mc-router/server/k8s.go

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package server
import (
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"context"
"fmt"
"net"
"strconv"
"strings"
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"sync"
"github.com/pkg/errors"
"github.com/sirupsen/logrus"
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apps "k8s.io/api/apps/v1"
autoscaling "k8s.io/api/autoscaling/v1"
core "k8s.io/api/core/v1"
meta "k8s.io/apimachinery/pkg/apis/meta/v1"
"k8s.io/apimachinery/pkg/fields"
"k8s.io/client-go/kubernetes"
"k8s.io/client-go/rest"
"k8s.io/client-go/tools/cache"
"k8s.io/client-go/tools/clientcmd"
)
const (
AnnotationExternalServerName = "mc-router.itzg.me/externalServerName"
AnnotationDefaultServer = "mc-router.itzg.me/defaultServer"
)
type IK8sWatcher interface {
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StartWithConfig(kubeConfigFile string, autoScaleUp bool) error
StartInCluster(autoScaleUp bool) error
Stop()
}
var K8sWatcher IK8sWatcher = &k8sWatcherImpl{}
type k8sWatcherImpl struct {
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sync.RWMutex
// The key in mappings is a Service, and the value the StatefulSet name
mappings map[string]string
clientset *kubernetes.Clientset
stop chan struct{}
}
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func (w *k8sWatcherImpl) StartInCluster(autoScaleUp bool) error {
config, err := rest.InClusterConfig()
if err != nil {
return errors.Wrap(err, "Unable to load in-cluster config")
}
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return w.startWithLoadedConfig(config, autoScaleUp)
}
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func (w *k8sWatcherImpl) StartWithConfig(kubeConfigFile string, autoScaleUp bool) error {
config, err := clientcmd.BuildConfigFromFlags("", kubeConfigFile)
if err != nil {
return errors.Wrap(err, "Could not load kube config file")
}
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return w.startWithLoadedConfig(config, autoScaleUp)
}
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func (w *k8sWatcherImpl) startWithLoadedConfig(config *rest.Config, autoScaleUp bool) error {
w.stop = make(chan struct{}, 1)
clientset, err := kubernetes.NewForConfig(config)
if err != nil {
return errors.Wrap(err, "Could not create kube clientset")
}
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w.clientset = clientset
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_, serviceController := cache.NewInformer(
cache.NewListWatchFromClient(
clientset.CoreV1().RESTClient(),
string(core.ResourceServices),
core.NamespaceAll,
fields.Everything(),
),
&core.Service{},
0,
cache.ResourceEventHandlerFuncs{
AddFunc: w.handleAdd,
DeleteFunc: w.handleDelete,
UpdateFunc: w.handleUpdate,
},
)
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go serviceController.Run(w.stop)
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w.mappings = make(map[string]string)
if autoScaleUp {
_, statefulSetController := cache.NewInformer(
cache.NewListWatchFromClient(
clientset.AppsV1().RESTClient(),
"statefulSets",
core.NamespaceAll,
fields.Everything(),
),
&apps.StatefulSet{},
0,
cache.ResourceEventHandlerFuncs{
AddFunc: func(obj interface{}) {
statefulSet, ok := obj.(*apps.StatefulSet)
if !ok {
return
}
w.RLock()
defer w.RUnlock()
w.mappings[statefulSet.Spec.ServiceName] = statefulSet.Name
},
DeleteFunc: func(obj interface{}) {
statefulSet, ok := obj.(*apps.StatefulSet)
if !ok {
return
}
w.RLock()
defer w.RUnlock()
delete(w.mappings, statefulSet.Spec.ServiceName)
},
UpdateFunc: func(oldObj, newObj interface{}) {
oldStatefulSet, ok := oldObj.(*apps.StatefulSet)
if !ok {
return
}
newStatefulSet, ok := newObj.(*apps.StatefulSet)
if !ok {
return
}
w.RLock()
defer w.RUnlock()
delete(w.mappings, oldStatefulSet.Spec.ServiceName)
w.mappings[newStatefulSet.Spec.ServiceName] = newStatefulSet.Name
},
},
)
go statefulSetController.Run(w.stop)
}
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logrus.Info("Monitoring Kubernetes for Minecraft services")
return nil
}
// oldObj and newObj are expected to be *v1.Service
func (w *k8sWatcherImpl) handleUpdate(oldObj interface{}, newObj interface{}) {
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for _, oldRoutableService := range w.extractRoutableServices(oldObj) {
logrus.WithFields(logrus.Fields{
"old": oldRoutableService,
}).Debug("UPDATE")
if oldRoutableService.externalServiceName != "" {
Routes.DeleteMapping(oldRoutableService.externalServiceName)
}
}
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for _, newRoutableService := range w.extractRoutableServices(newObj) {
