Question

Does AWS support weighted load balancing? From what I see, Elastic Load Balancer only supports round-robin load balancing.

The easiest thing that I can do is to put a load balancer like Nginx in front of it, like:

upstream backend  {

  server backend1.example.com weight=1;

  server backend2.example.com weight=2;

  server backend3.example.com weight=4;

}

Here, out of these requests, one will go to backend1, two will go to backebd2 and so on, it will work but for that, I need to set up a server with Nginx. If AWS would directly support weighted load balancing that would be easier.

Answer 1

As per the documentation of how Elastic Load Balancing Works,

With a Classic Load Balancer, the load balancer node that receives the request selects a registered instance using the round-robin routing algorithm for TCP listeners and the least outstanding requests routing algorithm for HTTP and HTTPS listeners.

With an Application Load Balancer, the load balancer node that receives the request evaluates the listener rules in priority order to determine which rule to apply, and then selects a target from the target group for the rule action using the round-robin routing algorithm. Routing is performed independently for each target group, even when a target is registered with multiple target groups.

The Elastic Load Balancing does not support weighted round-robin, where you specify the weights. Rather you can use Amazon Route53 with a weighted Routing Policy.

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