controller-filtered-cache

README

controller-filtered-cache

A tool for customizing Kubernetes controller cache, using labels as filters to list and watch resources.

Background

When an operator watches, lists or gets a Kubernetes resource type, the operator will store all the resources from this kind into its cache.

This will cause if there are a huge number of this kind of resource in the cluster, the operator will consume a large number of computing resources on the caching the Kubernetes resource that it won't use.

This controller-filtered-cache provides an implement for the operator to add a label selector to the operator cache. It will only store the resources with a specific label, which helps in reducing cache, memory footprint and CPU requirements.

It supports the native kubernetes resources from GroupVersions: corev1, appsv1, batchv1, certificatesv1beta1, networkingv1, rbacv1 and storagev1.

How to use controller-filtered-cache

How to create filtered cache

Limitation

1. The kubernetes selector doesn't support OR logic: For each kubernetes object, it only supports using one string as a selector for LabelSelector and FieldSelector respectively. It can't cache a resource from two different selectors. For example, users can't cache secrets with labels app1 or app2.