feat(kuma-cp) user specified load balancer type per route

[nickolaev]

Summary

Extending the TrafficRoute to be able to specify the LoadBalancer type, reflecting Envoy's capabilities.
Supported types:

• Round-robin
• Least request - can set choice count
• Ring hash - can set hash function, min/max ring size
• Random
• Maglev

A sample Universal resource would look like this:

type: TrafficRoute
name: route-all-default
mesh: default
sources:
  - match:
      kuma.io/service: '*'
destinations:
  - match:
      kuma.io/service: '*'
conf:
  loadBalancer:
    roundRobin: {}
  split:
    - destination:
        kuma.io/service: '*'
      weight: 100

Where the loadBalancer field can have the following values

  loadBalancer:
    leastRequest:
      choiceCount: 32

  loadBalancer:
    ringHash:
      hashFunction: "MURMUR_HASH_2"
      minRingSize: 64
      maxRingSize: 1024

  loadBalancer:
    random: {}

  loadBalancer:
    maglev: {}

Issues resolved

Fix #1030

Documentation

• Link to the website documentation PR

[jakubdyszkiewicz]

some nits, looks great!

[jakubdyszkiewicz]

conf.loadBalancer.ringHash.hashFunction

[jakubdyszkiewicz]

ot -> to

[jakubdyszkiewicz]

nit: alias v1alpha1 to mesh_proto

[jakubdyszkiewicz]

(and it's feat(kuma-cp))

[lobkovilya]

I think it might be confusing that loadBalancer field is located on the top level of conf. It feels like this load balancer will be used to balance traffic across destinations, but in fact, we don't balance across the destinations, moreover, we have a NO_FALLBACK policy between these destinations.

I'd suggest renaming this top level loadBalancer to defaultLoadBalancer and have loadBalancer field for every destination:

type: TrafficRoute
name: route-all-default
mesh: default
sources:
  - match:
      kuma.io/service: '*'
destinations:
  - match:
      kuma.io/service: '*'
conf:
  defaultLoadBalancer:
    roundRobin: {}
  split:
    - destination:
        kuma.io/service: backend
        version: 1
      weight: 90
      loadBalancer: 
        maglev: {}
    - destination:
        kuma.io/service: backend
        version: 2
      weight: 5
      loadBalancer:
        random: {}
    - destination:
        kuma.io/service: backend
        version: 3
      weight: 5

What do you think about it?

[jakubdyszkiewicz]

@lobkovilya
LB is placed on cluster, how would you like to place it on individual splits?

[lobkovilya]

Sorry, I was confused by this line:

subset.Lb = route.Spec.GetConf().GetLoadBalancer()

nevermind

[nickolaev]

@Mergifyio update

[mergify]

Command update: success

Branch has been successfully updated

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