Containerized deployments offer more scalability and availability improvements over traditional deployments. Even with these improvements, complex applications can quickly overwhelm containerized environments without proper management. Kubernetes helps organizations to:
- Effectively orchestrate containerized environments
- Efficiently manage the underlying resources and user demands
However, there are situations where a single Kubernetes cluster is unable to handle the application load or properly distribute the application to end-users. In such instances, multi-cluster Kubernetes solutions are ideal for distributing the work across multiple clusters.
What is a Kubernetes multi-cluster?
Kubernetes multi-cluster is an environment with multiple Kubernetes clusters. They can be configured in several ways:
- Within a single physical host
- With different multiple hosts in the same data center
- In different regions within a single cloud provider
- Utilizing multiple cloud providers and distributed across multiple regions to provide a truly global multi-cluster environment
Kubernetes multi-cluster architecture
When it comes to multi-cluster architecture, there are two considerations:
- The Kubernetes multi-cluster configuration
- The application architecture
There are primarily two methods to handle a multi-cluster Kubernetes environment:
- The Kubernetes-centric federated method
- The network-centric method
A Kubernetes-centric method uses tools like kubefed to manage multiple Kubernetes clusters from a centralized location (federated clusters). Other tools like Shipperand Admiralty can facilitate:
- Rollout strategies
- Multi-cluster orchestration
- Workload distribution
The network-centric method aims to provide a robust network to facilitate communication between different clusters. The clusters act as separate entities, yet applications can communicate with each other using a network. The network approach is based on mesh networking principles and has adapted service mesh concepts to the infrastructure. An example of this approach is:
- Linkerd service mirroring
Multi-clusters offer multi benefits
Kubernetes multi-clusters is an extensive field composed of multiple implementations and integration methods dictating multi-cluster deployments.
With all the advantages it offers for large-scale applications, it is paramount that you select the appropriate architecture for your multi-cluster environment and tool stack to manage the Kubernetes multi-cluster centrally.