Is it possible to set up non-round robin DNS load balancing?

May 23, 2014 3.4k views
cowsun.tech
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cowsun.tech
Is it possible to set up non-round robin DNS load balancing? Desired functionality: *Note Server A is a clone of Server B Scenario 1 - No fault : [Incoming request] -> [DigitalOcean DNS ] -> [Server A responding] Scenario 2 - Server A Fault: [Incoming request] -> [DigitalOcean DNS] -> [Server A NOT responding] -> [Server B responds] Scenario 3 - Server A & Server B Fault [Me] -> [Bar] -> [Beer] *Note, yes I read this: https://www.digitalocean.com/community/articles/how-to-configure-dns-round-robin-load-balancing-for-high-availability And the load balancing section here: https://www.digitalocean.com/community/articles/dns-tips-and-tricks
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1 Answer
nickkwest May 23, 2014
You can use HAProxy for load balancing, there are articles about it here:
https://digitalocean.com/community/articles/an-introduction-to-haproxy-and-load-balancing-concepts
here:
https://digitalocean.com/community/articles/how-to-use-haproxy-to-set-up-mysql-load-balancing--3
and here:
https://digitalocean.com/community/articles/how-to-use-haproxy-as-a-layer-4-load-balancer-for-wordpress-application-servers-on-ubuntu-14-04

With a single HAProxy node, this woulds still leave a single point of failure. Since DO doesn't support floating IPs (yet) you can't scale this up to having 2 geodiverse HAProxy nodes. That said, it's still an improvement over round robin since an app node is far more likely to go down than a slim, hardened HAProxy node.

You can also use nginx for load balancing (this is quite popular these days):
https://digitalocean.com/community/articles/how-to-set-up-nginx-load-balancing

nginx will have the same issue that HAProxy does, in that you still have a single point of failure.

Since DO doesn't support floating IPs (yet), I'll mention Amazon's Route 53 which is capable of intelligent round robin, health checking destination nodes, and geo-diverse hosted DNS, it's also relatively cheap:
http://docs.aws.amazon.com/Route53/latest/DeveloperGuide/Tutorials.html

You can use Route 53 in conjunction with DO droplets. I believe DO is working on their own implementation of floating IPs to solve the super high availability problem.
How To Set Up Nginx Load Balancing
by Etel Sverdlov
This article covers how to set up a simple load balancer on a DigitalOcean droplet with nginx. The tutorial covers setting up a round robin loadbalancer that can then direct site visitors to one of a set of IPs
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