DRA: "Structured Parameters" as base, "classic" DRA as extension

We decided to focus on structured parameters as the part of DRA which will get
moved to beta first. "Classic" DRA (PodSchedulingContext, support for control
plane controllers) will remain in alpha. It needs a separate feature gate.

Therefore the description of DRA in the two KEPs gets shifted around such that
the "structured parameters" KEP is a stand-alone, complete description of
everything needed for using DRA like that.

The original KEP is now an extension of that and describes PodSchedulingContext
and the interaction with a DRA driver control plane controller. Immediate
allocation is defined there because it does not make much sense for structured
parameters.

Mostly this was just a matter of copying text around and updating the wording.
Changes that go beyond those editorial changes are:

- title changes

- new diagram for "structured parameters"

- ResourceClass.StructuredParameters in 4381 became
  ResourceClass.ControlPlaneController in 3063 (different default,
  breaking change!)

- new DRAControlPlaneController feature gate for everything in 3063

- removal of the kubelet v1alpha2 gRPC
  interface (kubernetes/kubernetes#124316).

- updated description of ephemeral ResourceClaim namimg (did not match
  the current implementation with generated names)

- added NodeListAndWatchResources kubelet gRPC call

Author: pohly

keps/sig-node/3063-dynamic-resource-allocation/README.md

@@ -11,7 +11,7 @@ component Kubernetes {
   component apiserver {
       file Pod
       file ResourceClaim
-      file PodScheduling
+      file PodSchedulingContext
   }
   component scheduler {
     component "resource plugin" as k8sresourceplugin
@@ -29,19 +29,19 @@ controllermanager -[hidden]> kubelet
 drivercontroller -[hidden]> driverplugin
 
 Pod <. ResourceClaim: owned by\n(if created from template)
-Pod <. PodScheduling: owned by
+Pod <. PodSchedulingContext: owned by
 
 
 Pod -u-> k8sresourceclaimcontroller: read claim template\nfrom Pod spec
-ResourceClaim <-u- k8sresourceclaimcontroller: create claim,\nclean up users
+ResourceClaim <-u- k8sresourceclaimcontroller: create claim,\nclean up users,\ntrigger deallocation\n
 ResourceClaim <-u-> kubelet
-k8sresourceplugin <-u-> PodScheduling
+k8sresourceplugin <-u-> PodSchedulingContext
 
 Pod <--> scheduler
 ResourceClaim <--> k8sresourceplugin
 
 ResourceClaim <-> drivercontroller
 pluginmanager <-> driverplugin
 resourcemanager <-> driverplugin
-PodScheduling <-> drivercontroller
+PodSchedulingContext <-> drivercontroller
 @enduml

keps/sig-node/3063-dynamic-resource-allocation/components.png

@@ -24,7 +24,7 @@ stage: alpha
 # The most recent milestone for which work toward delivery of this KEP has been
 # done. This can be the current (upcoming) milestone, if it is being actively
 # worked on.
-latest-milestone: "v1.30"
+latest-milestone: "v1.31"
 
 # The milestone at which this feature was, or is targeted to be, at each stage.
 milestone:
@@ -37,6 +37,11 @@ feature-gates:
       - kube-controller-manager
       - kube-scheduler
       - kubelet
+  - name: DRAControlPlaneController
+    components:
+      - kube-apiserver
+      - kube-controller-manager
+      - kube-scheduler
 disable-supported: true
 
 metrics:

keps/sig-node/3063-dynamic-resource-allocation/components.puml

@@ -0,0 +1,35 @@
+# Copyright 2022 The Kubernetes Authors.
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+
+IMAGES += components.png kubelet.png
+
+all: $(IMAGES)
+clean:
+	rm -f $(IMAGES)
+
+# We use the http://plantuml.com/plantuml server to generate
+# images. That way nothing needs to be installed besides Go.
+DOC_PLANTUML_GO = $(shell go env GOPATH)/bin/plantuml-go
+
+%.png: %.puml $(DOC_PLANTUML_GO)
+	$(DOC_PLANTUML_GO) -format png $<
+
+%.svg: %.puml $(DOC_PLANTUML_GO)
+	$(DOC_PLANTUML_GO) -format svg $<
+
+# Builds the binary in GOPATH/bin. Changing into / first avoids
+# modifying the project's go.mod file.
+$(DOC_PLANTUML_GO):
+	cd / && go get github.com/acarlson99/plantuml-go

keps/sig-node/3063-dynamic-resource-allocation/kep.yaml

@@ -0,0 +1,60 @@
+@startuml
+!theme reddress-lightblue
+skinparam componentStyle rectangle
+left to right direction
+
+cloud "resource driver" as resourcedriver {
+  component "CRD controller" as drivercrdcontroller
+  component "kubelet plugin" as driverplugin
+}
+
+component Kubernetes {
+  component apiserver {
+    component namespaced {
+      file ResourceClaimTemplate
+      file Pod
+      file ResourceClaim
+      file DriverCRDParameters
+      file ResourceClaimParameters
+     }
+     component "cluster-scoped" as clusterscoped {
+      file ResourceClass
+      file ResourceSlice
+     }
+  }
+  component scheduler {
+    component "resource plugin" as k8sresourceplugin
+  }
+  component "controller-manager" as controllermanager {
+    component "resource claim controller" as k8sresourceclaimcontroller
+  }
+  component kubelet {
+    component "plugin manager" as pluginmanager
+    component "resource manager" as resourcemanager
+  }
+}
+
+' Kubernetes ---> resourcedriver
+
+ResourceClaimTemplate <. Pod
+Pod <. ResourceClaim: owned by\n(if created from template)
+ResourceClaim .> ResourceClass
+ResourceClaim .> DriverCRDParameters
+ResourceClaimParameters .> DriverCRDParameters: generated from,\nowned by
+
+Pod -u-> k8sresourceclaimcontroller
+ResourceClaimTemplate -u-> k8sresourceclaimcontroller
+ResourceClaim <-u- k8sresourceclaimcontroller: create claim,\nclean up consumers,\ntrigger deallocation
+k8sresourceplugin <- ResourceClaimParameters
+
+Pod <--> kubelet
+Pod <--> scheduler
+ResourceClaim <--> k8sresourceplugin
+
+ResourceClaimParameters <- drivercrdcontroller: create, update
+DriverCRDParameters ---> drivercrdcontroller: read
+resourcemanager <-> driverplugin: calls gRPC methods,\nreceives stream of\nresource information
+ResourceSlice-> k8sresourceplugin: consumes
+resourcemanager --> ResourceSlice: publishes
+pluginmanager <-> driverplugin: registers
+@enduml

keps/sig-node/3063-dynamic-resource-allocation/kubelet.png

@@ -25,7 +25,7 @@ stage: alpha
 # The most recent milestone for which work toward delivery of this KEP has been
 # done. This can be the current (upcoming) milestone, if it is being actively
 # worked on.
-latest-milestone: "v1.30"
+latest-milestone: "v1.31"
 
 # The milestone at which this feature was, or is targeted to be, at each stage.
 milestone:
@@ -34,7 +34,12 @@ milestone:
 # The following PRR answers are required at alpha release
 # List the feature gate name and the components for which it must be enabled
 feature-gates:
-  # DynamicResourceAllocation, same as for DRA without this KEP
+  - name: DynamicResourceAllocation
+    components:
+      - kube-apiserver
+      - kube-controller-manager
+      - kube-scheduler
+      - kubelet
 disable-supported: true
 
 # The following PRR answers are required at beta release