webhosting-operator

webhosting-operator

webhosting-operator is a simple operator developed using kubebuilder. It is built for demonstrating and evaluating the implemented sharding mechanisms for Kubernetes controllers, see Evaluating the Sharding Mechanism.

The webhosting-operator is developed in a dedicated Go module so that its dependencies don't leak into the main module which also contains the shard library. The webhosting-operator reuses the sharder components from the shard library as described in Implement Sharding in Your Controller.

For now, the webhosting-operator is kept in the same repository for simple evaluation of the project. However, it might be extracted into a dedicated repository later on if necessary.

Sample Operator Requirements

To demonstrate and evaluate the proposed sharding design, an operator is needed that fulfills the following requirements:

• it should be composed of a single controller for one (custom) resource
• in addition to watching its own resources, it needs to watch other relevant objects (e.g. owned objects) as well
  • sharding is more difficult here, so add it as a challenge
• it needs to deal with cluster-scoped objects (that are relevant for multiple namespaced objects)
  • this adds side effects (duplicated cache) which need to be taken care of

Idea / Introduction

The idea behind this operator is simple: we want to build a web hosting platform on top of Kubernetes. I.e., we want to be able to configure websites for our customers in a declarative manner. The desired state is configured via Kubernetes (custom) resources and the operator takes care to spin up websites and expose them.

There are three resources involved:

• Namespace
  • each customer project gets its own namespace
  • a project namespace is identified by the webhosting.timebertt.dev/project=true label
• Theme (API group webhosting.timebertt.dev, cluster-scoped)
  • represents an offered theme for customer websites (managed by service admin)
  • configures a font family and color for websites
• Website (API group webhosting.timebertt.dev, namespaced)
  • represents a single website a customer orders (managed by the customer in a project namespace)
  • website simply displays the website's name (static)
  • each website references exactly one theme
  • deploys and configures a simple nginx deployment
  • exposes the website via service and ingress

Setup

To test controller sharding with the webhosting-operator as an example controller, see Evaluation.