I have tried twice. Following these instructions :
Next, launch the NodeBB instance, so it links with the just-launched Redis instance.
docker run --name my-forum-nodebb --link my-forum-redis:redis -p 80:80 -p 443:443 -p 4567:4567 -P -t -i nodebb/docker:ubuntu
You will be asked to configure your NodeBB instance, as no config file was found. Simply press enter for all settings except Redis hostname, which should be redis as it is linked using the –linked parameter to our Redis instance, and the administrator username, e-mail and password.
The default port of nodebb is 4567. Ports 80, and 443 have also been exposed for your convenience. You can keep the default nodebb port or change it.
And it failed both times
8/12 09:16  - error: Error: Redis connection to 127.0.0.1:6379 failed - connect ECO NNREFUSED
at RedisClient.flush_and_error (/opt/nodebb/node_modules/redis/index.js:142:13)
at RedisClient.on_error (/opt/nodebb/node_modules/redis/index.js:180:10)
at Socket.<anonymous> (/opt/nodebb/node_modules/redis/index.js:95:14)
at Socket.EventEmitter.emit (events.js:95:17)
at process._tickCallback (node.js:415:13)
8/12 09:16  - warn: NodeBB Setup Aborted. Redis connection to 127.0.0.1:6379 failed - connect ECONNREFUSED
EDIT: it doesn't even ask for hostname or username. I am using ubuntu 14 64bit vps