Add node provider interfaace (#526)

This starts the work of having a `NodeProvider` which is responsible for providing node details. It splits the responsibilities of node management off to a new controller. The primary change here is to add the framework pieces for node management and move the VK CLI to use this new controller. It also adds support for node leases where available. This can be enabled via the command line (disabled by default), but may fall back if we find that leaess aren't supported on the cluster.
2019-03-25 15:02:40 -07:00
parent 9e245f3737
commit 10430f0b7f
34 changed files with 4939 additions and 101 deletions
--- a/vkubelet/node.go
+++ b/vkubelet/node.go
@@ -2,113 +2,395 @@ package vkubelet

 import (
 	"context"
-	"strings"
+	"time"

 	"github.com/cpuguy83/strongerrors/status/ocstatus"
+	pkgerrors "github.com/pkg/errors"
 	"github.com/virtual-kubelet/virtual-kubelet/log"
+	"github.com/virtual-kubelet/virtual-kubelet/providers"
 	"github.com/virtual-kubelet/virtual-kubelet/trace"
-	"github.com/virtual-kubelet/virtual-kubelet/version"
+	coord "k8s.io/api/coordination/v1beta1"
 	corev1 "k8s.io/api/core/v1"
 	"k8s.io/apimachinery/pkg/api/errors"
 	metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
+	"k8s.io/client-go/kubernetes/typed/coordination/v1beta1"
+	v1 "k8s.io/client-go/kubernetes/typed/core/v1"
 )

-var (
-	// vkVersion is a concatenation of the Kubernetes version the VK is built against, the string "vk" and the VK release version.
-	// TODO @pires revisit after VK 1.0 is released as agreed in https://github.com/virtual-kubelet/virtual-kubelet/pull/446#issuecomment-448423176.
-	vkVersion = strings.Join([]string{"v1.13.1", "vk", version.Version}, "-")
+// NewNode creates a new node.
+// This does not have any side-effects on the system or kubernetes.
+//
+// Use the node's `Run` method to register and run the loops to update the node
+// in Kubernetes.
+func NewNode(p providers.NodeProvider, node *corev1.Node, leases v1beta1.LeaseInterface, nodes v1.NodeInterface, opts ...NodeOpt) (*Node, error) {
+	n := &Node{p: p, n: node, leases: leases, nodes: nodes}
+	for _, o := range opts {
+		if err := o(n); err != nil {
+			return nil, pkgerrors.Wrap(err, "error applying node option")
+		}
+	}
+	return n, nil
+}
+
+// NodeOpt are the functional options used for configuring a node
+type NodeOpt func(*Node) error
+
+// WithNodeDisableLease forces node leases to be disabled and to only update
+// using node status
+// Note that this will force status updates to occur on the ping interval frequency
+func WithNodeDisableLease(v bool) NodeOpt {
+	return func(n *Node) error {
+		n.disableLease = v
+		return nil
+	}
+}
+
+// WithNodePingInterval sets the inteval for checking node status
+func WithNodePingInterval(d time.Duration) NodeOpt {
+	return func(n *Node) error {
+		n.pingInterval = d
+		return nil
+	}
+}
+
+// WithNodeStatusUpdateInterval sets the interval for updating node status
+// This is only used when leases are supported and only for updating the actual
+// node status, not the node lease.
+func WithNodeStatusUpdateInterval(d time.Duration) NodeOpt {
+	return func(n *Node) error {
+		n.statusInterval = d
+		return nil
+	}
+}
+
+// WithNodeLease sets the base node lease to use.
+// If a lease time is set, it will be ignored.
+func WithNodeLease(l *coord.Lease) NodeOpt {
+	return func(n *Node) error {
+		n.lease = l
+		return nil
+	}
+}
+
+// Node deals with creating and managing a node object in Kubernetes.
+// It can register a node with Kubernetes and periodically update its status.
+type Node struct {
+	p providers.NodeProvider
+	n *corev1.Node
+
+	leases v1beta1.LeaseInterface
+	nodes  v1.NodeInterface
+
+	disableLease   bool
+	pingInterval   time.Duration
+	statusInterval time.Duration
+	lease          *coord.Lease
+	chStatusUpdate chan *corev1.Node
+}
+
+// The default intervals used for lease and status updates.
+const (
+	DefaultPingInterval         = 5 * time.Second
+	DefaultStatusUpdateInterval = 1 * time.Minute
 )

