Staleness in controllers comes from an outdated view of the world inside of the controller cache. In order to provide a fast user experience, controllers typically maintain a local cache of the state of the cluster. This cache is populated by watching the Kubernetes API server for changes to objects that the controller cares about. When the controller needs to take action, it will first check its cache to see if it has the latest information. If it does not, it will then update its cache by watching the API server for changes to objects that the controller cares about. This process is known as
Kubernetes v1.36: Staleness Mitigation and Observability for Controllers… Example: expected behavior With the feature gate disabled the default fixed-interval loop , the counter increments steadily regardless of whether any node changes occurred: After 10 minutes with no node changes route controller route sync total 60 After 20 minutes, still no node changes route contr… …
… SELinux warning controller optional Kubernetes v1.36 provides a new controller within the control plane, selinux-warning-controller . This controller runs within the kube-controller-manager controller. …
… This causes unnecessary API requests to the cloud provider when there are no changes to routes. Other controllers implemented through the same library already use watch-based mechanisms, leveraging informers to avoid unnecessary API calls. …
… The changes are on by default for these controllers, and can be disabled by setting the feature gates StaleControllerConsistency to false for the specific controller you wish to disable it for. …
… For more details, see the behavioral changes introduced in beta and the upgrade considerations sections of the previous blog for graduation to beta. …
… The news is that now Cluster API can choose between immutable rollouts and in-place update extensions to perform required changes. …
… The tests: spin up an Ingress-NGINX controller spin up multiple Gateway API controllers apply Ingress resources that have implementation-specific configuration translate Ingress resources to Gateway API with ingress2gateway and apply generated manifests verify that the Gateway API controllers and t… …
… If your workload uses DRA, you must recreate the claim templates separately to match any resource changes. …
… Staleness mitigation for controllers Staleness in Kubernetes controllers is a problem that affects many controllers and can subtly affect controller behavior. …
… Gradual configuration rollouts When rolling out configuration changes, you can: Add a new drop-in file with a high numeric prefix e.g., 99-new-feature.conf Test the changes on a subset of nodes Gradually roll out to more nodes Once stable, merge changes into the base configuration Viewing the merge… …