Initial k8s support in libplayground (#216)

* Initial k8s support in libplayground

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

scheduler/task/check_k8s_cluster_exposed_ports.go

@@ -0,0 +1,77 @@
+package task
+
+import (
+	"context"
+	"log"
+
+	"github.com/play-with-docker/play-with-docker/event"
+	"github.com/play-with-docker/play-with-docker/k8s"
+	"github.com/play-with-docker/play-with-docker/pwd/types"
+	meta_v1 "k8s.io/apimachinery/pkg/apis/meta/v1"
+)
+
+type checkK8sClusterExposedPortsTask struct {
+	event   event.EventApi
+	factory k8s.FactoryApi
+}
+
+var CheckK8sClusterExpoedPortsEvent event.EventType
+
+func init() {
+	CheckK8sClusterExpoedPortsEvent = event.EventType("instance k8s cluster ports")
+}
+
+func (t *checkK8sClusterExposedPortsTask) Name() string {
+	return "CheckK8sClusterPorts"
+}
+
+func NewCheckK8sClusterExposedPorts(e event.EventApi, f k8s.FactoryApi) *checkK8sClusterExposedPortsTask {
+	return &checkK8sClusterExposedPortsTask{event: e, factory: f}
+}
+
+func (c checkK8sClusterExposedPortsTask) Run(ctx context.Context, i *types.Instance) error {
+
+	kc, err := c.factory.GetKubeletForInstance(i)
+	if err != nil {
+		return err
+	}
+
+	if isManager, err := kc.IsManager(); err != nil {
+		log.Println(err)
+		return err
+	} else if !isManager {
+		return nil
+	}
+
+	k8s, err := c.factory.GetForInstance(i)
+	if err != nil {
+		log.Println(err)
+		return err
+	}
+
+	list, err := k8s.CoreV1().Services("").List(meta_v1.ListOptions{})
+	if err != nil {
+		return err
+	}
+	exposedPorts := []int{}
+
+	for _, svc := range list.Items {
+		for _, p := range svc.Spec.Ports {
+			if p.NodePort > 0 {
+				exposedPorts = append(exposedPorts, int(p.NodePort))
+			}
+		}
+	}
+
+	nodeList, err := k8s.CoreV1().Nodes().List(meta_v1.ListOptions{})
+	if err != nil {
+		return err
+	}
+	instances := []string{}
+	for _, node := range nodeList.Items {
+		instances = append(instances, node.Name)
+	}
+
+	c.event.Emit(CheckSwarmPortsEvent, i.SessionId, ClusterPorts{Manager: i.Name, Instances: instances, Ports: exposedPorts})
+	return nil
+}