logrus.WithFields(logrus.Fields{
"new": newRoutableService,
}).Debug("UPDATE")
if newRoutableService.externalServiceName != "" {
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Routes.CreateMapping(newRoutableService.externalServiceName, newRoutableService.containerEndpoint, newRoutableService.autoScaleUp)
} else {
Routes.SetDefaultRoute(newRoutableService.containerEndpoint)
}
}
}
// obj is expected to be a *v1.Service
func (w *k8sWatcherImpl) handleDelete(obj interface{}) {
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routableServices := w.extractRoutableServices(obj)
for _, routableService := range routableServices {
if routableService != nil {
logrus.WithField("routableService", routableService).Debug("DELETE")
if routableService.externalServiceName != "" {
Routes.DeleteMapping(routableService.externalServiceName)
} else {
Routes.SetDefaultRoute("")
}
}
}
}
// obj is expected to be a *v1.Service
func (w *k8sWatcherImpl) handleAdd(obj interface{}) {
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routableServices := w.extractRoutableServices(obj)
for _, routableService := range routableServices {
if routableService != nil {
logrus.WithField("routableService", routableService).Debug("ADD")
if routableService.externalServiceName != "" {
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Routes.CreateMapping(routableService.externalServiceName, routableService.containerEndpoint, routableService.autoScaleUp)
} else {
Routes.SetDefaultRoute(routableService.containerEndpoint)
}
}
}
}
func (w *k8sWatcherImpl) Stop() {
if w.stop != nil {
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close(w.stop)
}
}
type routableService struct {
externalServiceName string
containerEndpoint string
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autoScaleUp func(ctx context.Context) error
}
// obj is expected to be a *v1.Service
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func (w *k8sWatcherImpl) extractRoutableServices(obj interface{}) []*routableService {
service, ok := obj.(*core.Service)
if !ok {
return nil
}
routableServices := make([]*routableService, 0)
if externalServiceName, exists := service.Annotations[AnnotationExternalServerName]; exists {
serviceNames := strings.Split(externalServiceName, ",")
for _, serviceName := range serviceNames {
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routableServices = append(routableServices, w.buildDetails(service, serviceName))
}
return routableServices
} else if _, exists := service.Annotations[AnnotationDefaultServer]; exists {
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return []*routableService{w.buildDetails(service, "")}
}
return nil
}
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func (w *k8sWatcherImpl) buildDetails(service *core.Service, externalServiceName string) *routableService {
clusterIp := service.Spec.ClusterIP
port := "25565"
for _, p := range service.Spec.Ports {
if p.Name == "mc-router" || p.Name == "minecraft" {
port = strconv.Itoa(int(p.Port))
}
}
rs := &routableService{
externalServiceName: externalServiceName,
containerEndpoint: net.JoinHostPort(clusterIp, port),
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autoScaleUp: w.buildScaleUpFunction(service),
}
return rs
}
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func (w *k8sWatcherImpl) buildScaleUpFunction(service *core.Service) func(ctx context.Context) error {
return func(ctx context.Context) error {
serviceName := service.Name
if statefulSetName, exists := w.mappings[serviceName]; exists {
if scale, err := w.clientset.AppsV1().StatefulSets(service.Namespace).GetScale(ctx, statefulSetName, meta.GetOptions{}); err == nil {
replicas := scale.Status.Replicas
logrus.WithFields(logrus.Fields{
"service": serviceName,
"statefulSet": statefulSetName,
"replicas": replicas,
}).Debug("StatefulSet of Service Replicas")
if replicas == 0 {
if _, err := w.clientset.AppsV1().StatefulSets(service.Namespace).UpdateScale(ctx, statefulSetName, &autoscaling.Scale{
ObjectMeta: meta.ObjectMeta{
Name: scale.Name,
Namespace: scale.Namespace,
UID: scale.UID,
ResourceVersion: scale.ResourceVersion,
},
Spec: autoscaling.ScaleSpec{Replicas: 1}}, meta.UpdateOptions{},
); err == nil {
logrus.WithFields(logrus.Fields{
"service": serviceName,
"statefulSet": statefulSetName,
"replicas": replicas,
}).Info("StatefulSet Replicas Autoscaled from 0 to 1 (wake up)")
} else {
return errors.Wrap(err, "UpdateScale for Replicas=1 failed for StatefulSet: "+statefulSetName)
}
}
} else {
return fmt.Errorf("GetScale failed for StatefulSet %s: %w", statefulSetName, err)
}
}
return nil
}
}