9OmLSm4Wo3nt9MQA1yG94wn6ByFbNrVWhcwAyOM7Zhfxqh8fe"},
  function(err, resp) {
    /*
    resp contains the session:

    {  
      "id":"user1001",
      "r": 2,  // The number of reads on this token
      "w": 2,  // The number of writes on this token
      "idle": 21,  // The idle time in seconds.
      "ttl": 7200, // Timeout after 7200 seconds idle time
      "d":
         {
          "foo": "bar",
          "unread_msgs": 12,
          "last_action": "/read/news",
          "birthday": "2013-08-13"
        }
    }

    */
  });

Set/Update/Delete

Set/Update/Delete parameters by supplying app, token and some data d.
The d object contains a simple key/value list where values
can be string, number, boolean or null.
To remove keys set them to null, keys that are not supplied will not be touched.

rs.set({
  app: rsapp,
  token: "r30kKwv3sA6ExrJ9OmLSm4Wo3nt9MQA1yG94wn6ByFbNrVWhcwAyOM7Zhfxqh8fe",
  d: {
      "unread_msgs": null
      "last_action": "/read/msg/2121"
  }},
  function(err, resp) {
    /*
    resp contains the session with modified values:

    {  
      "id":"user1001",
      "r": 2,
      "w": 3,
      "idle": 1,
      "ttl": 7200, 
      "d":
        {
          "last_action": "/read/msg/2121",
          "birthday": "2013-08-13",
          "foo": "bar"
        }
    }
    */  
  });

Kill

Kill a single session by supplying app and token:

rs.kill({
  app: rsapp,
  token: "r30kKwv3sA6ExrJ9OmLSm4Wo3nt9MQA1yG94wn6ByFbNrVWhcwAyOM7Zhfxqh8fe"},
  function(err, resp) {
    /*
    resp contains the result:

    {kill: 1}
    */  
  });

Note: If {kill: 0} is returned the session was not found.

Activity

Query the amount of active session within the last 10 minutes (600 seconds). Note: Multiple sessions from the same user id will be counted as one.

rs.activity({
  app: rsapp,
  dt: 600},
  function(err, resp) {
    /*
    resp contains the activity:

    {activity: 12}
    */  
  });

Sessions of App

Get all sessions of an app there were active within the last 10 minutes (600 seconds).

rs.soapp({
  app: rsapp,
  dt: 600},
  function(err, resp) {
    /*
    resp contains the sessions:

    { sessions: 
       [ { id: 'someuser123',
           r: 1,
           w: 1,
           ttl: 30,
           idle: 0,
           ip: '127.0.0.2'
         },
         { id: 'anotheruser456',
           r: 4,
           w: 2,
           ttl: 7200,
      	   idle: 24,
           ip: '127.0.0.1' }
        ] 
    }
    */  
  });

Sessions of Id

Get all sessions within an app that belong to a single id. This would be all sessions of a single user in case he is logged in on different browsers / devices.

rs.soid({
  app: rsapp,
  id: "bulkuser_999"},
  function(err, resp) {
    /*
    resp contains the sessions:

    { sessions: 
       [ { id: 'bulkuser_999',
           r: 1,
           w: 1,
           ttl: 30,
           idle: 0,
           ip: '127.0.0.2' },
         { id: 'bulkuser_999',
           r: 1,
           w: 1,
           ttl: 7200,
           idle: 0,
           ip: '127.0.0.1' }
        ] 
    }
    */  
  });

Kill all sessions of an id

Kill all sessions of an id within an app:

rs.killsoid({app: rsapp, id: 'bulkuser_999'},
  function(err, resp) {
    /*
    resp contains the result:

    {kill: 2} // The amount of sessions that were killed
    */  
  });

Killall

Kill all sessions of an app:

rs.killall({app: rsapp},
  function(err, resp) {
    /*
    resp contains the result:

    {kill: 12} // The amount of sessions that were killed
    */  
  });

Ping

Ping the redis server

rs.ping(function(err, resp) {
    /*
    resp contains the result:

    "PONG"
    */  
});

CHANGELOG

See https://github.com/smrchy/redis-sessions/blob/master/CHANGELOG.md

More Node.js and Redis projects?

Check out my projects which are based on Node.js and Redis as a datastore:

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• Guaranteed delivery of a message to exactly one recipient within a messages visibility timeout.
• No security: Like memcached. Only for internal use in trusted environments.
• Similar to Amazon SQS (with some differences)
• Optional RESTful interface via REST-rsmq
• and more...

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• Maintains order of tagged items
• Unions and intersections while maintaining the order
• Counters for each tag
• Fast paging over results with limit and offset
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The MIT License (MIT)

Copyright © 2013 Patrick Liess, http://www.tcs.de

Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the “Software”), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED “AS IS”, WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.