Move some boiler plate startup logic to nodeutil

This makes a controller that handles the startup for the node and pod
controller.
Later if we add an "api controller" it can also be added here.

This is just part of reducing some of the boiler plate code so it is
easier to get off of node-cli.

node/nodeutil/controller.go

@@ -0,0 +1,136 @@
+package nodeutil
+
+import (
+	"context"
+	"fmt"
+	"time"
+
+	"github.com/virtual-kubelet/virtual-kubelet/node"
+)
+
+// ControllerManager helps manage the startup/shutdown procedure for other controllers.
+// It is intended as a convenience to reduce boiler plate code for starting up controllers.
+//
+// Must be created with constructor `NewControllerManager`.
+type ControllerManager struct {
+	nc *node.NodeController
+	pc *node.PodController
+
+	ready chan struct{}
+	done  chan struct{}
+	err   error
+}
+
+// NewControllerManager creates a new ControllerManager.
+func NewControllerManager(nc *node.NodeController, pc *node.PodController) *ControllerManager {
+	return &ControllerManager{
+		nc:    nc,
+		pc:    pc,
+		ready: make(chan struct{}),
+		done:  make(chan struct{}),
+	}
+}
+
+// NodeController returns the configured node controller.
+func (c *ControllerManager) NodeController() *node.NodeController {
+	return c.nc
+}
+
+// PodController returns the configured pod controller.
+func (c *ControllerManager) PodController() *node.PodController {
+	return c.pc
+}
+
+// Run starts all the underlying controllers
+func (c *ControllerManager) Run(ctx context.Context, workers int) (retErr error) {
+	ctx, cancel := context.WithCancel(ctx)
+	defer cancel()
+
+	go c.pc.Run(ctx, workers) // nolint:errcheck
+
+	defer func() {
+		cancel()
+
+		<-c.pc.Done()
+
+		c.err = retErr
+		close(c.done)
+	}()
+
+	select {
+	case <-ctx.Done():
+		return c.err
+	case <-c.pc.Ready():
+	case <-c.pc.Done():
+		return c.pc.Err()
+	}
+
+	go c.nc.Run(ctx) // nolint:errcheck
+
+	defer func() {
+		cancel()
+		<-c.nc.Done()
+	}()
+
+	select {
+	case <-ctx.Done():
+		c.err = ctx.Err()
+		return c.err
+	case <-c.nc.Ready():
+	case <-c.nc.Done():
+		return c.nc.Err()
+	}
+
+	close(c.ready)
+
+	select {
+	case <-c.nc.Done():
+		cancel()
+		return c.nc.Err()
+	case <-c.pc.Done():
+		cancel()
+		return c.pc.Err()
+	}
+}
+
+// WaitReady waits for the specified timeout for the controller to be ready.
+//
+// The timeout is for convenience so the caller doesn't have to juggle an extra context.
+func (c *ControllerManager) WaitReady(ctx context.Context, timeout time.Duration) error {
+	if timeout > 0 {
+		var cancel func()
+		ctx, cancel = context.WithTimeout(ctx, timeout)
+		defer cancel()
+	}
+
+	select {
+	case <-c.ready:
+		return nil
+	case <-c.done:
+		return fmt.Errorf("controller exited before ready: %w", c.err)
+	case <-ctx.Done():
+		return ctx.Err()
+	}
+}
+
+// Ready returns a channel that will be closed after the controller is ready.
+func (c *ControllerManager) Ready() <-chan struct{} {
+	return c.ready
+}
+
+// Done returns a channel that will be closed when the controller has exited.
+func (c *ControllerManager) Done() <-chan struct{} {
+	return c.done
+}
+
+// Err returns any error that occurred with the controller.
+//
+// This always return nil before `<-Done()`.
+func (c *ControllerManager) Err() error {
+	select {
+	case <-c.Done():
+		return c.err
+	default:
+		return nil
+	}
+}