Document PodAndContainerStatsFromCRI feature

Signed-off-by: Peter Hunt <[email protected]>

Author: haircommander

content/en/docs/reference/command-line-tools-reference/feature-gates.md

@@ -362,6 +362,7 @@ different Kubernetes components.
 | `PersistentLocalVolumes` | `false` | Alpha | 1.7 | 1.9 |
 | `PersistentLocalVolumes` | `true` | Beta | 1.10 | 1.13 |
 | `PersistentLocalVolumes` | `true` | GA | 1.14 | - |
+| `PodAndContainerStatsFromCRI` | `false` | Alpha | 1.23 | |
 | `PodDisruptionBudget` | `false` | Alpha | 1.3 | 1.4 |
 | `PodDisruptionBudget` | `true` | Beta | 1.5 | 1.20 |
 | `PodDisruptionBudget` | `true` | GA | 1.21 | - |
@@ -862,6 +863,8 @@ Each feature gate is designed for enabling/disabling a specific feature:
    feature which allows users to influence ReplicaSet downscaling order.
 - `PersistentLocalVolumes`: Enable the usage of `local` volume type in Pods.
   Pod affinity has to be specified if requesting a `local` volume.
+- `PodAndContainerStatsFromCRI`: Configure the kubelet to gather container and pod stats from the CRI container runtime
+   rather than gathering them from cAdvisor.
 - `PodDisruptionBudget`: Enable the [PodDisruptionBudget](/docs/tasks/run-application/configure-pdb/) feature.
 - `PodAffinityNamespaceSelector`: Enable the [Pod Affinity Namespace Selector](/docs/concepts/scheduling-eviction/assign-pod-node/#namespace-selector)
   and [CrossNamespacePodAffinity](/docs/concepts/policy/resource-quotas/#cross-namespace-pod-affinity-quota) quota scope features.

content/en/docs/tasks/debug-application-cluster/resource-metrics-pipeline.md

@@ -65,3 +65,12 @@ Metrics Server collects metrics from the Summary API, exposed by
 
 Learn more about the metrics server in
 [the design doc](https://github.com/kubernetes/community/blob/master/contributors/design-proposals/instrumentation/metrics-server.md).
+
+### Summary API Source
+The [Kubelet](/docs/reference/command-line-tools-reference/kubelet/) gathers stats at node, volume, pod and container level, and omits
+them in the [Summary API](https://github.com/kubernetes/kubernetes/blob/7d309e0104fedb57280b261e5677d919cb2a0e2d/staging/src/k8s.io/kubelet/pkg/apis/stats/v1alpha1/types.go)
+for consumers to read.
+
+Pre-1.23, these resources have been primarily gathered from [cAdvisor](https://github.com/google/cadvisor). However, in 1.23 with the
+introduction of the `PodAndContainerStatsFromCRI` FeatureGate, container and pod level stats can be gathered by the CRI implementation.
+Note: this also requires support from the CRI implementations (containerd >= 1.6.0, CRI-O >= 1.23.0).