/
service-discovery.go
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/
service-discovery.go
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package kubernetes
import (
"context"
"encoding/json"
"errors"
"fmt"
"net"
"strings"
"github.com/sourcegraph/conc/stream"
v1 "k8s.io/api/core/v1"
"k8s.io/client-go/informers"
"k8s.io/client-go/kubernetes"
"k8s.io/client-go/tools/cache"
entitiesv1 "github.com/fluxninja/aperture/api/gen/proto/go/aperture/discovery/entities/v1"
"github.com/fluxninja/aperture/pkg/k8s"
"github.com/fluxninja/aperture/pkg/log"
"github.com/fluxninja/aperture/pkg/notifiers"
"github.com/fluxninja/aperture/pkg/utils"
)
const podTrackerPrefix = "kubernetes_pod"
// serviceDiscovery is a collector that collects Kubernetes information periodically.
type serviceDiscovery struct {
ctx context.Context
cli kubernetes.Interface
informerFactory informers.SharedInformerFactory
entityEvents notifiers.EventWriter
cancel context.CancelFunc
serviceStream *stream.Stream
clusterDomain string
}
func newServiceDiscovery(
entityEvents notifiers.EventWriter,
k8sClient k8s.K8sClient,
) (*serviceDiscovery, error) {
kd := &serviceDiscovery{
cli: k8sClient.GetClientSet(),
entityEvents: entityEvents,
serviceStream: stream.New(),
}
kd.informerFactory = informers.NewSharedInformerFactory(kd.cli, 0)
kd.ctx, kd.cancel = context.WithCancel(context.Background())
return kd, nil
}
func (kd *serviceDiscovery) start(startCtx context.Context) error {
// get cluster domain
clusterDomain, err := getClusterDomain()
if err != nil {
log.Error().Err(err).Msg("Could not get cluster domain, will retry")
return err
}
kd.clusterDomain = clusterDomain
endpointsInformer := kd.informerFactory.Core().V1().Endpoints().Informer()
_, err = endpointsInformer.AddEventHandler(cache.ResourceEventHandlerFuncs{
AddFunc: kd.handleEndpointsAdd,
UpdateFunc: kd.handleEndpointsUpdate,
DeleteFunc: kd.handleEndpointsDelete,
})
if err != nil {
return err
}
serviceInformer := kd.informerFactory.Core().V1().Services().Informer()
_, err = serviceInformer.AddEventHandler(cache.ResourceEventHandlerFuncs{
AddFunc: kd.handleServiceAdd,
DeleteFunc: kd.handleServiceDelete,
})
if err != nil {
return err
}
kd.informerFactory.Start(kd.ctx.Done())
if !cache.WaitForCacheSync(startCtx.Done(), endpointsInformer.HasSynced, serviceInformer.HasSynced) {
return errors.New("timed out waiting for caches to sync")
}
log.Info().Msg("Service discovery started")
return nil
}
func (kd *serviceDiscovery) stop(stopCtx context.Context) error {
kd.cancel()
kd.serviceStream.Wait()
kd.entityEvents.Purge("")
return nil
}
// Endpoints informer handlers
func (kd *serviceDiscovery) handleEndpointsAdd(obj interface{}) {
endpoints := obj.(*v1.Endpoints)
kd.updateEndpoints(endpoints)
}
func (kd *serviceDiscovery) handleEndpointsUpdate(oldObj, newObj interface{}) {
oldEndpoints := oldObj.(*v1.Endpoints)
newEndpoints := newObj.(*v1.Endpoints)
// remove addresses that are no longer in the newEndpoints
for _, oldSubset := range oldEndpoints.Subsets {
for _, oldAddress := range oldSubset.Addresses {
found := false
for _, newSubset := range newEndpoints.Subsets {
for _, newAddress := range newSubset.Addresses {
if newAddress.TargetRef.UID == oldAddress.TargetRef.UID {
found = true
break
}
}
}
if !found {
// address is no longer in the newEndpoints, remove it
kd.removeEndpointAddress(oldAddress, oldEndpoints.Namespace, oldEndpoints.Name)
}
}
}
kd.updateEndpoints(newEndpoints)
}
func (kd *serviceDiscovery) handleEndpointsDelete(obj interface{}) {
endpoints := obj.(*v1.Endpoints)
kd.removeEndpoints(endpoints)
}
func (kd *serviceDiscovery) updateEndpoints(endpoints *v1.Endpoints) {
for _, subset := range endpoints.Subsets {
for _, address := range subset.Addresses {
if address.TargetRef == nil {
continue
}
if address.TargetRef.Kind != "Pod" {
continue
}
p := &entitiesv1.Entity{
Name: address.TargetRef.Name,
Namespace: address.TargetRef.Namespace,
Uid: string(address.TargetRef.UID),
IpAddress: address.IP,
Services: []string{kd.getService(endpoints.Namespace, endpoints.Name)},
}
if address.NodeName != nil {
p.NodeName = *address.NodeName
}
err := kd.updateEntity(p)
if err != nil {
log.Error().Err(err).Msg("Tracker could not be updated")
}
}
}
}
// Service informer handlers
func (kd *serviceDiscovery) handleServiceAdd(obj interface{}) {
service := obj.(*v1.Service)
kd.addClusterIPs(service)
}
func (kd *serviceDiscovery) handleServiceDelete(obj interface{}) {
service := obj.(*v1.Service)
kd.removeClusterIPs(service)
}
func (kd *serviceDiscovery) addClusterIPs(service *v1.Service) {
clusterIPs := getClusterIPsFromService(service)
for _, clusterIP := range clusterIPs {
p := &entitiesv1.Entity{
Name: strings.Join([]string{"ClusterIP", service.Namespace, service.Name, clusterIP}, "-"),
Namespace: service.Namespace,
Uid: clusterIP,
IpAddress: clusterIP,
Services: []string{kd.getService(service.Namespace, service.Name)},
}
err := kd.updateEntity(p)
if err != nil {
log.Error().Err(err).Msg("Tracker could not be updated")
}
}
}
func (kd *serviceDiscovery) removeClusterIPs(service *v1.Service) {
clusterIPs := getClusterIPsFromService(service)
for _, clusterIP := range clusterIPs {
kd.entityEvents.RemoveEvent(notifiers.Key(clusterIP))
}
}
// getService return the full qualified domain name of a given service.
