Conflict errors during updates should not be propagated to controller-runtime: allow customizing which errors to ignore/requeue #663
Description
Problem statement
When controllers try to update resources in cluster users see errors like the one below when the object in cache is not up to date and the update causes a conflict:
{
"level": "error",
"ts": "2025-11-29T12:10:20.594+0100",
"logger": "APIGateway",
"msg": "unable to update status",
"controller": "apigateway",
"controllerGroup": "gateway-operator.konghq.com",
"controllerKind": "APIGateway",
"APIGateway": {
"name": "apigateway-1",
"namespace": "default"
},
"namespace": "default",
"name": "apigateway-1",
"reconcileID": "520b8d74-3196-452f-8891-4cd65fdd0166",
"resourceType": "gateway-operator.konghq.com/v1alpha1, Kind=APIGateway",
"error": "Operation cannot be fulfilled on apigateways.gateway-operator.konghq.com \"apigateway-1\": the object has been modified; please apply your changes to the latest version and try again",
"stacktrace": "reconciler.io/runtime/reconcilers.(*ResourceReconciler[...]).reconcileOuter
/Users/USER/.gvm/pkgsets/go1.25.3/global/pkg/mod/reconciler.io/runtime@v0.24.1/reconcilers/resource.go:379\nreconciler.io/runtime/reconcilers.(*ResourceReconciler[...]).Reconcile
/Users/USER/.gvm/pkgsets/go1.25.3/global/pkg/mod/reconciler.io/runtime@v0.24.1/reconcilers/resource.go:302\nsigs.k8s.io/controller-runtime/pkg/internal/controller.(*Controller[...]).Reconcile
/Users/USER/.gvm/pkgsets/go1.25.3/global/pkg/mod/sigs.k8s.io/controller-runtime@v0.22.4/pkg/internal/controller/controller.go:216\nsigs.k8s.io/controller-runtime/pkg/internal/controller.(*Controller[...]).reconcileHandler
/Users/USER/.gvm/pkgsets/go1.25.3/global/pkg/mod/sigs.k8s.io/controller-runtime@v0.22.4/pkg/internal/controller/controller.go:461\nsigs.k8s.io/controller-runtime/pkg/internal/controller.(*Controller[...]).processNextWorkItem
/Users/USER/.gvm/pkgsets/go1.25.3/global/pkg/mod/sigs.k8s.io/controller-runtime@v0.22.4/pkg/internal/controller/controller.go:421\nsigs.k8s.io/controller-runtime/pkg/internal/controller.(*Controller[...]).Start.func1.1
/Users/USER/.gvm/pkgsets/go1.25.3/global/pkg/mod/sigs.k8s.io/controller-runtime@v0.22.4/pkg/internal/controller/controller.go:296"
}
These types of errors should not be user facing and controllers should be able to requeue the request and retry if there's a conflict.
Proposed solution
- Allow customization of ignored error types/values/matching with provided predicate functions
k8s.io/apimachineryprovides a lot of predicate functions for matching errors types like e.g.IsConflict
- Just change the update error handling to not propagate the error on conflicts.