Use InPlacePodVerticalScaling feature gate instead of tweaking cgroups

README.md

@@ -23,12 +23,10 @@ The controller messes with cgroups file `cpu.max` to give that boost (or reset t
 
 ## Install
 
-Use `ko`. Example on a `kind` cluster with cgroups v2 (default on latest operating systems):
+Use `ko`. Example on a `kind` cluster:
 
 ```sh
-KO_DOCKER_REPO=kind.local ko resolve -f config/ | \
-    CGROUP_VERSION=v2 K8S_DISTRIBUTION=kind envsubst | \
-    kubectl apply -f -
+KO_DOCKER_REPO=kind.local ko apply -f config/
 ```
 
 ## Test/Demo
@@ -46,12 +44,10 @@ docker pull python:3.11-alpine
 kind load docker-image python:3.11-alpine
 ```
 
-Install `k8s-pod-cpu-booster` (change `CGROUP_VERSION` to `v1` if you're using cgroups v1):
+Install `k8s-pod-cpu-booster`:
 
 ```sh
-KO_DOCKER_REPO=kind.local ko resolve -f config/ | \
-    CGROUP_VERSION=v2 K8S_DISTRIBUTION=kind envsubst | \
-    kubectl apply -f -
+KO_DOCKER_REPO=kind.local ko apply -f config/
 ```
 
 Start two similar pods with low CPU limits and running `python -m http.server`, with a readiness probe configured to check when the http server is started. The only differences are the name (obviously), and the annotation `norbjd.github.io/k8s-pod-cpu-booster-enabled`:
@@ -90,11 +86,11 @@ done
 Example result:
 
 ```
-python-with-default-boost started at: 2023-09-03T15:55:45Z / ready at: 2023-09-03T15:55:46Z
-python-no-boost started at: 2023-09-03T15:55:44Z / ready at: 2023-09-03T15:55:58Z
+python-with-default-boost started at: 2023-10-28T14:00:46Z / ready at: 2023-10-28T14:00:49Z
+python-no-boost started at: 2023-10-28T14:00:46Z / ready at: 2023-10-28T14:01:04Z
 ```
 
-Here, the pod with the CPU boost (`python-with-default-boost`) took around 1 second to start, while the pod without CPU boost (`python-no-boost`) took around 14 seconds.
+Here, the pod with the CPU boost (`python-with-default-boost`) took around 3 seconds to start, while the pod without CPU boost (`python-no-boost`) took around 18 seconds.
 
 Cleanup:
 

cmd/main.go

@@ -2,9 +2,7 @@ package main
 
 import (
 	"flag"
-	"os"
 
-	"github.com/norbjd/k8s-pod-cpu-booster/pkg/cgroup"
 	"github.com/norbjd/k8s-pod-cpu-booster/pkg/informer"
 
 	"k8s.io/client-go/kubernetes"
@@ -26,29 +24,5 @@ func main() {
 		panic(err)
 	}
 
-	var cgroupHandler cgroup.Handler
-
-	// TODO: instead of using an env var, detect automatically the right cgroup handler to use
-	switch os.Getenv("CGROUP_VERSION") {
-	case "v1":
-		switch os.Getenv("K8S_DISTRIBUTION") {
-		case "kapsule":
-			klog.Info("Using V1KapsuleHandler")
-			cgroupHandler = cgroup.V1KapsuleHandler{}
-		default:
-			klog.Info("Using V1KindHandler")
-			cgroupHandler = cgroup.V1KindHandler{}
-		}
-	default:
-		switch os.Getenv("K8S_DISTRIBUTION") {
-		case "kapsule":
-			klog.Info("Using V2KapsuleHandler")
-			cgroupHandler = cgroup.V2KapsuleHandler{}
-		default:
-			klog.Info("Using V2KindHandler")
-			cgroupHandler = cgroup.V2KindHandler{}
-		}
-	}
-
-	informer.Run(clientset, cgroupHandler)
+	informer.Run(clientset)
 }

config/200-rbac.yaml

@@ -17,6 +17,7 @@ rules:
   - list
   - watch
   - get
+  - update
 ---
 apiVersion: rbac.authorization.k8s.io/v1
 kind: ClusterRoleBinding

config/300-pod-cpu-booster.yaml

@@ -20,25 +20,12 @@ spec:
           valueFrom:
             fieldRef:
               fieldPath: spec.nodeName
-        - name: CGROUP_VERSION
-          value: "$CGROUP_VERSION"
-        - name: K8S_DISTRIBUTION
-          value: "$K8S_DISTRIBUTION"
         resources:
           limits:
             cpu: 100m
             memory: 100Mi
           requests:
             cpu: 100m
             memory: 100Mi
-        securityContext:
-          runAsUser: 0 # required otherwise we won't be able to edit files under /sys/fs/cgroup
-        volumeMounts:
-        - name: sysfscgroup
-          mountPath: /sys/fs/cgroup
       serviceAccountName: pod-cpu-booster
       terminationGracePeriodSeconds: 0 # TODO: change for production environments
-      volumes:
-      - name: sysfscgroup
-        hostPath:
-          path: /sys/fs/cgroup

examples/kind-config.yaml

@@ -1,5 +1,7 @@
 kind: Cluster
 apiVersion: kind.x-k8s.io/v1alpha4
+featureGates:
+  InPlacePodVerticalScaling: true
 nodes:
 - role: control-plane
   image: kindest/node:v1.28.0@sha256:b7a4cad12c197af3ba43202d3efe03246b3f0793f162afb40a33c923952d5b31

examples/python-with-default-boost.yaml

@@ -19,6 +19,9 @@ spec:
       periodSeconds: 1
       successThreshold: 1
       timeoutSeconds: 1
+    resizePolicy:
+    - resourceName: cpu
+      restartPolicy: NotRequired # this is very important to be able to update the CPU resources in place (no need to restart the pod)
     resources:
       requests:
         cpu: 50m