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, 162 insertions, 0 deletions

diff --git a/plugin/kubernetes/object/endpoint.go b/plugin/kubernetes/object/endpoint.go
new file mode 100644
index 000000000..b8531f050
--- /dev/null
+++ b/plugin/kubernetes/object/endpoint.go
@@ -0,0 +1,162 @@
+package object
+
+import (
+	api "k8s.io/api/core/v1"
+	"k8s.io/apimachinery/pkg/runtime"
+)
+
+// Endpoints is a stripped down api.Endpoints with only the items we need for CoreDNS.
+type Endpoints struct {
+	Version   string
+	Name      string
+	Namespace string
+	Index     string
+	IndexIP   []string
+	Subsets   []EndpointSubset
+
+	*Empty
+}
+
+// EndpointSubset is a group of addresses with a common set of ports. The
+// expanded set of endpoints is the Cartesian product of Addresses x Ports.
+type EndpointSubset struct {
+	Addresses []EndpointAddress
+	Ports     []EndpointPort
+}
+
+// EndpointAddress is a tuple that describes single IP address.
+type EndpointAddress struct {
+	IP            string
+	Hostname      string
+	NodeName      string
+	TargetRefName string
+}
+
+// EndpointPort is a tuple that describes a single port.
+type EndpointPort struct {
+	Port     int32
+	Name     string
+	Protocol string
+}
+
+// EndpointsKey return a string using for the index.
+func EndpointsKey(name, namespace string) string { return name + "." + namespace }
+
+// ToEndpoints converts an api.Service to a *Service.
+func ToEndpoints(obj interface{}) interface{} {
+	end, ok := obj.(*api.Endpoints)
+	if !ok {
+		return nil
+	}
+
+	e := &Endpoints{
+		Version:   end.GetResourceVersion(),
+		Name:      end.GetName(),
+		Namespace: end.GetNamespace(),
+		Index:     EndpointsKey(end.GetName(), end.GetNamespace()),
+		Subsets:   make([]EndpointSubset, len(end.Subsets)),
+	}
+	for i, eps := range end.Subsets {
+		sub := EndpointSubset{
+			Addresses: make([]EndpointAddress, len(eps.Addresses)),
+		}
+		if len(eps.Ports) == 0 {
+			// Add sentinal if there are no ports.
+			sub.Ports = []EndpointPort{{Port: -1}}
+		} else {
+			sub.Ports = make([]EndpointPort, len(eps.Ports))
+		}
+
+		for j, a := range eps.Addresses {
+			ea := EndpointAddress{IP: a.IP, Hostname: a.Hostname}
+			if a.NodeName != nil {
+				ea.NodeName = *a.NodeName
+			}
+			if a.TargetRef != nil {
+				ea.TargetRefName = a.TargetRef.Name
+			}
+			sub.Addresses[j] = ea
+		}
+
+		for k, p := range eps.Ports {
+			ep := EndpointPort{Port: p.Port, Name: p.Name, Protocol: string(p.Protocol)}
+			sub.Ports[k] = ep
+		}
+
+		e.Subsets[i] = sub
+	}
+
+	for _, eps := range end.Subsets {
+		for _, a := range eps.Addresses {
+			e.IndexIP = append(e.IndexIP, a.IP)
+		}
+	}
+
+	*end = api.Endpoints{}
+
+	return e
+}
+
+// CopyWithoutSubsets copies e, without the subsets.
+func (e *Endpoints) CopyWithoutSubsets() *Endpoints {
+	e1 := &Endpoints{
+		Version:   e.Version,
+		Name:      e.Name,
+		Namespace: e.Namespace,
+		Index:     e.Index,
+		IndexIP:   make([]string, len(e.IndexIP)),
+	}
+	copy(e1.IndexIP, e.IndexIP)
+	return e1
+}
+
+var _ runtime.Object = &Endpoints{}
+
+// DeepCopyObject implements the ObjectKind interface.
+func (e *Endpoints) DeepCopyObject() runtime.Object {
+	e1 := &Endpoints{
+		Version:   e.Version,
+		Name:      e.Name,
+		Namespace: e.Namespace,
+		Index:     e.Index,
+		IndexIP:   make([]string, len(e.IndexIP)),
+		Subsets:   make([]EndpointSubset, len(e.Subsets)),
+	}
+	copy(e1.IndexIP, e.IndexIP)
+
+	for i, eps := range e.Subsets {
+		sub := EndpointSubset{
+			Addresses: make([]EndpointAddress, len(eps.Addresses)),
+			Ports:     make([]EndpointPort, len(eps.Ports)),
+		}
+		for j, a := range eps.Addresses {
+			ea := EndpointAddress{IP: a.IP, Hostname: a.Hostname, NodeName: a.NodeName, TargetRefName: a.TargetRefName}
+			sub.Addresses[j] = ea
+		}
+		for k, p := range eps.Ports {
+			ep := EndpointPort{Port: p.Port, Name: p.Name, Protocol: p.Protocol}
+			sub.Ports[k] = ep
+		}
+
+		e1.Subsets[i] = sub
+	}
+	return e1
+}
+
+// GetNamespace implements the metav1.Object interface.
+func (e *Endpoints) GetNamespace() string { return e.Namespace }
+
+// SetNamespace implements the metav1.Object interface.
+func (e *Endpoints) SetNamespace(namespace string) {}
+
+// GetName implements the metav1.Object interface.
+func (e *Endpoints) GetName() string { return e.Name }
+
+// SetName implements the metav1.Object interface.
+func (e *Endpoints) SetName(name string) {}
+
+// GetResourceVersion implements the metav1.Object interface.
+func (e *Endpoints) GetResourceVersion() string { return e.Version }
+
+// SetResourceVersion implements the metav1.Object interface.
+func (e *Endpoints) SetResourceVersion(version string) {}