Sentinel: If you subscribe after connection established, you error.

[evantahler]

Consider the folowing:

var Redis = require('ioredis');

var config = {
  options: {
    name: 'mymsater',
    db: 10,
    sentinels: [
      { host: '127.0.0.1', port: 26379 },
    ]
  }
};

var pub = Redis.createClient(null, null, config.options);
var sub = Redis.createClient(null, null, config.options);

pub.on('error', function(err){ console.log(err); });
sub.on('error', function(err){ console.log(err); });

pub.on('connect', function(){
  console.log('PUB connected');
});

sub.on('connect', function(){
  console.log('SUB connected');

  sub.subscribe('channel', function(error){
    if(error){ console.log(error); }

    sub.on('message', function(channel, message){
      console.log('[%s]: %s', channel, message);
    })

    pub.publish('channel', 'hello');
  })
});

If you wait until after the connection even to subscribe the following uncaught promise rejection is fired:

Unhandled rejection Error: Connection in subscriber mode, only subscriber commands may be used
    at Redis.sendCommand (/Users/evantahler/Dropbox/Projects/actionhero/node_modules/ioredis/lib/redis.js:500:20)
    at Redis.selectBuffer (/Users/evantahler/Dropbox/Projects/actionhero/node_modules/ioredis/lib/commander.js:117:17)
    at /Users/evantahler/Dropbox/Projects/actionhero/node_modules/ioredis/lib/redis/event_handler.js:184:12
    at /Users/evantahler/Dropbox/Projects/actionhero/node_modules/ioredis/lib/redis/event_handler.js:35:39
    at /Users/evantahler/Dropbox/Projects/actionhero/node_modules/ioredis/lib/redis.js:392:7
    at tryCatcher (/Users/evantahler/Dropbox/Projects/actionhero/node_modules/ioredis/node_modules/bluebird/js/main/util.js:26:23)
    at Promise.successAdapter (/Users/evantahler/Dropbox/Projects/actionhero/node_modules/ioredis/node_modules/bluebird/js/main/nodeify.js:23:30)
    at Promise._settlePromiseAt (/Users/evantahler/Dropbox/Projects/actionhero/node_modules/ioredis/node_modules/bluebird/js/main/promise.js:579:21)
    at Promise._settlePromises (/Users/evantahler/Dropbox/Projects/actionhero/node_modules/ioredis/node_modules/bluebird/js/main/promise.js:697:14)
    at Async._drainQueue (/Users/evantahler/Dropbox/Projects/actionhero/node_modules/ioredis/node_modules/bluebird/js/main/async.js:123:16)
    at Async._drainQueues (/Users/evantahler/Dropbox/Projects/actionhero/node_modules/ioredis/node_modules/bluebird/js/main/async.js:133:10)
    at Immediate.Async.drainQueues [as _onImmediate] (/Users/evantahler/Dropbox/Projects/actionhero/node_modules/ioredis/node_modules/bluebird/js/main/async.js:15:14)
    at processImmediate [as _immediateCallback] (timers.js:383:17)

This only seems to happen when sentinels are in use

[evantahler]

Oh, I should point out that while the rejection occurs, the message is still received:

> node test.js
PUB connected
SUB connected
Unhandled rejection Error: Connection in subscriber mode, only subscriber commands may be used
    at Redis.sendCommand (/Users/evantahler/Dropbox/Projects/actionhero/node_modules/ioredis/lib/redis.js:500:20)
    at Redis.selectBuffer (/Users/evantahler/Dropbox/Projects/actionhero/node_modules/ioredis/lib/commander.js:117:17)
    at /Users/evantahler/Dropbox/Projects/actionhero/node_modules/ioredis/lib/redis/event_handler.js:184:12
    at /Users/evantahler/Dropbox/Projects/actionhero/node_modules/ioredis/lib/redis/event_handler.js:35:39
    at /Users/evantahler/Dropbox/Projects/actionhero/node_modules/ioredis/lib/redis.js:392:7
    at tryCatcher (/Users/evantahler/Dropbox/Projects/actionhero/node_modules/ioredis/node_modules/bluebird/js/main/util.js:26:23)
    at Promise.successAdapter (/Users/evantahler/Dropbox/Projects/actionhero/node_modules/ioredis/node_modules/bluebird/js/main/nodeify.js:23:30)
    at Promise._settlePromiseAt (/Users/evantahler/Dropbox/Projects/actionhero/node_modules/ioredis/node_modules/bluebird/js/main/promise.js:579:21)
    at Promise._settlePromises (/Users/evantahler/Dropbox/Projects/actionhero/node_modules/ioredis/node_modules/bluebird/js/main/promise.js:697:14)
    at Async._drainQueue (/Users/evantahler/Dropbox/Projects/actionhero/node_modules/ioredis/node_modules/bluebird/js/main/async.js:123:16)
    at Async._drainQueues (/Users/evantahler/Dropbox/Projects/actionhero/node_modules/ioredis/node_modules/bluebird/js/main/async.js:133:10)
    at Immediate.Async.drainQueues [as _onImmediate] (/Users/evantahler/Dropbox/Projects/actionhero/node_modules/ioredis/node_modules/bluebird/js/main/async.js:15:14)
    at processImmediate [as _immediateCallback] (timers.js:383:17)
[channel]: hello

[luin]

Thank you for the feedback! This issue is related with db option instead of sentinel. The following code can reproduce the error:

var redis = new Redis({ db: 10 });
redis.on('connect', function () {
  redis.subscribe('anychannel');
});

The error is because ioredis sends the SELECT command to switch to db 10 on the ready event. In most cases that would not cause any problem because commands sent after the connect event and before the ready event will be added to the offline queue and will be resent after the ready event.

However, pub/sub commands (SUBSCRIBE, PSUBSCRIBE and UNSUBSCRIBE etc) are special that ioredis allows them to be sent to Redis before the ready event. So when we sends SELECT command on the ready event, the connection has been in the subscribe mode and Redis will reject the SELECT command.

[luin]

Release in 1.15.1 🚀

[evantahler]

Thanks for the quick patch!

[seunlanlege]

@luin getting this same error with this code

[luin]

@seunlanlege This issue has been resolved, so there may be another issue. Could you enable debug mode (DEBUG=ioredis:* node yourapp.js) and post the logs here?

[seunlanlege]

@luin here are the logs

[luin]

@seunlanlege What's the constructor argument of Redis? And what's the version of Redis server? Please enable the showFriendlyErrorStack option to see which command cause the exception (new Redis({showFriendlyErrorStack: true})).

[AVVS]

I think its a problem with the code. Redis.config is issued without await, command cant complete before .subscribe, connection is then moved to subscriber mode and cant finish it

ie I'm pretty sure if you do

await Redis.config()

and only then subscribe - you should be good