Envoy LB Operator [](https://circleci.com/gh/gojekfarm/envoy-lb-operator

) Envoy LB Operator is an Envoy Control Plane for kubernetes.

What

Configures Envoy as a Load balancer for a set of pods. This can be used in place of Kubernetes Service of Type LoadBalancer/Internal LoadBalancer and ClusterIP. You get control on load balancing via fine grained control plane of Envoy.

How

Envoy LB Operator discovers "Headless Services" with appropriate labels and injects them into envoy Control Plane.

Headless Services

Headless Services are type ClusterIp with clusterIP: None Here Kubernetes is hence used for discovery mechanism via dns.

Envoy Discovery of Headless Services via envoy-lb-operator control plane.

1. Add Headless services with label heritage: envoy-lb
2. Additionally in case of grpc services kubectl annotate svc/grpc-greeter envoy-lb-operator.gojektech.k8s.io/service-type=grpc

Pods behind such services will get added directly to envoy as a STRICT_DNS cluster

Why

1. This approach uses kubernetes for service discovery via headless services.
2. Uses Envoy for loadbalancer.
3. LoadBalancer is updated with new cluster by simply adding a new headless service. Operations on Envoy are minimized.

Once

kubectl create serviceaccount envoy-lb-operator kubectl create clusterrolebinding envoy-lb-operator-binding --clusterrole=view --serviceaccount=default:envoy-lb-operator

Dev

Build make build

Run Tests

make test

Build & Deploy on Monikube

make minikube-dev

Create deploys

make kube-deploy

Delete deploys

make kube-del

Install

This can be installed via a helm chart assuming you have gojektech-incubator repo. You can read about that here (https://github.com/gojektech/charts)

helm install gojektech-incubator/envoy-lb-operator --name=some-envoy-cp\

you can get the service details

kubectl describe svc/some-envoy-cp-envoy-lb-operator

This can then set the relevant values in ./examples/envoy.yaml Node ID should be appropriately set to match the config on Envoy and Operator

node:
  cluster: service_greeter
  id: id1 

This can support multiple envoy clusters. It can be configured as follows:

envoy_discovery_mapping:
  - envoy_id: "id1"
    upstream_label: "label1=val1"
    namespace: "namespace1"
  - envoy_id: "id2"
    upstream_label: "label2=val2"
    namespace: "namespace2"

All the upstreams having a given label (eg: label1=val1) will be registered to the corresponding envoy (eg: id1) in the specified namespace (eg: namespace1).

The Envoy should be pointed to the previously created service.

load_assignment:
  cluster_name: "xds_cluster"
  endpoints:
  - lb_endpoints:
      - endpoint:
          address:
            socket_address:
              address: some-cp-envoy-lb-operator
              port_value: 80
              protocol: "TCP"

Now Following will install Envoy pointing to the previously installed operator as Control plane.

helm install --name some-lb stable/envoy -f values.yaml

Where values.yaml has the overridden files.envoy.yaml value.

Envoy connection refresh

Every time the snapshot version changes, envoy connections are dropped and recreated. The following configs determine the frequency of snapshot updates.

refresh_interval_in_s determines the time interval between envoy config updates. auto_refresh_conn determines whether snaphot version should be incremented at an interval of refresh_interval_in_s irrespective of whether the routing config changes or not. If set to false, version will be incremented only when there are service updates.

envoy_discovery_mapping:
  - envoy_id: "id1"
    upstream_label: "label1=val1"
    endpoint_label: "label2=val2"
    namespace: "namespace1"

endpoint_label matches all the endpoints with the given label, and updates the snapshot when there are endpoint updates.