Is rest=true a must for MongoDB's replicaSet setup?

Question

I see there are a lot of tutoirl on the internet suggest to add the rest parameter

mongod --rest --replSet myset 

Are there any side effect if I don't use them?

Answer 1

You don't need the rest interface for a replica-set.
It could be very helpful in the testing period thou.
Rest interface listens on db port +1000 and displays a lot of useful information about the nodes in replica-set, synchronization status, etc.

It it recommended to be disabled in production environment, or at least firewalled.

Answer 2

First, there is a difference between the HTTP console (which is on by default and is disabled with --nohttpinterface) and the simple REST interface, which is off by default and enabled with the --rest option, or rest=true in a config file. The official docs reflect this, see:

http://www.mongodb.org/display/DOCS/Http+Interface#HttpInterface-HTTPConsole

http://www.mongodb.org/display/DOCS/Http+Interface#HttpInterface-SimpleRESTInterface

In either case, the answer to your question is no - neither the HTTP console nor the simple REST interface is required for a replica set to function and can be disabled (or not enabled, as the case may be) as you wish without any side effects.

In terms of having a REST interface in production, you will find recommendations for a full REST interface on that page - none of the solutions are officially supported by 10gen, but sleepy mongoose is a 10gen labs project.