-// 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)
+// Run registers the node in kubernetes and starts loops for updating the node
+// status in Kubernetes.
+//
+// The node status must be updated periodically in Kubertnetes to keep the node
+// active. Newer versions of Kubernetes support node leases, which are
+// essentially light weight pings. Older versions of Kubernetes require updating
+// the node status periodically.
+//
+// If Kubernetes supports node leases this will use leases with a much slower
+// node status update (because some things still expect the node to be updated
+// periodically), otherwise it will only use node status update with the configured
+// ping interval.
+func (n *Node) Run(ctx context.Context) error {
+	if n.pingInterval == time.Duration(0) {
+		n.pingInterval = DefaultPingInterval
+	}
+	if n.statusInterval == time.Duration(0) {
+		n.statusInterval = DefaultStatusUpdateInterval
 	}

-	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:  vkVersion,
-			},
-			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),
-		},
+	if err := n.updateStatus(ctx); err != nil {
+		return pkgerrors.Wrap(err, "error registering node with kubernetes")
 	}
-	ctx = addNodeAttributes(ctx, span, node)
-	if _, err := s.k8sClient.CoreV1().Nodes().Create(node); err != nil && !errors.IsAlreadyExists(err) {
-		span.SetStatus(ocstatus.FromError(err))
-		return err
+	log.G(ctx).Info("Created node")
+
+	n.chStatusUpdate = make(chan *corev1.Node)
+	n.p.NotifyNodeStatus(ctx, func(node *corev1.Node) {
+		n.chStatusUpdate <- node
+	})
+
+	if !n.disableLease {
+		n.lease = newLease(n.lease)
+		setLeaseAttrs(n.lease, n.n, n.pingInterval*5)
+
+		l, err := ensureLease(ctx, n.leases, n.lease)
+		if err != nil {
+			if errors.IsNotFound(err) {
+				n.disableLease = true
+			} else {
+				return pkgerrors.Wrap(err, "error creating node lease")
+			}
+		}
+		log.G(ctx).Debug("Created node lease")
+
+		n.lease = l
 	}

-	log.G(ctx).Info("Registered node")
+	if n.disableLease {
+		log.G(ctx).Info("Node leases not supported, falling back to only node status updates")
+	}

