Initial k8s support in libplayground (#216)

* Initial k8s support in libplayground

* Make tasks never give up + custom event for k8s cluster status

k8s/local_cached_factory.go

@@ -0,0 +1,124 @@
+package k8s
+
+import (
+	"fmt"
+	"log"
+	"sync"
+	"time"
+
+	"github.com/play-with-docker/play-with-docker/pwd/types"
+	"github.com/play-with-docker/play-with-docker/storage"
+	metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
+	"k8s.io/client-go/kubernetes"
+)
+
+type localCachedFactory struct {
+	rw              sync.Mutex
+	irw             sync.Mutex
+	sessionClient   *kubernetes.Clientset
+	instanceClients map[string]*instanceEntry
+	storage         storage.StorageApi
+}
+
+type instanceEntry struct {
+	rw            sync.Mutex
+	client        *kubernetes.Clientset
+	kubeletClient *kubeletClient
+}
+
+func (f *localCachedFactory) GetForInstance(instance *types.Instance) (*kubernetes.Clientset, error) {
+	key := instance.Name
+
+	f.irw.Lock()
+	c, found := f.instanceClients[key]
+	if !found {
+		c := &instanceEntry{}
+		f.instanceClients[key] = c
+	}
+	c = f.instanceClients[key]
+	f.irw.Unlock()
+
+	c.rw.Lock()
+	defer c.rw.Unlock()
+
+	if c.client == nil {
+		kc, err := NewClient(instance, "l2:443")
+		if err != nil {
+			return nil, err
+		}
+		c.client = kc
+	}
+
+	err := f.check(func() error {
+		_, err := c.client.CoreV1().Pods("").List(metav1.ListOptions{})
+		return err
+	})
+	if err != nil {
+		return nil, err
+	}
+
+	return c.client, nil
+}
+
+func (f *localCachedFactory) GetKubeletForInstance(instance *types.Instance) (*kubeletClient, error) {
+	key := instance.Name
+
+	f.irw.Lock()
+	c, found := f.instanceClients[key]
+	if !found {
+		c := &instanceEntry{}
+		f.instanceClients[key] = c
+	}
+	c = f.instanceClients[key]
+	f.irw.Unlock()
+
+	c.rw.Lock()
+	defer c.rw.Unlock()
+
+	if c.kubeletClient == nil {
+		kc, err := NewKubeletClient(instance, "l2:443")
+		if err != nil {
+			return nil, err
+		}
+		c.kubeletClient = kc
+	}
+
+	err := f.check(func() error {
+		r, err := c.kubeletClient.Get("/pods")
+		if err != nil {
+			return err
+		}
+		defer r.Body.Close()
+		return nil
+	})
+	if err != nil {
+		return nil, err
+	}
+
+	return c.kubeletClient, nil
+}
+
+func (f *localCachedFactory) check(fn func() error) error {
+	ok := false
+	for i := 0; i < 5; i++ {
+		err := fn()
+		if err != nil {
+			log.Printf("Connection to k8s api has failed, maybe instance is not ready yet, sleeping and retrying in 1 second. Try #%d. Got: %v\n", i+1, err)
+			time.Sleep(time.Second)
+			continue
+		}
+		ok = true
+		break
+	}
+	if !ok {
+		return fmt.Errorf("Connection to k8s api was not established.")
+	}
+	return nil
+}
+
+func NewLocalCachedFactory(s storage.StorageApi) *localCachedFactory {
+	return &localCachedFactory{
+		instanceClients: make(map[string]*instanceEntry),
+		storage:         s,
+	}
+}