Kubernetes Multi Cluster

Multi-Cluster Kubernetes: A Practical Guide

What Is Multi-Cluster Kubernetes?

Multi-cluster Kubernetes refers to the management of multiple Kubernetes clusters, which are groups of nodes working together to orchestrate and run containerized applications. These clusters can be distributed across different data centers, regions, or cloud providers to ensure high availability, fault tolerance, and better performance.

This is part of a series of articles about Kubernetes networking.

In this article:

Kubernetes Multi-Cluster Architecture and Approaches

A Kubernetes multi-cluster architecture can be designed using different strategies, depending on the application requirements and infrastructure constraints. Here are two common approaches:

  • Replicated architecture: In this architecture, the entire application stack, including all its services and components, is deployed across multiple Kubernetes clusters. Each cluster runs a complete copy of the application, ensuring that all services are available in each cluster.
  • Split-by-service architecture: In this architecture, different parts of the application are deployed in separate Kubernetes clusters. Instead of replicating the entire application stack, each cluster is responsible for running specific services or components.

When dealing with multi-cluster Kubernetes, there are different approaches to manage and operate these clusters. Two common approaches are:

  • Kubernetes-centric: In this approach, the focus is on using Kubernetes-native tools and APIs to manage and operate multiple clusters. This approach relies on extending the Kubernetes control plane across the clusters, providing a unified management and monitoring interface.
  • Network-centric: This approach emphasizes the networking layer and focuses on connecting multiple clusters at the network level. It often uses service meshes to provide secure and reliable communication between services across different clusters.

Advantages of Multi-Cluster Kubernetes

Using multi-cluster Kubernetes provides several benefits for organizations that need to manage complex applications and infrastructure. Here are the main advantages:


Multi-cluster Kubernetes allows organizations to deploy their applications across different environments, such as on-premises data centers, private clouds, and multiple public cloud providers. This flexibility helps in reducing vendor lock-in and enables organizations to select the best infrastructure and services for their specific needs.

Availability, Scalability, and Resource Utilization

By distributing workloads across multiple Kubernetes clusters, you can achieve higher availability and redundancy, reducing the risk of a single point of failure. If one cluster goes down, the workloads can continue running on other clusters. Additionally, multi-cluster Kubernetes makes it easier to scale your applications by adding more resources and distributing the load across different regions or data centers.

Multi-cluster Kubernetes can help optimize resource utilization by balancing the workloads among clusters. This prevents resource overutilization in one cluster and ensures optimal performance. Moreover, by deploying specific services or components in separate clusters, you can allocate resources more efficiently based on the specific needs of each service.

Workload Isolation

Multi-cluster Kubernetes allows you to isolate different workloads, such as development, staging, and production environments, in separate clusters. This improves fault tolerance and reduces the risk of cascading failures. Workload isolation also enables you to enforce strict resource quotas and security policies on a per-cluster basis.

Security and Compliance

By deploying clusters in different regions or countries, you can comply with data sovereignty and regulatory requirements. This ensures that the data is stored and processed within the boundaries of a specific jurisdiction. Additionally, multi-cluster Kubernetes allows you to implement more granular security policies and access controls for each cluster, enhancing the overall security of your applications and infrastructure.

Related content: Read our guide to Kubernetes network security

Challenges of Multi-Cluster Kubernetes

While multi-cluster Kubernetes offers numerous advantages, it also introduces certain challenges that organizations need to address when managing and operating multiple clusters. Some of the key challenges include:

Configuration and management complexity
Managing multiple clusters requires maintaining consistent configurations, resource definitions, and deployment manifests across all clusters. This can increase the complexity of configuration management and the likelihood of configuration drift or inconsistencies between clusters.

Network connectivity and latency
As workloads and services are distributed across different clusters, potentially in various geographical locations, network connectivity and latency can become critical factors. Ensuring secure and reliable communication between services in different clusters, while minimizing latency, can be challenging.

Cross-cluster service discovery and load balancing
In a multi-cluster environment, services need to discover and communicate with other services across different clusters. Implementing service discovery and load balancing across clusters can be more complex compared to a single-cluster setup.

Monitoring and observability
Monitoring multiple clusters can be challenging, as organizations need to aggregate and correlate metrics, logs, and traces from all clusters to gain a holistic view of the system’s performance and health. This requires implementing centralized monitoring and observability solutions that can handle multi-cluster data.

Security and access control
With multiple clusters, managing security policies, access controls, and credentials becomes more complex. Ensuring consistent security configurations and policies across clusters, while limiting the blast radius in case of security incidents, requires careful planning and execution.