func (kd *serviceDiscovery) getService(namespace, name string) string {
service := fmt.Sprintf("%s.%s.svc.%s", name, namespace, kd.clusterDomain)
return service
}
func (kd *serviceDiscovery) removeEndpointAddress(address v1.EndpointAddress, namespace, name string) {
updateFunc := func(oldValue []byte) (notifiers.EventType, []byte) {
if oldValue == nil {
return notifiers.Remove, nil
}
entity := &entitiesv1.Entity{}
err := json.Unmarshal(oldValue, entity)
if err != nil {
log.Error().Err(err).Msg("Could not unmarshal entity")
return notifiers.Remove, nil
}
entity.Services = utils.RemoveFromSlice(entity.Services, kd.getService(namespace, name))
if shouldRemove(entity) {
return notifiers.Remove, nil
}
bytes, err := json.Marshal(entity)
if err != nil {
log.Error().Err(err).Msg("Could not marshal entity")
return notifiers.Remove, nil
}
return notifiers.Write, bytes
}
kd.entityEvents.UpdateValue(notifiers.Key(address.TargetRef.UID), updateFunc)
}
func (kd *serviceDiscovery) removeEndpoints(endpoints *v1.Endpoints) {
for _, subset := range endpoints.Subsets {
for _, address := range subset.Addresses {
kd.removeEndpointAddress(address, endpoints.Namespace, endpoints.Name)
}
}
}
// updateEntity updates the entity in the tracker.
func (kd *serviceDiscovery) updateEntity(pod *entitiesv1.Entity) error {
updateFunc := func(oldValue []byte) (notifiers.EventType, []byte) {
var entity *entitiesv1.Entity
if oldValue == nil {
// create new entity
entity = pod
} else {
err := json.Unmarshal(oldValue, &entity)
if err != nil {
log.Error().Msgf("Error unmarshaling entity: %v", err)
return notifiers.Write, oldValue
}
for _, service := range pod.Services {
if !utils.SliceContains(entity.Services, service) {
entity.Services = append(entity.Services, service)
}
}
}
value, err := json.Marshal(entity)
if err != nil {
log.Error().Msgf("Error marshaling entity: %v", err)
return notifiers.Write, oldValue
}
return notifiers.Write, value
}
kd.entityEvents.UpdateValue(notifiers.Key(pod.Uid), updateFunc)
return nil
}
/* Helper functions */
func getClusterIPsFromService(svc *v1.Service) []string {
if svc.Spec.Type != v1.ServiceTypeClusterIP {
return nil
}
clusterIPs := svc.Spec.ClusterIPs
// remove None, "" from the list
clusterIPs = utils.RemoveFromSlice(clusterIPs, "None")
clusterIPs = utils.RemoveFromSlice(clusterIPs, "")
return clusterIPs
}
func shouldRemove(entity *entitiesv1.Entity) bool {
// once we have more informers then add additional checks here
return len(entity.Services) == 0
}
// getClusterDomain retrieves cluster domain of Kubernetes cluster we are installed on.
// It can be retrieved by looking up CNAME of kubernetes.default.svc and extracting its suffix.
func getClusterDomain() (string, error) {
apiSvc := "kubernetes.default.svc"
cname, err := net.LookupCNAME(apiSvc)
if err != nil {
return "", err
}
clusterDomain := strings.TrimPrefix(cname, apiSvc+".")
clusterDomain = strings.TrimSuffix(clusterDomain, ".")
return clusterDomain, nil
}