[greenhatman]

You can have more than one server per monolith.

I don't think you actually understand what microservices are. You don't put a load balancer to load balance between different services. A load balancer balances trafic between servers of the same service or monolith.

Microservices mean the servers of different services run different code. A load balancer only works together with servers running the same code.

[SgtBastard]

>A load balancer only works together with servers running the same code.

Uh - what?

>A load balancer balances traffic between servers

Correct.

> of the same service or mononlith

Incorrect.

Load balancers used to work solely at Layer 4, in which case you’d be correct that any 80/443 traffic would be farmed across servers that would necessarily need to run the same code base.

But modern load balancers (NGINX et al) especially in a service mesh / Kubernetes context, balance load at endpoint level. A high traffic endpoint might have dozens of pods running on dozens of K8s hosts having traffic routes to them by their ingress controller. A low traffic endpoint’s pod might only be running on few or one (potentially different) hosts.

The load balancer internally makes these decisions.

I hope this clears up your misunderstanding.

[closeparen]

Each set of upstream hosts in nginx is a single instance of load balancing. You aren't load balancing across services, you're splitting traffic by service and then load balancing across instances of that service.

The split is inessential. You can just as easily have homogeneous backends & one big load balancing pool. Instances within that pool can even have affinity for or ownership of particular records! The ability to load balance across nodes is not, as you claimed, a particular advantage of microservices.

[greenhatman]

I don't really think of route based "load balancing" as load balancing. That's routing, or a reverse proxy. Not load balancing. Load balancing is a very specific type of reverse proxy.

The point is, if a client makes a request to a server, the response should always be the same, no matter where the load balancer sends the request to. Which means it should run the same code.

Nginx doesn't even mention route based or endpoint based load balancing in their docs. Maybe they don't consider it load balancing either.

https://www.nginx.com/resources/glossary/load-balancing/