Fractal

Alert: Fractal and Mandelbrot are now unmaintained - architect-k8s is its official successor.
divnix is also working on a fork of the original fractal at https://github.com/divnix/Fractal.

Fractal is an experimental Nix-based framework for declarative configuration of Kubernetes clusters, used at Arctarus for configuration of infrastructure clusters and customer virtual clusters. Fractal makes use of XNLib as an extended version of the Nix standard library.

Motivation

Fractal was built out of frustration at no existing good solution existing to manage massive and elaborate Kubernetes clusters with bleeding-edge experimental infrastructure - no matter whether they're bare metal or cloud.

Axioms of Fractal

• Hermeticity, reproducibility
  • The output of a cluster configuration set should always be predictable. Random changes to upstream Helm charts shouldn't mutate configuration.
• Result caching for long-running builds
  • Developers shouldn't have to wait minutes to see their changes in action. Reducing the time of the inner development loop is one of Fractal's main goals.
• GitOps support (FluxCD, ArgoCD, etc.)
• Maximum control over building and overriding components

Architecture

Fractal defines Kubernetes clusters, configuration for which are built by a collection of Nix modules. Modules that represent an abstractable part of a cluster are referred to as components.

A typical Fractal repo consists of an opinionated directory structure:

• clusters define a subfolder per Kubernetes cluster, which lets you define important information, like the cluster name and DNS address
• components define the components that will be present in your cluster, these are typically seperated into three groups that are deployed sequentially:
  • operators, cluster operators that may be responsible for deploying features or services
  • features, cluster-wide infrastructure that supports services
  • services, the applications you run on top of your cluster
• modules define generic Nix modules that are imported and used to implement custom logic; you can, for example, define additional configuration for your clusters here
• support contains support files for build systems that are not Nix-related; for example, Jsonnet or Helm