Minor refactorings (#368)

* Split vkubelet funcitons into separate files.

* Minor re-org for cmd/census*

* refactor run loop

vkubelet/node.go

@@ -0,0 +1,129 @@
+package vkubelet
+
+import (
+	"context"
+	"strings"
+
+	"github.com/virtual-kubelet/virtual-kubelet/log"
+	"go.opencensus.io/trace"
+	corev1 "k8s.io/api/core/v1"
+	"k8s.io/apimachinery/pkg/api/errors"
+	metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
+)
+
+// registerNode registers this virtual node with the Kubernetes API.
+func (s *Server) registerNode(ctx context.Context) error {
+	ctx, span := trace.StartSpan(ctx, "registerNode")
+	defer span.End()
+
+	taints := make([]corev1.Taint, 0)
+
+	if s.taint != nil {
+		taints = append(taints, *s.taint)
+	}
+
+	node := &corev1.Node{
+		ObjectMeta: metav1.ObjectMeta{
+			Name: s.nodeName,
+			Labels: map[string]string{
+				"type":                                                    "virtual-kubelet",
+				"kubernetes.io/role":                                      "agent",
+				"beta.kubernetes.io/os":                                   strings.ToLower(s.provider.OperatingSystem()),
+				"kubernetes.io/hostname":                                  s.nodeName,
+				"alpha.service-controller.kubernetes.io/exclude-balancer": "true",
+			},
+		},
+		Spec: corev1.NodeSpec{
+			Taints: taints,
+		},
+		Status: corev1.NodeStatus{
+			NodeInfo: corev1.NodeSystemInfo{
+				OperatingSystem: s.provider.OperatingSystem(),
+				Architecture:    "amd64",
+				KubeletVersion:  "v1.11.2",
+			},
+			Capacity:        s.provider.Capacity(ctx),
+			Allocatable:     s.provider.Capacity(ctx),
+			Conditions:      s.provider.NodeConditions(ctx),
+			Addresses:       s.provider.NodeAddresses(ctx),
+			DaemonEndpoints: *s.provider.NodeDaemonEndpoints(ctx),
+		},
+	}
+	addNodeAttributes(span, node)
+	if _, err := s.k8sClient.CoreV1().Nodes().Create(node); err != nil && !errors.IsAlreadyExists(err) {
+		span.SetStatus(trace.Status{Code: trace.StatusCodeUnknown, Message: err.Error()})
+		return err
+	}
+	span.Annotate(nil, "Registered node with k8s")
+
+	log.G(ctx).Info("Registered node")
+
+	return nil
+}
+
+// updateNode updates the node status within Kubernetes with updated NodeConditions.
+func (s *Server) updateNode(ctx context.Context) {
+	ctx, span := trace.StartSpan(ctx, "updateNode")
+	defer span.End()
+
+	opts := metav1.GetOptions{}
+	n, err := s.k8sClient.CoreV1().Nodes().Get(s.nodeName, opts)
+	if err != nil && !errors.IsNotFound(err) {
+		log.G(ctx).WithError(err).Error("Failed to retrieve node")
+		span.SetStatus(trace.Status{Code: trace.StatusCodeUnknown, Message: err.Error()})
+		return
+	}
+	addNodeAttributes(span, n)
+	span.Annotate(nil, "Fetched node details from k8s")
+
+	if errors.IsNotFound(err) {
+		if err = s.registerNode(ctx); err != nil {
+			log.G(ctx).WithError(err).Error("Failed to register node")
+			span.SetStatus(trace.Status{Code: trace.StatusCodeUnknown, Message: err.Error()})
+		} else {
+			span.Annotate(nil, "Registered node in k8s")
+		}
+		return
+	}
+
+	n.ResourceVersion = "" // Blank out resource version to prevent object has been modified error
+	n.Status.Conditions = s.provider.NodeConditions(ctx)
+
+	capacity := s.provider.Capacity(ctx)
+	n.Status.Capacity = capacity
+	n.Status.Allocatable = capacity
+
+	n.Status.Addresses = s.provider.NodeAddresses(ctx)
+
+	n, err = s.k8sClient.CoreV1().Nodes().UpdateStatus(n)
+	if err != nil {
+		log.G(ctx).WithError(err).Error("Failed to update node")
+		span.SetStatus(trace.Status{Code: trace.StatusCodeUnknown, Message: err.Error()})
+		return
+	}
+}
+
+type taintsStringer []corev1.Taint
+
+func (t taintsStringer) String() string {
+	var s string
+	for _, taint := range t {
+		if s == "" {
+			s = taint.Key + "=" + taint.Value + ":" + string(taint.Effect)
+		} else {
+			s += ", " + taint.Key + "=" + taint.Value + ":" + string(taint.Effect)
+		}
+	}
+	return s
+}
+
+func addNodeAttributes(span *trace.Span, n *corev1.Node) {
+	span.AddAttributes(
+		trace.StringAttribute("UID", string(n.UID)),
+		trace.StringAttribute("name", n.Name),
+		trace.StringAttribute("cluster", n.ClusterName),
+	)
+	if span.IsRecordingEvents() {
+		span.AddAttributes(trace.StringAttribute("taints", taintsStringer(n.Spec.Taints).String()))
+	}
+}