agent: set a label when after successful os-update

This sets the label
`container-linux-update.v1.coreos.com/reboot-needed: "true"`
on nodes where the OS has been upgraded but not yet rebooted. This is so
daemonsets like tectonic-torcx can run ASAP.

Fixes: #167

Author: Casey Callendrello

doc/labels-and-annotations.md

@@ -30,12 +30,13 @@ A few labels may be set directly by admins to customize behavior. These are call
 | id   | coreos  |  update-agent    | Reflects the ID in `/etc/os-release` |
 | version | 1497.7.0 | update-agent | Reflects the VERSION in `/etc/os-release` |
 | group | stable | update-agent     | Reflects the GROUP in `/usr/share/coreos/update.conf` or `/etc/coreos/update.conf` |
+| reboot-needed | true | update-agent | Reflects the reboot-needed annotation |
 
 **Annotations**
 
 | name | example | setter           | description |
 |------|---------|------------------|-------------|
-| reboot-needed  | true/false | update-agent | Set to true to request a coordinated reboot |
+| reboot-needed  | true/false | update-agent | Updates to true to request a coordinated reboot from the operator |
 | reboot-in-progress | true/false | update-agent | Set to true to indicate a reboot is in progress |
 | status | UPDATE_STATUS_IDLE | update-agent | Reflects the `update_engine` CurrentOperation status value |
 | new-version       | 0.0.0      | update-agent | Reflects the `update_engine` NewVersion status value |

pkg/agent/agent.go

@@ -92,10 +92,14 @@ func (k *Klocksmith) process(stop <-chan struct{}) error {
 		constants.AnnotationRebootInProgress: constants.False,
 		constants.AnnotationRebootNeeded:     constants.False,
 	}
+	labels := map[string]string{
+		constants.LabelRebootNeeded: constants.False,
+	}
 	glog.Infof("Setting annotations %#v", anno)
-	if err := k8sutil.SetNodeAnnotations(k.nc, k.node, anno); err != nil {
+	if err := k8sutil.SetNodeAnnotationsLabels(k.nc, k.node, anno, labels); err != nil {
 		return err
 	}
+
 	// Since we set 'reboot-needed=false', 'ok-to-reboot' should clear.
 	// Wait for it to do so, else we might start reboot-looping
 	if err := k.waitForNotOkToReboot(); err != nil {
@@ -199,14 +203,17 @@ func (k *Klocksmith) updateStatusCallback(s updateengine.Status) {
 		constants.AnnotationNewVersion:      s.NewVersion,
 	}
 
+	labels := map[string]string{}
+
 	// indicate we need a reboot
 	if s.CurrentOperation == updateengine.UpdateStatusUpdatedNeedReboot {
 		glog.Info("Indicating a reboot is needed")
 		anno[constants.AnnotationRebootNeeded] = constants.True
+		labels[constants.LabelRebootNeeded] = constants.True
 	}
 
 	wait.PollUntil(defaultPollInterval, func() (bool, error) {
-		if err := k8sutil.SetNodeAnnotations(k.nc, k.node, anno); err != nil {
+		if err := k8sutil.SetNodeAnnotationsLabels(k.nc, k.node, anno, labels); err != nil {
 			glog.Errorf("Failed to set annotation %q: %v", constants.AnnotationStatus, err)
 			return false, nil
 		}

pkg/constants/constants.go

@@ -12,6 +12,7 @@ const (
 
 	// Key set to "true" by the update-agent when a reboot is requested.
 	AnnotationRebootNeeded = Prefix + "reboot-needed"
+	LabelRebootNeeded      = Prefix + "reboot-needed"
 
 	// Key set to "true" by the update-agent when node-drain and reboot is
 	// initiated.

pkg/k8sutil/metadata.go

@@ -80,8 +80,8 @@ func SetNodeAnnotations(nc v1core.NodeInterface, node string, m map[string]strin
 	})
 }
 
-// SetNodeAnnotationsLabels sets all keys in a and l to their respective values in
-// node's annotations and labels, likewise
+// SetNodeAnnotationsLabels sets all keys in a and l to their values in
+// node's annotations and labels, respectively
 func SetNodeAnnotationsLabels(nc v1core.NodeInterface, node string, a, l map[string]string) error {
 	return UpdateNodeRetry(nc, node, func(n *v1api.Node) {
 		for k, v := range a {