Many organizations are interested in running Kubernetes on a hybrid cloud setup. This often becomes a priority after a major data center outage or after receiving an unexpectedly high bill from a cloud provider. The goal is to leverage the flexibility and scalability of Kubernetes while avoiding vendor lock-in.
What is hybrid cloud
Running Kubernetes on hybrid cloud means running a single Kubernetes cluster across on-premises infrastructure and public cloud environments. Public clouds may include well-known providers such as AWS, Azure, or Google Cloud, while private clouds may include platforms such as OpenStack, Proxmox, or even bare metal servers.
Advantages of hybrid cloud Kubernetes:
- Cost efficiency: Execute baseline workloads on bare metal servers and scale using the public cloud when additional capacity is needed.
- Flexibility: Choose the best cloud provider for a specific workload based on cost or performance.
- Unified management: Manage all workloads in a single Kubernetes cluster.
- Vendor independence: Avoid being locked into a single cloud vendor.
- Repository solution: Execute repository operators directly on Kubernetes, similar to how managed repositories work in the cloud.
- Disaster recovery: Keep backup nodes in the cloud for quick failover during outages.
Challenges of running Kubernetes on hybrid cloud
While the benefits are significant, running Kubernetes on hybrid cloud is not without its challenges:
- Cloud integration: Native integration with cloud services is critical for smooth operation.
- Network: Secure and reliable connections between on-premises and cloud environments are critical.
- Latency: Minimize latency by optimizing traffic routing.
- Security: Implement strong measures to protect workloads and data across environments.
Hybrid existing solutions for Kubernetes
Kubernetes already provides several tools and capabilities for effectively managing hybrid cloud clusters:
Network settings
Networking is one of the most important aspects of a hybrid Kubernetes cluster. You must ensure:
- Secure VPN or direct connection between local and cloud networks.
- Consistent IP address and DNS resolution.
- Appropriate network policies for traffic management.
- Load balancing across on-premises and cloud environments.
Network architecture is very important for hybrid cloud Kubernetes. It is difficult to change a cluster once it is up and running.
cluster configuration
When setting up a cluster:
- Define which workloads run on-premises and which run in the cloud.
- Use node selectors/associations to control where specific Pods operate.
Control plane configuration
Kubernetes uses etcd as a database to store cluster state. It is critical to ensure that etcd remains highly available and secure. Here are some best practices:
- Use an odd number of etcd nodes: This ensures high availability and avoids split-brain situations.
- Run across multiple Availability Zones or cloud providers: Ensure low latency between nodes and choose the provider with the lowest latency.
- Regularly back up etcd data: Prevent data loss through automatic backup.
- Disaster Recovery Plan: Test and train disaster recovery plans for etcd failures.
Cloud integration
Most cloud providers offer plugins to integrate with Kubernetes. These plugins are designed to run on the cloud provider’s Kubernetes service. However, you can also run them on hybrid clusters with some modifications.
- CCM (Cloud Controller Manager) needs to change the code, please check my Modified version
- CSI (Container Storage Interface) is a standard for exposing storage systems to containerized workloads on Kubernetes. Most of these work well in a hybrid cloud setup.
- The cluster node autoscaler also requires some changes
Monitor and optimize
Monitoring tools such as Prometheus and Grafana can help track the health and performance of hybrid clusters. in addition:
- Efficiently manage resource usage using autoscalers.
- Set alerts for potential problems.
- Regularly review and optimize your cluster settings.
Running Kubernetes clusters in a hybrid environment provides flexibility and scalability, but requires careful planning and execution.
To learn more about Kubernetes on hybrid cloud, check out the following resources: