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 LiveSynchronization.

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: active-active
spec:
  plugin: kubernetes-objects-to-kubernetes
  suspend: false
  config:
    sourceName: cluster-1
    destinationName: cluster-2
    replication:
      resources:
        - group: apps
          version: v1
          resource: deployments
          filters:
            namespaceSelector:
              matchLabels:
                sync: "true"
        - group: ""
          version: v1
          resource: services
          filters:
            namespaceSelector:
              matchLabels:
                sync: "true"
        - group: ""
          version: v1
          resource: secrets
          filters:
            namespaceSelector:
              matchLabels:
                sync: "true"
        - group: "rbac.authorization.k8s.io"
          version: v1
          resource: roles
          filters:
            namespaceSelector:
              matchLabels:
                sync: "true"
        - group: "rbac.authorization.k8s.io"
          version: v1
          resource: rolebindings
          filters:
            namespaceSelector:
              matchLabels:
                sync: "true"
        - group: ""
          version: v1
          resource: serviceaccounts
          filters:
            namespaceSelector:
              matchLabels:
                sync: "true"
            nameSelector:
              excludeRegex:
                - "^(default|deployer|builder)$"
        - group: "networking.k8s.io"
          version: v1
          resource: ingresses
          filters:
            namespaceSelector:
              matchLabels:
                sync: "true"

  2. 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