Download our guide: Networking, Security & Observability for multi-cluster Kubernetes environments

Tools for Kubernetes Multi-Cluster Management

Here are several technologies that can help organizations effectively manage Kubernetes multi-cluster implementations:

Infrastructure as Code

Infrastructure as Code (IaC) is a practice that treats infrastructure configuration and provisioning as code, allowing for automated and consistent management of infrastructure resources. IaC tools enable developers and operations teams to define, version, and deploy infrastructure components using code, making it easier to create, modify, and maintain complex environments like multi-cluster Kubernetes.

Using IaC tools for Kubernetes multi-cluster management offers several benefits:

  • Consistency: IaC helps ensure consistent configurations across multiple clusters, reducing the risk of configuration drift and human error.
  • Versioning and collaboration: IaC tools typically integrate with version control systems, allowing teams to collaborate on infrastructure changes, track modifications, and easily roll back to previous configurations if needed.
  • Automation and repeatability: IaC enables automated provisioning and deployment of infrastructure resources, making it easier to create and manage multiple Kubernetes clusters with minimal manual intervention.
  • Modularization and reuse: IaC tools support modularization, allowing teams to create reusable templates for common infrastructure components, which can be shared and reused across different clusters.

Managed Kubernetes Services

Managed Kubernetes services are offerings provided by cloud providers or third-party vendors that simplify the deployment, management, and scaling of Kubernetes clusters. These services abstract away the underlying infrastructure and operational complexities, allowing organizations to focus on deploying and managing their applications.

Managed Kubernetes services can be beneficial for multi-cluster management in several ways:

  • Simplified cluster lifecycle management: Managed services handle the provisioning, scaling, and upgrading of Kubernetes clusters, making it easier to manage multiple clusters across different environments.
  • Unified control plane: Managed services typically provide a unified control plane for managing and monitoring multiple clusters, streamlining the administration of multi-cluster environments.
  • Enhanced security and compliance: Managed Kubernetes services often include built-in security features and best practices, ensuring a secure and compliant multi-cluster setup.
  • Support and maintenance: Managed services include support from the provider, ensuring that any issues related to the Kubernetes clusters are addressed promptly.

Service Mesh

A service mesh is a dedicated infrastructure layer designed to facilitate secure, reliable, and observable communication between services in a microservices architecture. Service meshes can be particularly helpful when managing multi-cluster Kubernetes environments.

Service mesh advantages for multi-cluster Kubernetes management include:

  • Cross-cluster service discovery: Service meshes can provide service discovery capabilities across different clusters, enabling seamless communication between services even when they are distributed across multiple Kubernetes clusters.
  • Load balancing and traffic management: Service meshes can handle load balancing and traffic routing between services in different clusters, improving the reliability and performance of inter-cluster communication.
  • Enhanced observability: Service meshes provide detailed metrics, logs, and tracing information, making it easier to monitor and troubleshoot issues in a multi-cluster environment.
  • Security and access control: Service meshes can enforce security policies and access controls for communication between services across clusters, ensuring secure and compliant cross-cluster communication.

Multi-Cluster Kubernetes with Calico

Calico offers a unified, centralized solution for managing and securing multi-cluster Kubernetes environments across on-premises, hybrid, and multi-cloud infrastructures, and any Kubernetes distributions or data plane. This allows organizations to enjoy the benefits of multi-cluster Kubernetes, while addressing the associated challenges.

Key features of Calico’s multi-cluster Kubernetes solution include:

  • Any cloud, any Kubernetes distribution – Calico works with on-premises, hybrid, and multi-cloud environments, improving observability and simplifying troubleshooting and support while providing consistency across complex, distributed architectures.
  • Choice of pluggable data planes – Calico supports various data planes such as Linux, eBPF, Windows, and VPP, offering flexibility to organizations based on their specific needs.
  • Federate resources by identity and service – Calico enables consistent security and policy management across the environment by federating resources. It allows organizations to protect traffic between pods by identity, apply the same policy across multiple clusters, and apply policies to single applications or microservices spread across multiple clusters.

By using Calico, organizations can take advantage of a single pane of glass for centralized security across multi-cluster, multi-cloud, and hybrid cloud environments for their cloud-native applications. This ensures consistent application of security controls across both containers and VMs, leading to faster troubleshooting, adherence to compliance requirements, and uniform policy enforcement across different cloud providers, Kubernetes distributions, and data planes.

Next Steps:

Join our mailing list​

Get updates on blog posts, workshops, certification programs, new releases, and more!