sequence.wsd

@startuml "pmem-csi-persistent-sequence-diagram"

title \nDynamic provisioning of a pmem-csi persistent volume\n

skinparam BoxPadding 40

actor Admin as admin #red
actor User as user
entity Kubernetes as k8s
box "Master node"
entity kubelet as masterkubelet
participant "external-provisioner" as provisioner
participant "external-attacher" as attacher
participant "pmem-csi-driver" as masterdriver
endbox

box "Computee node XYZ"
entity kubelet as nodekubelet
participant "pmem-csi-driver" as nodedriver
endbox

== Driver setup ==
admin->k8s:Label nvdimm nodes: <b>storage=nvdimm</b>
k8s->admin

admin->k8s:deploy driver\nkubectl create -f pmem-csi.yaml
k8s->admin
k8s->masterkubelet:start driver pod
masterkubelet-->provisioner:start container
masterkubelet-->attacher:start container
masterkubelet-->masterdriver:start container
note right of masterdriver
    listen on tcp port 10000
end note
k8s-->nodekubelet:start driver pod
nodekubelet-->nodedriver:start container
note left of nodedriver
    * prepare logical volume groups
    * listen on port 10001
    * listen on unix socket:
      /var/lib/kubelet/plugins/pmem-csi/csi.sock
end note
nodedriver->masterdriver:RegistryServer.RegisterNodeController(\n{nodeId:"node-xyz", endpoint:"http://ip:10001"})

' install a storage class
admin->k8s:create StorageClass\nkubectl create -f pmem-storageclass.yaml
note left of k8s
  metadata:
    name: pmem-csi-sc
  volumeBindingMode: <b>Immediate
end note
k8s->admin

== Volume provisioning ==
admin->k8s:create PVC object\nkubectl create -f pmem-pvc.yaml
k8s->admin
k8s-->provisioner:<<Event>>\nPersistentVolumeClaim created
activate provisioner
provisioner->masterdriver:CSI.Controller.CreateVolume()
masterdriver->nodedriver:csi.Controller.CreateVolume()
nodedriver->nodedriver:create pmem volume
nodedriver->masterdriver:success
masterdriver->provisioner:success
note left of masterdriver
  prepare Topology information:
  Volume{
    accessible_topology: [ segments:{ "pmem-csi.intel.com/node":"node-xyz"} ]
  }
end note
provisioner->k8s:Create PV object
deactivate provisioner

== Volume usage ==
user->k8s:Create application pod
note left of k8s
  volumes:
  - name: my-csi-volume
    persistentVolumeClaim:
      claimName: pmem-csi-pvc
end note
k8s->user:success

k8s->nodekubelet:schedules pod on node-xyz

k8s-->nodekubelet:make available volume to pod
nodekubelet->nodedriver:csi.Node.StageVolume()
activate nodedriver
nodedriver->nodedriver:mount pmem device
nodedriver->nodekubelet:success
deactivate nodedriver

nodekubelet->nodedriver:csi.Node.PublishVolume()
activate nodedriver
nodedriver->nodedriver:bind mount pmem device
nodedriver->nodekubelet:success
deactivate nodedriver

' deprovision a cache volume
== Volume Deletion ==
' stop pod
user->k8s:stop applicaiton pod
k8s->user:success
k8s->nodekubelet:stop pod containers

nodekubelet->nodedriver:csi.Node.UnPublishVolume()
activate nodedriver
nodedriver->nodedriver:unmout pod's bind mount
nodedriver->nodekubelet:success
deactivate nodedriver

nodekubelet->nodedriver:csi.Node.UnstageVolume()
activate nodedriver
nodedriver->nodedriver:unmount pmem device
nodedriver->nodekubelet:success
deactivate nodedriver

'''''''''''''''''''''''''''
admin->k8s:Delete PVC object\nkubectl delete pvc pmem-pvc-cache
k8s->admin
k8s-->provisioner:<<Event>>\nPersistentVolumeClaim deleted
activate provisioner
provisioner->masterdriver:CSI.Controller.DeleteVolume()
masterdriver->nodedriver:csi.Controller.DeleteVolume()
nodedriver->nodedriver:delete pmem volume
nodedriver->masterdriver:success
masterdriver->nodedriver:csi.Controller.DeleteVolume()
nodedriver->nodedriver:delete pmem volume
nodedriver->masterdriver:success
masterdriver->provisioner:success
provisioner->k8s:Delete PV object
deactivate provisioner

@enduml