+	n.controlLoop(ctx)
 	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")
+func (n *Node) controlLoop(ctx context.Context) {
+	pingTimer := time.NewTimer(n.pingInterval)
+	defer pingTimer.Stop()
+
+	statusTimer := time.NewTimer(n.statusInterval)
+	defer statusTimer.Stop()
+	if n.disableLease {
+		// hack to make sure this channel always blocks since we won't be using it
+		if !statusTimer.Stop() {
+			<-statusTimer.C
+		}
+	}
+
+	for {
+		select {
+		case <-ctx.Done():
+			return
+		case updated := <-n.chStatusUpdate:
+			var t *time.Timer
+			if n.disableLease {
+				t = pingTimer
+			} else {
+				t = statusTimer
+			}
+
+			log.G(ctx).Debug("Received node status update")
+			// Performing a status update so stop/reset the status update timer in this
+			// branch otherwise there could be an uneccessary status update.
+			if !t.Stop() {
+				<-t.C
+			}
+
+			n.n.Status = updated.Status
+			if err := n.updateStatus(ctx); err != nil {
+				log.G(ctx).WithError(err).Error("Error handling node status update")
+			}
+			t.Reset(n.statusInterval)
+		case <-statusTimer.C:
+			if err := n.updateStatus(ctx); err != nil {
+				log.G(ctx).WithError(err).Error("Error handling node status update")
+			}
+			statusTimer.Reset(n.statusInterval)
+		case <-pingTimer.C:
+			if err := n.handlePing(ctx); err != nil {
+				log.G(ctx).WithError(err).Error("Error while handling node ping")
+			} else {
+				log.G(ctx).Debug("Successful node ping")
+			}
+			pingTimer.Reset(n.pingInterval)
+		}
+	}
+}
+
+func (n *Node) handlePing(ctx context.Context) (retErr error) {
+	ctx, span := trace.StartSpan(ctx, "node.handlePing")
+	defer span.End()
+	defer func() {
+		span.SetStatus(ocstatus.FromError(retErr))
+	}()
+
+	if err := n.p.Ping(ctx); err != nil {
+		return pkgerrors.Wrap(err, "error whiling pinging node provider")
+	}
+
+	if n.disableLease {
+		return n.updateStatus(ctx)
+	}
+
+	return n.updateLease(ctx)
+}
+
+func (n *Node) updateLease(ctx context.Context) error {
+	l, err := UpdateNodeLease(ctx, n.leases, newLease(n.lease))
+	if err != nil {
+		return err
+	}
+
+	n.lease = l
+	return nil
+}
+
+func (n *Node) updateStatus(ctx context.Context) error {
+	updateNodeStatusHeartbeat(n.n)
+
+	node, err := UpdateNodeStatus(ctx, n.nodes, n.n)
+	if err != nil {
+		return err
+	}
+
+	n.n = node
+	return nil
+}
+
+func ensureLease(ctx context.Context, leases v1beta1.LeaseInterface, lease *coord.Lease) (*coord.Lease, error) {
+	l, err := leases.Create(lease)
+	if err != nil {
+		switch {
+		case errors.IsNotFound(err):
+			log.G(ctx).WithError(err).Info("Node lease not supported")
+			return nil, err
+		case errors.IsAlreadyExists(err):
+			if err := leases.Delete(lease.Name, nil); err != nil && !errors.IsNotFound(err) {
+				log.G(ctx).WithError(err).Error("could not delete old node lease")
+				return nil, pkgerrors.Wrap(err, "old lease exists but could not delete it")
+			}
+			l, err = leases.Create(lease)
+		}
+	}
+
+	return l, err
+}
+
+// UpdateNodeLease updates the node lease.
+//
+// If this function returns an errors.IsNotFound(err) error, this likely means
+// that node leases are not supported, if this is the case, call UpdateNodeStatus
+// instead.
+//
+// If you use this function, it is up to you to syncronize this with other operations.
+func UpdateNodeLease(ctx context.Context, leases v1beta1.LeaseInterface, lease *coord.Lease) (*coord.Lease, error) {
+	ctx, span := trace.StartSpan(ctx, "node.UpdateNodeLease")
 	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 retrive node")
-		span.SetStatus(ocstatus.FromError(err))
-		return
+	ctx = span.WithFields(ctx, log.Fields{
+		"lease.name": lease.Name,
+		"lease.time": lease.Spec.RenewTime,
+	})
+
+	if lease.Spec.LeaseDurationSeconds != nil {
+		ctx = span.WithField(ctx, "lease.expiresSeconds", *lease.Spec.LeaseDurationSeconds)
 	}

