Active-active Kubernetes architecture

How to setup an active-active architecture between two Kubernetes clusters

Overview

Active-active replication between Kubernetes clusters is a strategy to ensure high availability and disaster recovery for applications. In this setup, multiple Kubernetes clusters, typically located in different geographical regions, run identical copies of an application simultaneously.

Prerequisites

  • Install Astronetes Resiliency Operator.
  • Create a namespace where to store the secrets and run the synchronization between clusters.

Setup

Import the first cluster

Import the first Kubernetes cluster as described in details here:

  1. Save the kubeconfig file as cluster-1-kubeconfig.yaml.

    Import the kubeconfig file as secret:

    kubectl create secret generic cluster-1-kubeconfig --from-file=kubeconfig.yaml=cluster-1-kubeconfig.yaml

  2. Create the KubernetesCluster resource manifest cluster-1.yaml:

    apiVersion: assets.astronetes.io/v1alpha1
kind: KubernetesCluster
metadata:
  name: cluster-1
spec:
  secretName: cluster-1-kubeconfig

    Deploy the resource with the following command:

    kubectl create -f cluster-1.yaml

Import the second cluster

Import the first Kubernetes cluster as described in details here:

  1. Save the kubeconfig file as cluster-2-kubeconfig.yaml.

    Import the kubeconfig file as secret:

    kubectl create secret generic cluster-2-kubeconfig --from-file=kubeconfig.yaml=cluster-2-kubeconfig.yaml

  2. Create the KubernetesCluster resource manifest cluster-2.yaml:

    apiVersion: assets.astronetes.io/v1alpha1
kind: KubernetesCluster
metadata:
  name: cluster-2
spec:
  secretName: cluster-2-kubeconfig

    Deploy the resource with the following command:

    kubectl create -f cluster-2.yaml

Synchronize the clusters

Create the configuration manifest to synchronize the clusters according to the full documentation is provided at Configure kubernetes-to-kubernetes.

In the following examples there is a minimal configuration to synchronize namespaces labeled with sync=true:

  1. Save the configuration file as livesync.yaml with the following content:
apiVersion: automation.astronetes.io/v1alpha1
kind: LiveSynchronization
metadata:
  name: livesync-dev-active-active
spec:
  plugin: kubernetes-to-kubernetes
  config:
    sourceName: cluster-1
    destinationName: cluster-2
    globalSelector:
      namespaceSelector:
        labelSelector:
          matchLabels:
            sync: true
    observability:
      enabled: true
    options:
      dryRun: false
    selectors:
    - objectSelector:
        labelSelector:
          matchLabels:
            sync: true
      target:
        group: ""
        resources:
        - namespaces
        version: v1
    - target:
        group: ""
        resources:
        - services
        - secrets
        - configmaps
        - serviceaccounts
        version: v1
    - target:
        group: apps
        resources:
        - deployments
        version: v1
    - target:
        group: rbac.authorization.k8s.io
        resources:
        - clusterroles
        - rolebindings
        version: v1
    - target:
        group: networking.k8s.io
        resources:
        - ingresses
        version: v1
  suspend: false

  1. Apply the configuration:

    kubectl apply -f livesync.yaml

Operations

Pause the synchronization

The synchronization process can be paused with the following command:

kubectl patch livesynchronization active-active -p '{"spec":{"suspend":true}}' --type=merge

Resume the synchronization

The synchronization process can be paused with the following command:

kubectl patch livesynchronization active-active -p '{"spec":{"suspend":false}}' --type=merge