[kubeletstats] Cleanup deprecated *.cpu.utilization metrics and respective feature gate (#42727)

<!--Ex. Fixing a bug - Describe the bug and how this fixes the issue.
Ex. Adding a feature - Explain what this achieves.-->
#### Description
After the merge of
#41042
we need to completely remove the
`receiver.kubeletstats.enableCPUUsageMetrics` feature gate and cleanup
the component accordingly.

The feature gate has been [in place until
v0.131.0](https://github.com/open-telemetry/opentelemetry-collector-contrib/pull/41042/files#diff-3d568b694da81fd8cca718ee598c1fa14d20176a73af0f8d009388f5a6c2e11dR33)
hence now it can be removed entirely.

<!-- Issue number (e.g. #1234) or full URL to issue, if applicable. -->
#### Link to tracking issue
Fixes
#41178

Supersedes
#41880.

<!--Describe what testing was performed and which tests were added.-->
#### Testing
Updated

<!--Describe the documentation added.-->
#### Documentation
Updated

<!--Please delete paragraphs that you did not use before submitting.-->

Co-authored-by: mugund10 <[email protected]>

Signed-off-by: ChrsMark <[email protected]>
Co-authored-by: mugund10 <[email protected]>

Author: ChrsMark

receiver/kubeletstatsreceiver/README.md

@@ -17,11 +17,6 @@
 The Kubelet Stats Receiver pulls node, pod, container, and volume metrics from the API server on a kubelet
 and sends it down the metric pipeline for further processing.
 
-> [!WARNING]
-> The `receiver.kubeletstats.enableCPUUsageMetrics` feature gate was moved to stage `Stable`.
-> Deprecated metrics cannot be used anymore.
-> For more information which metrics are affected see [here](#metrics-deprecation).
-
 ## Metrics
 
 Details about the metrics produced by this receiver can be found in [metadata.yaml](./metadata.yaml) with further documentation in [documentation.md](./documentation.md)
@@ -332,24 +327,3 @@ rules:
     resources: ["nodes/proxy"]
     verbs: ["get"]
 ```
-
-### Metrics deprecation
-
-The following metrics were deprecated and renamed from version `v0.125.0`:
-
-- `k8s.node.cpu.utilization` (renamed to `k8s.node.cpu.usage`)
-- `k8s.pod.cpu.utilization` (renamed to `k8s.pod.cpu.usage`)
-- `container.cpu.utilization` (renamed to `container.cpu.usage`)
-
-The above metrics show usage counted in CPUs and it's not a percentage of used resources.
-These metrics were previously incorrectly named using the utilization term.
-
-#### `receiver.kubeletstats.enableCPUUsageMetrics` feature gate
-
-- alpha: when enabled it makes the `.cpu.usage` metrics enabled by default, disabling the `.cpu.utilization` metrics
-- beta: `.cpu.usage` metrics are enabled by default and any configuration enabling the deprecated `.cpu.utilization` metrics will be failing. Explicitly disabling the feature gate provides the old (deprecated) behavior.
-- stable: `.cpu.usage` metrics are enabled by default and the deprecated metrics are completely removed.
-- removed three releases after stable.
-
-More information about the deprecation plan and
-the background reasoning can be found at <https://github.com/open-telemetry/opentelemetry-collector-contrib/issues/27885>.

receiver/kubeletstatsreceiver/documentation.md

@@ -386,14 +386,6 @@ metrics:
     enabled: true
 ```
 
-### container.cpu.utilization
-
-Container CPU utilization
-
-| Unit | Metric Type | Value Type |
-| ---- | ----------- | ---------- |
-| 1 | Gauge | Double |
-
 ### container.uptime
 
 The time since the container started
@@ -450,14 +442,6 @@ Container memory utilization as a ratio of the container's requests
 | ---- | ----------- | ---------- |
 | 1 | Gauge | Double |
 
-### k8s.node.cpu.utilization
-
-Node CPU utilization
-
-| Unit | Metric Type | Value Type |
-| ---- | ----------- | ---------- |
-| 1 | Gauge | Double |
-
 ### k8s.node.uptime
 
 The time since the node started
@@ -474,14 +458,6 @@ Pod cpu utilization as a ratio of the node's capacity
 | ---- | ----------- | ---------- |
 | 1 | Gauge | Double |
 
