Add documentation for the Kubelet Stats receiver (kubeletstatsreceiver) (#11191)

* Add documentation for the Kubelet Stats receiver (kubeletstatsreceiver)

* Minor changes to adhere to Elastic's docs style guide and tone of voice

* Add component to toc

* Apply comments

Author: alexandra5000

docs/reference/edot-collector/components/kubeletstatsreceiver.md

@@ -0,0 +1,120 @@
+---
+navigation_title: Kubelet stats receiver
+description: The Kubelet stats receiver is an OpenTelemetry Collector component that collects node, pod, container, and volume resource metrics from the Kubernetes Kubelet.
+applies_to:
+  stack:
+  serverless:
+    observability:
+  product:
+    edot_collector:
+products:
+  - id: cloud-serverless
+  - id: observability
+  - id: edot-collector
+---
+
+# Kubelet stats receiver
+
+The Kubelet stats receiver collects Kubernetes node, pod, container, and volume metrics directly from the Kubelet API. It is enabled by default in several {{product.observability}} Kubernetes pipelines and is a core component of the {{edot}} Collector distribution.
+
+This receiver queries the Kubelet's `/stats/summary` endpoint and converts the retrieved usage statistics into OpenTelemetry metrics. When configured, it automatically surfaces pre-built dashboards in {{product.observability}} for visualizing node CPU and memory usage, pod throttling, container metrics, and network/filesystem usage.
+
+For full contrib details, refer to the [OpenTelemetry kubeletstats receiver documentation](https://github.com/open-telemetry/opentelemetry-collector-contrib/tree/main/receiver/kubeletstatsreceiver).
+
+## Typical use cases
+
+Use the Kubelet stats receiver when you need:
+
+* CPU, memory, network, and filesystem metrics for Kubernetes nodes.
+
+* Fine-grained container CPU/memory usage for workloads running on each node.
+
+* Filesystem and ephemeral storage usage for pods and containers.
+
+* To combine node- and pod-level metrics with logs and traces to troubleshoot performance issues, resource saturation, and pod eviction behavior.
+
+## Configuration
+
+The following example shows a minimal Kubelet stats receiver configuration in an EDOT Collector pipeline.
+
+```yaml
+receivers:
+  kubeletstats:
+    auth_type: serviceAccount
+    collection_interval: 30s
+    endpoint: "${KUBELET_ENDPOINT}"        # for example: https://$NODE_IP:10250
+    insecure_skip_verify: true             # or configure proper TLS
+    metric_groups:
+      - node
+      - pod
+      - container
+      - volume
+
+processors:
+  batch: {}
+
+exporters:
+  otlp:
+    endpoint: ${OTEL_EXPORTER_OTLP_ENDPOINT}
+
+service:
+  pipelines:
+    metrics:
+      receivers: [kubeletstats]
+      processors: [batch]
+      exporters: [otlp]
+```
+
+### Key configuration options
+
+The following configuration parameters determine how the Kubelet stats receiver interacts with the Kubelet API and which metric groups are collected:
+
+| Setting | Description |
+|--------|-------------|
+| `auth_type` | Authentication mechanism for talking to the Kubelet. Typically `serviceAccount` when the Collector runs as a DaemonSet. |
+| `endpoint` | The Kubelet’s secure API endpoint, usually `https://<node-ip>:10250`. |
+| `collection_interval` | How frequently the receiver scrapes Kubelet metrics. |
+| `metric_groups` | Controls which metric groups to collect (`node`, `pod`, `container`, `volume`). |
+| `insecure_skip_verify` | Whether to skip TLS certificate verification. For production, configure proper TLS if possible. |
+
+For all available settings, refer to the [contrib configuration documentation](https://github.com/open-telemetry/opentelemetry-collector-contrib/tree/main/receiver/kubeletstatsreceiver#configuration).
+
+## How it works in the EDOT Collector
+
+In EDOT, the Kubelet stats receiver is typically used when:
+
+* The Collector is deployed as a DaemonSet, scraping each node’s Kubelet locally.
+* You want per-node and per-pod usage metrics without installing additional agents.
+* The `kubernetes` or `system` metrics pipelines need pod-level resource context.
+
+EDOT applies no custom modifications to the contrib receiver (its behavior is identical to contrib). It is pre-included and validated as supported within the EDOT distribution.
+
+## Example: Collect node and pod metrics in Kubernetes
+
+When you run the EDOT Collector as a DaemonSet, you can enable the Kubelet stats receiver with a minimal configuration like this:
+
+```yaml
+receivers:
+  kubeletstats:
+    auth_type: serviceAccount
+    metric_groups: [node, pod, container]
+```
+
+This configuration collects:
+
+* Node CPU and memory usage  
+* Pod throttling  
+* Container memory working set  
+* Network and filesystem usage per node, pod, and container
+
+## Caveats and limitations
+
+Consider the following when deploying the Kubelet stats receiver:
+
+* RBAC and TLS must be configured properly. When running as a DaemonSet, the service account usually has the needed permissions.
+
+* Very low `collection_interval` values can increase Kubelet load.
+
+* Metrics for ephemeral containers may not always appear depending on underlying Kubernetes version behavior.
+
+* The receiver scrapes only the local node’s Kubelet when running as a DaemonSet. For centralized scraping, you must expose each node’s Kubelet securely (not recommended).

docs/reference/edot-collector/toc.yml

@@ -22,6 +22,7 @@ toc:
       - file: components/filelogreceiver.md
       - file: components/k8sobjectsreceiver.md
       - file: components/hostmetricsreceiver.md
+      - file: components/kubeletstatsreceiver.md
   - file: customization.md
     children:
       - file: custom-collector.md