plugin/kubernetes: allow trimming down of cached items. (#2128)

* Convert to runtime.Object to smaller structs

This adds conversion for all the objects we want to keep in the cache.
It keeps the minimum for CoreDNS to function and throws away the rest.

The conversion:
api.Endpoints -> object.Endpoints
api.Pod       -> object.Pod
api.Serivce   -> object.Service

We needed to copy some client-go stuff to insert a conversion function
into NewIndexInformers.

Some unrelated cleanups in the watch functionality as that needed to be
touched because of the above translation of objects.

Signed-off-by: Miek Gieben <miek@miek.nl>

* Reduce test line-count

Signed-off-by: Miek Gieben <miek@miek.nl>

* ....and fix test

Signed-off-by: Miek Gieben <miek@miek.nl>

* Drop use of append

Signed-off-by: Miek Gieben <miek@miek.nl>

* cosmetic changes

Signed-off-by: Miek Gieben <miek@miek.nl>

* that was a typo

Signed-off-by: Miek Gieben <miek@miek.nl>

* re-introduce append here

We can't really use len() here because we don't know the number before
hand.

Signed-off-by: Miek Gieben <miek@miek.nl>

* comment in better place

Signed-off-by: Miek Gieben <miek@miek.nl>

* Make the timestamp a bool; thats where it is used for

Signed-off-by: Miek Gieben <miek@miek.nl>

* Set incoming object to nil

Explicataliy discard the converted object; we did a deep copy it's
not needed anymore.

Signed-off-by: Miek Gieben <miek@miek.nl>

* Per Chris's comment

Signed-off-by: Miek Gieben <miek@miek.nl>

1 files changed, 94 insertions, 0 deletions

diff --git a/plugin/kubernetes/object/object.go b/plugin/kubernetes/object/object.go
new file mode 100644
index 000000000..fb944b7ad
--- /dev/null
+++ b/plugin/kubernetes/object/object.go
@@ -0,0 +1,94 @@
+package object
+
+import (
+	"k8s.io/apimachinery/pkg/apis/meta/v1"
+	"k8s.io/apimachinery/pkg/runtime/schema"
+	"k8s.io/apimachinery/pkg/types"
+)
+
+// ToFunc converts one empty interface to another.
+type ToFunc func(interface{}) interface{}
+
+// Empty is an empty struct.
+type Empty struct{}
+
+// GetObjectKind implementss the ObjectKind interface as a noop.
+func (e *Empty) GetObjectKind() schema.ObjectKind { return schema.EmptyObjectKind }
+
+// GetGenerateName implements the metav1.Object interface.
+func (e *Empty) GetGenerateName() string { return "" }
+
+// SetGenerateName implements the metav1.Object interface.
+func (e *Empty) SetGenerateName(name string) {}
+
+// GetUID implements the metav1.Object interface.
+func (e *Empty) GetUID() types.UID { return "" }
+
+// SetUID implements the metav1.Object interface.
+func (e *Empty) SetUID(uid types.UID) {}
+
+// GetGeneration implements the metav1.Object interface.
+func (e *Empty) GetGeneration() int64 { return 0 }
+
+// SetGeneration implements the metav1.Object interface.
+func (e *Empty) SetGeneration(generation int64) {}
+
+// GetSelfLink implements the metav1.Object interface.
+func (e *Empty) GetSelfLink() string { return "" }
+
+// SetSelfLink implements the metav1.Object interface.
+func (e *Empty) SetSelfLink(selfLink string) {}
+
+// GetCreationTimestamp implements the metav1.Object interface.
+func (e *Empty) GetCreationTimestamp() v1.Time { return v1.Time{} }
+
+// SetCreationTimestamp implements the metav1.Object interface.
+func (e *Empty) SetCreationTimestamp(timestamp v1.Time) {}
+
+// GetDeletionTimestamp implements the metav1.Object interface.
+func (e *Empty) GetDeletionTimestamp() *v1.Time { return &v1.Time{} }
+
+// SetDeletionTimestamp implements the metav1.Object interface.
+func (e *Empty) SetDeletionTimestamp(timestamp *v1.Time) {}
+
+// GetDeletionGracePeriodSeconds implements the metav1.Object interface.
+func (e *Empty) GetDeletionGracePeriodSeconds() *int64 { return nil }
+
+// SetDeletionGracePeriodSeconds implements the metav1.Object interface.
+func (e *Empty) SetDeletionGracePeriodSeconds(*int64) {}
+
+// GetLabels implements the metav1.Object interface.
+func (e *Empty) GetLabels() map[string]string { return nil }
+
+// SetLabels implements the metav1.Object interface.
+func (e *Empty) SetLabels(labels map[string]string) {}
+
+// GetAnnotations implements the metav1.Object interface.
+func (e *Empty) GetAnnotations() map[string]string { return nil }
+
+// SetAnnotations implements the metav1.Object interface.
+func (e *Empty) SetAnnotations(annotations map[string]string) {}
+
+// GetInitializers implements the metav1.Object interface.
+func (e *Empty) GetInitializers() *v1.Initializers { return nil }
+
+// SetInitializers implements the metav1.Object interface.
+func (e *Empty) SetInitializers(initializers *v1.Initializers) {}
+
+// GetFinalizers implements the metav1.Object interface.
+func (e *Empty) GetFinalizers() []string { return nil }
+
+// SetFinalizers implements the metav1.Object interface.
+func (e *Empty) SetFinalizers(finalizers []string) {}
+
+// GetOwnerReferences implements the metav1.Object interface.
+func (e *Empty) GetOwnerReferences() []v1.OwnerReference { return nil }
+
+// SetOwnerReferences implements the metav1.Object interface.
+func (e *Empty) SetOwnerReferences([]v1.OwnerReference) {}
+
+// GetClusterName implements the metav1.Object interface.
+func (e *Empty) GetClusterName() string { return "" }
+
+// SetClusterName implements the metav1.Object interface.
+func (e *Empty) SetClusterName(clusterName string) {}