-### k8s.pod.cpu.utilization
-
-Pod CPU utilization
-
-| Unit | Metric Type | Value Type |
-| ---- | ----------- | ---------- |
-| 1 | Gauge | Double |
-
 ### k8s.pod.cpu_limit_utilization
 
 Pod cpu utilization as a ratio of the pod's total container limits. If any container is missing a limit the metric is not emitted.

receiver/kubeletstatsreceiver/factory.go

@@ -9,7 +9,6 @@ import (
 
 	"go.opentelemetry.io/collector/component"
 	"go.opentelemetry.io/collector/consumer"
-	"go.opentelemetry.io/collector/featuregate"
 	"go.opentelemetry.io/collector/receiver"
 	"go.opentelemetry.io/collector/scraper/scraperhelper"
 	"go.uber.org/zap"
@@ -21,17 +20,7 @@ import (
 )
 
 const (
-	metricGroupsConfig               = "metric_groups"
-	enableCPUUsageMetricsFeatureFlag = "receiver.kubeletstats.enableCPUUsageMetrics"
-)
-
-var EnableCPUUsageMetrics = featuregate.GlobalRegistry().MustRegister(
-	enableCPUUsageMetricsFeatureFlag,
-	featuregate.StageStable,
-	featuregate.WithRegisterDescription("When enabled the container.cpu.utilization, k8s.pod.cpu.utilization and k8s.node.cpu.utilization metrics will be replaced by the container.cpu.usage, k8s.pod.cpu.usage and k8s.node.cpu.usage"),
-	featuregate.WithRegisterFromVersion("v0.110.0"),
-	featuregate.WithRegisterToVersion("v0.131.0"),
-	featuregate.WithRegisterReferenceURL("https://github.com/open-telemetry/opentelemetry-collector-contrib/issues/27885"),
+	metricGroupsConfig = "metric_groups"
 )
 
 var defaultMetricGroups = []kubelet.MetricGroup{

receiver/kubeletstatsreceiver/go.mod

@@ -20,7 +20,6 @@ require (
 	go.opentelemetry.io/collector/confmap/xconfmap v0.135.1-0.20250911155607-37a3ace6274c
 	go.opentelemetry.io/collector/consumer v1.41.1-0.20250911155607-37a3ace6274c
 	go.opentelemetry.io/collector/consumer/consumertest v0.135.1-0.20250911155607-37a3ace6274c
-	go.opentelemetry.io/collector/featuregate v1.41.1-0.20250911155607-37a3ace6274c
 	go.opentelemetry.io/collector/filter v0.135.1-0.20250911155607-37a3ace6274c
 	go.opentelemetry.io/collector/pdata v1.41.1-0.20250911155607-37a3ace6274c
 	go.opentelemetry.io/collector/pipeline v1.41.1-0.20250911155607-37a3ace6274c
@@ -110,6 +109,7 @@ require (
 	go.opentelemetry.io/collector/consumer/xconsumer v0.135.1-0.20250911155607-37a3ace6274c // indirect
 	go.opentelemetry.io/collector/extension/extensionauth v1.41.1-0.20250911155607-37a3ace6274c // indirect
 	go.opentelemetry.io/collector/extension/extensionmiddleware v0.135.1-0.20250911155607-37a3ace6274c // indirect
+	go.opentelemetry.io/collector/featuregate v1.41.1-0.20250911155607-37a3ace6274c // indirect
 	go.opentelemetry.io/collector/internal/sharedcomponent v0.135.1-0.20250911155607-37a3ace6274c // indirect
 	go.opentelemetry.io/collector/internal/telemetry v0.135.1-0.20250911155607-37a3ace6274c // indirect
 	go.opentelemetry.io/collector/pdata/pprofile v0.135.1-0.20250911155607-37a3ace6274c // indirect

receiver/kubeletstatsreceiver/internal/kubelet/cpu.go

@@ -37,8 +37,6 @@ func addCPUUtilizationMetrics(
 	r resources,
 	nodeCPULimit float64,
 ) {
-	cpuMetrics.Utilization(mb, currentTime, usageCores)
-
 	if nodeCPULimit > 0 {
 		cpuMetrics.NodeUtilization(mb, currentTime, usageCores/nodeCPULimit)
 	}