CODEWITHSUNDEEP
node.jsexpressredis
jenkinz
jenkinz

Reputation: 139

In node, how do I detect how much time is left in a redis session?

In node using express.js, I have a redis-based session set up thusly:

// Redis session
const sessionStore = new RedisStore({
    client: getRedisClient(),
    prefix: 'bl:',
    ttl: parseInt(config.sessionTTL, 10),
    logErrors: (err) => {
        log.error('Redis session error', {
            err_message: err.message,
            err_stack: err.stack
        });
    }
});

app.use(session({
    secret: config.sessionSecret,
    store: sessionStore,
    resave: false,
    saveUninitialized: false
}));

The ttl parameter is typically set to 30 minutes, at the end of which the session dies quite nicely.

I now need to advise the user when 5 minutes or less remains of their session but can't find a way of determining when I hit that landmark.

I assumed (rather naively) the amount of time left would be stored in req.session, but when I display that it typically only shows the following:

Session {
  cookie: { path: '/', _expires: null, originalMaxAge: null, httpOnly: true },
  cookieChoiceConfirmationBannerSeen: 'seen',
  accessPage: '/decision/application-reference',
  appRef: '12345678'
}

How can I find how much time is left on my session? Should I use maxAge or expiry rather than ttl?

========= EDIT ========= Additial info: the code for getRedisClient:

const redis = require('ioredis');
const config = require('../config/config');

let client;

const getRedisClient = () => {
    if (!client) {
        client = redis.createClient({
            host: config.redisHost,
            port: config.redisPort
        });
    }
    return client;
};

module.exports = {
    getRedisClient
};

Upvotes: 1

Views: 528

Answers (1)

eol
eol

Reputation: 24565

You should be able to get the ttl of the entry itself by calling your redisClient with the corresponding key, i.e. your defined key-prefix (default sess) and the session-id. Something like this should work:

const prefix = 'bl:';
 
const redisClient = getRedisClient();

// Redis session
const sessionStore = new RedisStore({
  client: redisClient,
  prefix: 'bl:',
  ttl: parseInt(config.sessionTTL, 10),
  logErrors: (err) => {
    log.error('Redis session error', {
        err_message: err.message,
        err_stack: err.stack
    });
  }
});

app.get('/get-session-ttl', (req, res) => {    
    redisClient.ttl(`${prefix}${req.session.id}`,((err, reply) => {
        console.log("the remaining ttl is "+reply);
        res.send("...");
    }));
})

Upvotes: 1

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