Configure envoy cluster configs using envoy filter

Config
1

Hello,

I am trying to configure envoy cluster config using envoy filter and it seems like my filter is incorrect.
I am hoping someone can help me, and if we can enhance documentation for this in the ‘Envoy Filter’ page.

Context: one of my services uses consistent hash for load-balancing.

---
apiVersion: networking.istio.io/v1alpha3
kind: DestinationRule
metadata:
  name: teletubby
spec:
  host: teletubby
  trafficPolicy:
    loadBalancer:
      consistentHash:
        httpHeaderName: r-p

For long running connections, when a pod dies, it will connect to a different pod, but when the original pod comes back online, the long running connections are connected to a different hashed pod.
To solve this, I was thinking to use close_connections_on_host_set_change which is a loadbalancer cluster config in envoy.
https://www.envoyproxy.io/docs/envoy/v1.17.0/api-v3/config/cluster/v3/cluster.proto.html?highlight=close_connections_on_host_set_change#config-cluster-v3-cluster-commonlbconfig

With this, i was expecting the istio gateway to close existing connections when hosts are added/removed from that service.

I tried to set this up by adding it as Envoy Filter.
But it seems like my understanding of configuring this filter is not correct and perhaps some missing gaps.
I assumed i am applying this to the gateway connections, and that we are patching cluster config as by default the close_connections_on_host_set_change setting is false.

My config:

---
apiVersion: networking.istio.io/v1alpha3
kind: EnvoyFilter
metadata:
  name: ingress-connections-reset-on-host-changes
  namespace: istio-system
spec:
  workloadSelector:
    labels:
      app: istio-ingressgateway
  configPatches:
  - applyTo: CLUSTER
    match:
      context: GATEWAY
      cluster: {}
    patch:
      operation: REPLACE
      filterClass: UNSPECIFIED
      value:
        common_lb_config:
          close_connections_on_host_set_change: true

I am happy to add this or similar sample in docs for ppl wanting to update cluster configs. Would soneone be able to point me in right direction?
thanks,

2

Hi Rashmi,
Are you able to get it working with the EnvoyFilter?

3

Hi,
I can get the consistent hash to work but couldn’t reset connection on host list change for which i was using the envoy filter for! :frowning: