configurable pv recyclers

pkg/volume/plugins.go

@@ -169,8 +169,22 @@ func (spec *Spec) Name() string {
 // The binary should still use strong typing for this value when binding CLI values before they are passed as strings
 // in OtherAttributes.
 type VolumeConfig struct {
-	// thockin: do we want to wait on this until we have an actual use case?  I can change the comments above to
-	// reflect our intention for one-off config.
+	// RecyclerPodTemplate is pod template that understands how to scrub clean a persistent volume after its release.
+	// The template is used by plugins which override specific properties of the pod in accordance with that plugin.
+	// See NewPersistentVolumeRecyclerPodTemplate for the properties that are expected to be overridden.
+	RecyclerPodTemplate *api.Pod
+
+	// RecyclerMinimumTimeout is the minimum amount of time in seconds for the recycler pod's ActiveDeadlineSeconds attribute.
+	// Added to the minimum timeout is the increment per Gi of capacity.
+	RecyclerMinimumTimeout int
+
+	// RecyclerTimeoutIncrement is the number of seconds added to the recycler pod's ActiveDeadlineSeconds for each
+	// Gi of capacity in the persistent volume.
+	// Example: 5Gi volume x 30s increment = 150s + 30s minimum = 180s ActiveDeadlineSeconds for recycler pod
+	RecyclerTimeoutIncrement int
+
+	// OtherAttributes stores config as strings.  These strings are opaque to the system and only understood by the binary
+	// hosting the plugin and the plugin itself.
 	OtherAttributes map[string]string
 }
 
@@ -301,3 +315,49 @@ func (pm *VolumePluginMgr) FindRecyclablePluginBySpec(spec *Spec) (RecyclableVol
 	}
 	return nil, fmt.Errorf("no recyclable volume plugin matched")
 }
+
+// NewPersistentVolumeRecyclerPodTemplate creates a template for a recycler pod.  By default, a recycler pod simply runs
+// "rm -rf" on a volume and tests for emptiness.  Most attributes of the template will be correct for most
+// plugin implementations.  The following attributes can be overridden per plugin via configuration:
+//
+// 1.  pod.Spec.Volumes[0].VolumeSource must be overridden.  Recycler implementations without a valid VolumeSource will fail.
+// 2.  pod.GenerateName helps distinguish recycler pods by name.  Recommended. Default is "pv-recycler-".
+// 3.  pod.Spec.ActiveDeadlineSeconds gives the recycler pod a maximum timeout before failing.  Recommended.  Default is 60 seconds.
+//
+// See HostPath and NFS for working recycler examples
+func NewPersistentVolumeRecyclerPodTemplate() *api.Pod {
+	timeout := int64(60)
+	pod := &api.Pod{
+		ObjectMeta: api.ObjectMeta{
+			GenerateName: "pv-recycler-",
+			Namespace:    api.NamespaceDefault,
+		},
+		Spec: api.PodSpec{
+			ActiveDeadlineSeconds: &timeout,
+			RestartPolicy:         api.RestartPolicyNever,
+			Volumes: []api.Volume{
+				{
+					Name: "vol",
+					// IMPORTANT!  All plugins using this template MUST override pod.Spec.Volumes[0].VolumeSource
+					// Recycler implementations without a valid VolumeSource will fail.
+					VolumeSource: api.VolumeSource{},
+				},
+			},
+			Containers: []api.Container{
+				{
+					Name:    "pv-recycler",
+					Image:   "gcr.io/google_containers/busybox",
+					Command: []string{"/bin/sh"},
+					Args:    []string{"-c", "test -e /scrub && echo $(date) > /scrub/trash.txt && rm -rf /scrub/* /scrub/.* && test -z \"$(ls -A /scrub)\" || exit 1"},
+					VolumeMounts: []api.VolumeMount{
+						{
+							Name:      "vol",
+							MountPath: "/scrub",
+						},
+					},
+				},
+			},
+		},
+	}
+	return pod
+}