-	ctx = addNodeAttributes(ctx, span, n)
-	log.G(ctx).Debug("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(ocstatus.FromError(err))
-		} else {
-			log.G(ctx).Debug("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)
+	l, err := leases.Update(lease)
 	if err != nil {
-		log.G(ctx).WithError(err).Error("Failed to update node")
-		span.SetStatus(ocstatus.FromError(err))
-		return
+		if errors.IsNotFound(err) {
+			log.G(ctx).Debug("lease not found")
+			l, err = ensureLease(ctx, leases, lease)
+		}
+		if err != nil {
+			span.SetStatus(ocstatus.FromError(err))
+			return nil, err
+		}
+		log.G(ctx).Debug("created new lease")
+	} else {
+		log.G(ctx).Debug("updated lease")
 	}
+
+	return l, nil
+}
+
+// just so we don't have to allocate this on every get request
+var emptyGetOptions = metav1.GetOptions{}
+
+// UpdateNodeStatus triggers an update to the node status in Kubernetes.
+// It first fetches the current node details and then sets the status according
+// to the passed in node object.
+//
+// If you use this function, it is up to you to syncronize this with other operations.
+func UpdateNodeStatus(ctx context.Context, nodes v1.NodeInterface, n *corev1.Node) (*corev1.Node, error) {
+	ctx, span := trace.StartSpan(ctx, "UpdateNodeStatus")
+	defer span.End()
+
+	node, err := nodes.Get(n.Name, emptyGetOptions)
+	if err != nil {
+		if !errors.IsNotFound(err) {
+			span.SetStatus(ocstatus.FromError(err))
+			return nil, err
+		}
+
+		log.G(ctx).Debug("node not found")
+		node, err = nodes.Create(n.DeepCopy())
+		if err != nil {
+			return nil, err
+		}
+		log.G(ctx).Debug("created new node")
+		return node, nil
+	}
+
+	log.G(ctx).Debug("got node from api server")
+
+	node.ResourceVersion = ""
+	node.Status = n.Status
+
+	ctx = addNodeAttributes(ctx, span, node)
+
+	updated, err := nodes.UpdateStatus(node)
+	if err != nil {
+		return nil, err
+	}
+
+	log.G(ctx).WithField("resourceVersion", updated.ResourceVersion).Debug("updated node status in api server")
+	return updated, nil
+}
+
+func newLease(base *coord.Lease) *coord.Lease {
+	var lease *coord.Lease
+	if base == nil {
+		lease = &coord.Lease{}
+	} else {
+		lease = base.DeepCopy()
+	}
+
+	lease.Spec.RenewTime = &metav1.MicroTime{Time: time.Now()}
+	return lease
+}
+
+func setLeaseAttrs(l *coord.Lease, n *corev1.Node, dur time.Duration) {
+	if l.Name == "" {
+		l.Name = n.Name
+	}
+	if l.Spec.HolderIdentity == nil {
+		l.Spec.HolderIdentity = &n.Name
+	}
+
+	if l.Spec.LeaseDurationSeconds == nil {
+		d := int32(dur.Seconds()) * 5
+		l.Spec.LeaseDurationSeconds = &d
+	}
+}
+
+func updateNodeStatusHeartbeat(n *corev1.Node) {
+	now := metav1.NewTime(time.Now())
+	for i, _ := range n.Status.Conditions {
+		n.Status.Conditions[i].LastHeartbeatTime = now
+	}
+}
+
+// NaiveNodeProvider is a basic node provider that only uses the passed in context
+// on `Ping` to determine if the node is healthy.
+type NaiveNodeProvider struct{}
+
+// Ping just implements the NodeProvider interface.
+// It returns the error from the passed in context only.
+func (NaiveNodeProvider) Ping(ctx context.Context) error {
+	return ctx.Err()
+}
+
+// NotifyNodeStatus implements the NodeProvider interface.
+//
+// This NaiveNodeProvider does not support updating node status and so this
+// function is a no-op.
+func (NaiveNodeProvider) NotifyNodeStatus(ctx context.Context, f func(*corev1.Node)) {
 }

 type taintsStringer []corev1.Taint
@@ -127,9 +409,9 @@ func (t taintsStringer) String() string {

 func addNodeAttributes(ctx context.Context, span trace.Span, n *corev1.Node) context.Context {
 	return span.WithFields(ctx, log.Fields{
-		"UID":     string(n.UID),
-		"name":    n.Name,
-		"cluster": n.ClusterName,
-		"tains":   taintsStringer(n.Spec.Taints),
+		"node.UID":     string(n.UID),
+		"node.name":    n.Name,
+		"node.cluster": n.ClusterName,
+		"node.taints":  taintsStringer(n.Spec.Taints),
 	})
 }