Document Windows node support for the collector

docs/instrument/collector-setup/kubernetes-helm-setup.md

@@ -82,6 +82,92 @@ helm install scout base14/scout-collector --version 0.6.0 \
 </Tabs>
 ```
 
+## Windows Nodes
+
+:::note
+
+Windows node support is experimental. It is disabled by default, so enabling
+it is an explicit opt-in.
+
+:::
+
+If your cluster has Windows node groups, the collector needs a second DaemonSet
+to run on them. A single DaemonSet cannot serve both operating systems: the
+collector image is published separately for Linux and Windows, and the Linux
+daemon mounts Linux host paths that Windows pods do not support.
+
+### Enabling it
+
+Set this in your `values.yaml`, then install as shown above:
+
+```yaml showLineNumbers title="values.yaml"
+scout:
+  windowsDaemon:
+    enabled: true
+```
+
+The Windows daemon shares your Scout endpoint and credentials with the other
+collectors, so there is nothing further to configure.
+
+The exception is `extraEnvs`, which is per-collector: Helm replaces lists rather
+than merging them. If you supply the Scout secret through an environment
+variable rather than setting `scout.apiKey`, add the same entry under
+`windowsDaemon.extraEnvs` as well as `agent-collector.extraEnvs`.
+
+### What it collects
+
+Container logs from `C:\var\log\pods` and kubelet stats from the Windows
+kubelet.
+
+Host metrics, Windows Event Log and performance counters are not collected yet.
+
+Telemetry from applications *running on* Windows nodes does not need any of
+this — point your SDKs at the agent as usual. The service is named after your
+Helm release, so with the `helm install scout ...` above it is:
+
+```text
+scout-agent-collector.scout.svc:4318
+```
+
+### Windows Server version
+
+The default image targets **Windows Server 2022**. A Windows container image
+must match the host build, so on Server 2019 set the tag explicitly:
+
+```yaml showLineNumbers title="values.yaml"
+scout:
+  windowsDaemon:
+    enabled: true
+    image:
+      tag: "0.130.1-windows-2019-amd64"
+```
+
+A cluster with a mix of 2019 and 2022 nodes needs one DaemonSet per build, since
+a single pod template carries a single image. Contact support and we will help
+you configure it.
+
+### Other options
+
+```yaml showLineNumbers title="values.yaml"
+scout:
+  windowsDaemon:
+    enabled: true
+    # Windows node pools are often tainted; tolerate yours here.
+    tolerations: []
+    # Where the kubelet writes container logs, if your nodes differ.
+    hostLogPath: 'C:\var\log\pods'
+    # The collector runs as ContainerUser, which is not an administrator. If log
+    # collection fails with permission errors, set ContainerAdministrator.
+    runAsUserName: ""
+    resources:
+      requests:
+        memory: 128Mi
+        cpu: 100m
+      limits:
+        memory: 512Mi
+        cpu: 400m
+```
+
 ## Configuration Guide
 
 ## Using Otelcol style configuration