Cluster API, Immutability, and the Future of Kubernetes Infrastructure

Why immutability is important Speed Operations at scale Security Stability How to achieve immutability in Kubernetes A few examples Rolling upgrades Remediating unhealthy Machines Avoiding unnecessary rollouts Wrapping up References Discover more from VMware Cloud Foundation (VCF) Blog Related Articles Cluster API, Immutability, and the Future of Kubernetes Infrastructure Where Logic and Creativity Meet: Libby Shen on Building Sustainable Solutions with VMware Cloud Foundation VMware Data Services Manager – DBaaS Solution for Private Cloud Since the Cluster API 1.12 release announcement [1], I keep getting questions about immutability in Kubernetes. Amid this new wave of interest, what stands out is how the Kubernetes community is looking at this topic from a different perspective than in the past. Today, adopters are less focused on immutability at the individual node level and more interested in how immutable principles apply when operating an entire fleet of clusters. This is the fundamental reason why the Cluster API project exists, and in this blog I’d like to share my perspective as a Cluster API maintainer. The importance of immutability derives from the benefits this approach provides to the applications that are running on top of Kubernetes. Based on my experience, the most important benefits that Kubernetes adopters derive from immutability are the following. In modern IT, speed is paramount. For example, you need speed when scaling up your infrastructure to handle spikes in user requests; you need speed when performing blue/green deployments or when scaling down the infrastructure to keep application costs under control or to free up resources for other tasks. Speed is also crucial when handling maintenance operations that should fit into a limited time window, or when handling any kind of disruption within the wide spectrum that goes from issues to a single application instance to when you are dealing with an entire region down. Immutability is a foundational enabler to achieve speed in all the above scenarios and even more. It is thanks to immutability that you can have tools for spinning up ten identical Pods in milliseconds, tools to create new clones of Machines hosting Kubernetes nodes in seconds, or to spin up a new, fully operational Kubernetes cluster in minutes. From a certain point of view, IT operations nowadays sit at the intersection between scale and speed.