Propagate node labels to the K8s API

Author: pmundt

README.md

@@ -1,9 +1,18 @@
 # Device Tree Kubernetes Node Labeller
 
-This tool automatically labels nodes with [devicetree] properties, useful for targeted deployments into hybrid
-Kubernetes clusters, as well as for targeting heterogeneous accelerator resources in Edge deployments.
+This tool provides a custom Kubernetes controller for automatically labelling nodes with [devicetree] properties.
 
-[devicetree]: https://www.devicetree.org
+It is inspired by and re-uses much of the Kubernetes controller plumbing from the [amdgpu-node-labeller].
+
+## Use Cases
+
+`k8s-dt-node-labeller` was developed in order to facilitate targeted deployments into hybrid (e.g. armhf, arm64)
+Kubernetes clusters, as well as for targeting heterogeneous accelerators in Edge deployments.
+
+## Usage
+
+The node labeller is further expected to be run node-local, and will need to be invoked on each individual node
+requiring its own specific devicetree parsing and labelling.
 
 By default, `compatible` strings from the top-level `/` node are discovered and converted to node labels.
 
@@ -15,7 +24,7 @@ beta.devicetree.org/nvidia-jetson-nano: 1
 beta.devicetree.org/nvidia-tegra210: 1
 ```
 
-node specifications are possible via the `-n` flag, as below:
+additional node specifications are possible via the `-n` flag, as below:
 
 ```
 $ k8s-dt-node-labeller -n gpu pwm-fan
@@ -33,9 +42,11 @@ beta.devicetree.org/pwm-fan: 1
 This project has received funding from the European Union’s Horizon 2020 research and innovation programme under grant
 agreement No 825480 ([SODALITE]).
 
-[SODALITE]: https://www.sodalite.eu
-
 ## License
 
 `k8s-dt-node-labeller` is licensed under the terms of the Apache 2.0 license, the full
 version of which can be found in the LICENSE file included in the distribution.
+
+[devicetree]: https://www.devicetree.org
+[SODALITE]: https://www.sodalite.eu
+[amdgpu-node-labeller]: https://github.com/RadeonOpenCompute/k8s-device-plugin/tree/master/cmd/k8s-node-labeller

controller.go

@@ -0,0 +1,62 @@
+package main
+
+import (
+	"context"
+
+	"github.com/go-logr/logr"
+
+	corev1 "k8s.io/api/core/v1"
+	"k8s.io/apimachinery/pkg/api/errors"
+	"sigs.k8s.io/controller-runtime/pkg/client"
+	"sigs.k8s.io/controller-runtime/pkg/reconcile"
+)
+
+type reconcileNodeLabels struct {
+	client client.Client
+	log    logr.Logger
+	labels map[string]string
+}
+
+// make sure reconcileNodeLabels implement the Reconciler interface
+var _ reconcile.Reconciler = &reconcileNodeLabels{}
+
+func (r *reconcileNodeLabels) Reconcile(request reconcile.Request) (reconcile.Result, error) {
+	// set up a convinient log object so we don't have to type request over and over again
+	log := r.log.WithValues("request", request)
+
+	node := &corev1.Node{}
+	err := r.client.Get(context.TODO(), request.NamespacedName, node)
+	if errors.IsNotFound(err) {
+		log.Error(nil, "Could not find Node")
+		return reconcile.Result{}, nil
+	}
+
+	if err != nil {
+		log.Error(err, "Could not fetch Node")
+		return reconcile.Result{}, err
+	}
+
+	// Set the label
+	if node.Labels == nil {
+		node.Labels = map[string]string{}
+	}
+
+	// Remove old labels
+	for k := range node.Labels {
+		if matchesLabelPrefix(k) {
+			delete(node.Labels, k)
+		}
+	}
+
+	for k, v := range r.labels {
+		node.Labels[k] = v
+	}
+
+	err = r.client.Update(context.TODO(), node)
+	if err != nil {
+		log.Error(err, "Could not write Node")
+		return reconcile.Result{}, err
+	}
+
+	return reconcile.Result{}, nil
+}

go.mod

@@ -2,4 +2,10 @@ module k8s-dt-node-labeller
 
 go 1.14
 
-require github.com/platinasystems/fdt v1.0.1
+require (
+	github.com/go-logr/logr v0.1.0
+	github.com/platinasystems/fdt v1.0.1
+	k8s.io/api v0.18.0
+	k8s.io/apimachinery v0.18.0
+	sigs.k8s.io/controller-runtime v0.5.2
+)