2.12. Using device plugins to access external resources with pods
Device plugins allow you to use a particular device type (GPU, InfiniBand, or other similar computing resources that require vendor-specific initialization and setup) in your OpenShift Container Platform pod without needing to write custom code.
2.12.1. Understanding device plugins 링크 복사링크가 클립보드에 복사되었습니다!
The device plugin provides a consistent and portable solution to consume hardware devices across clusters. The device plugin provides support for these devices through an extension mechanism, which makes these devices available to Containers, provides health checks of these devices, and securely shares them.
OpenShift Container Platform supports the device plugin API, but the device plugin Containers are supported by individual vendors.
A device plugin is a gRPC service running on the nodes (external to the kubelet) that is responsible for managing specific hardware resources. Any device plugin must support following remote procedure calls (RPCs):
service DevicePlugin {
// GetDevicePluginOptions returns options to be communicated with Device
// Manager
rpc GetDevicePluginOptions(Empty) returns (DevicePluginOptions) {}
// ListAndWatch returns a stream of List of Devices
// Whenever a Device state change or a Device disappears, ListAndWatch
// returns the new list
rpc ListAndWatch(Empty) returns (stream ListAndWatchResponse) {}
// Allocate is called during container creation so that the Device
// Plug-in can run device specific operations and instruct Kubelet
// of the steps to make the Device available in the container
rpc Allocate(AllocateRequest) returns (AllocateResponse) {}
// PreStartcontainer is called, if indicated by Device Plug-in during
// registration phase, before each container start. Device plug-in
// can run device specific operations such as resetting the device
// before making devices available to the container
rpc PreStartcontainer(PreStartcontainerRequest) returns (PreStartcontainerResponse) {}
}
2.12.1.1. Example device plugins 링크 복사링크가 클립보드에 복사되었습니다!
For easy device plugin reference implementation, there is a stub device plugin in the Device Manager code: vendor/k8s.io/kubernetes/pkg/kubelet/cm/deviceplugin/device_plugin_stub.go.
2.12.1.2. Methods for deploying a device plugin 링크 복사링크가 클립보드에 복사되었습니다!
- Daemon sets are the recommended approach for device plugin deployments.
- Upon start, the device plugin will try to create a UNIX domain socket at /var/lib/kubelet/device-plugin/ on the node to serve RPCs from Device Manager.
- Since device plugins must manage hardware resources, access to the host file system, as well as socket creation, they must be run in a privileged security context.
- More specific details regarding deployment steps can be found with each device plugin implementation.