SpinKube at a glance

spin-operator

Spin Operator is a Kubernetes operator which empowers platform engineers to deploy Spin applications as custom resources to their Kubernetes clusters. Spin Operator provides an elegant solution for platform engineers looking to improve efficiency without compromising on performance while maintaining workload portability.

Why Spin Operator?

By bringing the power of the Spin framework to Kubernetes clusters, Spin Operator provides application developers and platform engineers with the best of both worlds. For developers, this means easily building portable serverless functions that leverage the power and performance of Wasm via the Spin developer tool. For platform engineers, this means using idiomatic Kubernetes primitives (secrets, autoscaling, etc.) and tooling to manage these workloads at scale in a production environment, improving their overall operational efficiency.

How Does Spin Operator Work?

Built with the kubebuilder framework, Spin Operator is a Kubernetes operator. Kubernetes operators are used to extend Kubernetes automation to new objects, defined as custom resources, without modifying the Kubernetes API. The Spin Operator is composed of two main components:

• A controller that defines and manages Wasm workloads on k8s.
• The “SpinApps” Custom Resource Definition (CRD).

SpinApps CRDs can be composed manually or generated automatically from an existing Spin application using the spin kube scaffold command. The former approach lends itself well to CI/CD systems, whereas the latter is a better fit for local testing as part of a local developer workflow.

Once an application deployment begins, Spin Operator handles scheduling the workload on the appropriate nodes (thanks to the Runtime Class Manager, previously known as Kwasm) and managing the resource’s lifecycle. There is no need to fetch the containerd-shim-spin binary or mutate node labels. This is all managed via the Runtime Class Manager, which you will install as a dependency when setting up Spin Operator.

containerd-shim-spin

The containerd-shim-spin is a containerd shim implementation for Spin, which enables running Spin workloads on Kubernetes via runwasi. This means that by installing this shim onto Kubernetes nodes, we can add a runtime class to Kubernetes and schedule Spin workloads on those nodes. Your Spin apps can act just like container workloads!

The containerd-shim-spin is specifically designed to execute applications built with Spin (a developer tool for building and running serverless Wasm applications). The shim ensures that Wasm workloads can be managed effectively within a Kubernetes environment, leveraging containerd’s capabilities.

In a Kubernetes cluster, specific nodes can be bootstrapped with Wasm runtimes and labeled accordingly to facilitate the scheduling of Wasm workloads. RuntimeClasses in Kubernetes are used to schedule Pods to specific nodes and target specific runtimes. By defining a RuntimeClass with the appropriate NodeSelector and handler, Kubernetes can direct Wasm workloads to nodes equipped with the necessary Wasm runtimes and ensure they are executed with the correct runtime handler.

Overall, the Containerd Shim Spin represents a significant advancement in integrating Wasm workloads into Kubernetes clusters, enhancing the versatility and capabilities of container orchestration.

runtime-class-manager

The Runtime Class Manager, also known as the Containerd Shim Lifecycle Operator, is designed to automate and manage the lifecycle of containerd shims in a Kubernetes environment. This includes tasks like installation, update, removal, and configuration of shims, reducing manual errors and improving reliability in managing WebAssembly (Wasm) workloads and other containerd extensions.

The Runtime Class Manager provides a robust and production-ready solution for installing, updating, and removing shims, as well as managing node labels and runtime classes in a Kubernetes environment.

By automating these processes, the runtime-class-manager enhances reliability, reduces human error, and simplifies the deployment and management of containerd shims in Kubernetes clusters.

spin-plugin-kube

The Kubernetes plugin for Spin is designed to enhance Spin by enabling the execution of Wasm modules directly within a Kubernetes cluster. Specifically a tool designed for Kubernetes integration with the Spin command-line interface. This plugin works by integrating with containerd shims, allowing Kubernetes to manage and run Wasm workloads in a way similar to traditional container workloads.

The Kubernetes plugin for Spin allows developers to use the Spin command-line interface for deploying Spin applications; it provides a seamless workflow for building, pushing, deploying, and managing Spin applications in a Kubernetes environment. It includes commands for scaffolding new components as Kubernetes manifests, and deploying and retrieving information about Spin applications running in Kubernetes. This plugin is an essential tool for developers looking to streamline their Spin application deployment on Kubernetes platforms.