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Device Monitoring Documentation #9945

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Nov 27, 2018
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Device Monitoring Documentation #9945

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30 changes: 30 additions & 0 deletions content/en/docs/concepts/extend-kubernetes/compute-storage-net/device-plugins.md
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Expand Up @@ -136,6 +136,36 @@ a Kubernetes release with a newer device plugin API version, upgrade your device
to support both versions before upgrading these nodes to
ensure the continuous functioning of the device allocations during the upgrade.

## Monitoring Device Plugin Resources

In order to monitor resources provided by device plugins, monitoring agents need to be able to
discover the set of devices that are in-use on the node and obtain metadata to describe which
container the metric should be associated with. Prometheus metrics exposed by device monitoring
agents should follow the
[Kubernetes Instrumentation Guidelines](https://github.com/kubernetes/community/blob/master/contributors/devel/instrumentation.md),
which requires identifying containers using `pod`, `namespace`, and `container` prometheus labels.
The kubelet provides a gRPC service to enable discovery of in-use devices, and to provide metadata
for these devices:

```gRPC
// PodResources is a service provided by the kubelet that provides information about the
// node resources consumed by pods and containers on the node
service PodResources {
rpc List(ListPodResourcesRequest) returns (ListPodResourcesResponse) {}
}
```

The gRPC service is served over a unix socket at `/var/lib/kubelet/pod-resources/kubelet.sock`.
Monitoring agents for device plugin resources can be deployed as a daemon, or as a DaemonSet.
The cannonical directory `/var/lib/kubelet/pod-resources` requires privileged access, so monitoring
agents must run in a privileged security context. If a device monitoring agent is running as a
DaemonSet, `/var/lib/kubelet/pod-resources` must be mounted as a
[Volume](/docs/reference/generated/kubernetes-api/{{< param "version" >}}/#volume-v1-core)
in the plugin's
[PodSpec](/docs/reference/generated/kubernetes-api/{{< param "version" >}}/#podspec-v1-core).

Support for the "PodResources service" is still in alpha.

## Examples

For examples of device plugin implementations, see:
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