Sync Gateway Load Balancing

Mobile Sync Gateway
1

Hi all,

In a configuration of N couchbase server nodes does it make sense for also have N sync gateways (one on each server node) and have a load balancer distribute requests to them? And by that I don’t mean send all requests to one sync gateway till it’s unreachable and then switch to another one, but, rather route to all of them equally.

Thank you.

2

@nkonstas

To ensure high availability of Sync Gateway in production it’s a good idea to deploy multiple Sync Gateway instances and use a reverse proxy/load balancer to distribute requests across the instances.

There is some documentation on configuring nginx as a reverse proxy/load balancer for use with Sync Gateway.

3

@nkonstas Andy is correct about the benefits of using a load balancer to distribute load across a cluster of SG nodes.

A few additional thoughts on your suggestion of deploying one Sync Gateway per Couchbase Server node:

  • There usually isn’t a 1-to-1 correlation between the required number of Couchbase Server nodes, and Sync Gateway nodes.
  • It’s generally not recommended to deploy Sync Gateway and Couchbase Server to the same nodes in a production environment. There are exceptions, but generally they are deployed to different nodes, for a few reasons:
    • Sync Gateway needs to be internet-facing, and Couchbase Server generally shouldn’t be.
    • Having Sync Gateway and Couchbase Server compete for resources (memory, CPU) under load can amplify the impact of the load.
4

@andy @adamf thank you both for your feedback.

In our setup the Couchbase Servers and the SGs are on a private LAN (non-internet facing). All internet traffic goes through our reverse proxy / load balancer.

I totally understand the additional resource load - I’ll keep an eye on that and if performance degrades I’ll move the SGs on separate servers.