Configure Multiple OpenELB Replicas
This document describes how to configure multiple OpenELB replicas to ensure high availability in a production environment. You can skip this document if OpenELB is used in a test environment. By default, only one OpenELB replica is installed in a Kubernetes cluster.
- If all Kubernetes cluster nodes are deployed under the same router (BGP mode or Layer 2 mode), you are advised to configure at least two OpenELB replicas, which are installed on two Kubernetes cluster nodes respectively.
- If the Kubernetes cluster nodes are deployed under different leaf routers (BGP mode only), you are advised to configure at least two OpenELB replicas (one replica for one node) under each leaf router. For details, see Configure OpenELB for Multi-router Clusters.
Log in to the Kubernetes cluster and run the following command to label the Kubernetes cluster nodes where OpenELB is to be installed:
kubectl label --overwrite nodes master1 worker-p002 lb.kubesphere.io/v1alpha1=openelb
NOTEIn this example, OpenELB will be installed on master1 and worker-p002.
Run the following command to scale the number of openelb-manager Pods to 0:
kubectl scale deployment openelb-manager --replicas=0 -n openelb-system
Run the following command to edit the openelb-manager Deployment:
kubectl edit deployment openelb-manager -n openelb-system
In the openelb-manager Deployment YAML configuration, add the following fields under
nodeSelector: kubernetes.io/os: linux lb.kubesphere.io/v1alpha1: openelb
Run the following command to scale the number of openelb-manager Pods to the required number (change the number
2to the actual value):
kubectl scale deployment openelb-manager --replicas=2 -n openelb-system
Run the following command to check whether OpenELB has been installed on the required nodes.
kubectl get po -n openelb-system -o wide
It should return something like the following.
NAME READY STATUS RESTARTS AGE IP NODE NOMINATED NODE READINESS GATES openelb-admission-create-m2p52 0/1 Completed 0 49m 10.233.92.34 worker-p001 <none> <none> openelb-admission-patch-qmvnq 0/1 Completed 0 49m 10.233.96.15 worker-p002 <none> <none> openelb-manager-74c5467674-pgtmh 1/1 Running 0 19m 192.168.0.2 master1 <none> <none> openelb-manager-74c5467674-wmh5t 1/1 Running 0 19m 192.168.0.4 worker-p002 <none> <none>
- In Layer 2 mode, OpenELB uses the leader election feature of Kubernetes to ensure that only one replica responds to ARP/NDP requests.
- In BGP mode, all OpenELB replicas will respond to the BgpPeer configuration and attempt to establish a BGP connection with the peer BGP router by default. If the Kubernetes cluster nodes are deployed under different routers, you need to perform further configuration so that the OpenELB replicas establish BGP connections with the correct BGP routers. For details, see Configure OpenELB for Multi-router Clusters.
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