feat(scheduling): add zfs pool capacity tracking (#335)

Signed-off-by: shubham <shubham.bajpai@mayadata.io>

pkg/mgmt/zfsnode/start.go

@@ -0,0 +1,109 @@
+/*
+ Copyright © 2021 The OpenEBS Authors
+
+ Licensed under the Apache License, Version 2.0 (the "License");
+ you may not use this file except in compliance with the License.
+ You may obtain a copy of the License at
+
+     http://www.apache.org/licenses/LICENSE-2.0
+
+ Unless required by applicable law or agreed to in writing, software
+ distributed under the License is distributed on an "AS IS" BASIS,
+ WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ See the License for the specific language governing permissions and
+ limitations under the License.
+*/
+
+package zfsnode
+
+import (
+	"context"
+	"sync"
+	"time"
+
+	k8sapi "github.com/openebs/lib-csi/pkg/client/k8s"
+	clientset "github.com/openebs/zfs-localpv/pkg/generated/clientset/internalclientset"
+	informers "github.com/openebs/zfs-localpv/pkg/generated/informer/externalversions"
+	"github.com/openebs/zfs-localpv/pkg/zfs"
+	"github.com/pkg/errors"
+	metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
+	"k8s.io/apimachinery/pkg/fields"
+	"k8s.io/apimachinery/pkg/runtime/schema"
+	"k8s.io/client-go/kubernetes"
+)
+
+// Start starts the zfsnode controller.
+func Start(controllerMtx *sync.RWMutex, stopCh <-chan struct{}) error {
+
+	// Get in cluster config
+	cfg, err := k8sapi.Config().Get()
+	if err != nil {
+		return errors.Wrap(err, "error building kubeconfig")
+	}
+
+	// Building Kubernetes Clientset
+	kubeClient, err := kubernetes.NewForConfig(cfg)
+	if err != nil {
+		return errors.Wrap(err, "error building kubernetes clientset")
+	}
+
+	// Building OpenEBS Clientset
+	openebsClient, err := clientset.NewForConfig(cfg)
+	if err != nil {
+		return errors.Wrap(err, "error building openebs clientset")
+	}
+
+	// setup watch only on node we are interested in.
+	nodeInformerFactory := informers.NewSharedInformerFactoryWithOptions(
+		openebsClient, 0, informers.WithNamespace(zfs.OpenEBSNamespace),
+		informers.WithTweakListOptions(func(options *metav1.ListOptions) {
+			options.FieldSelector = fields.OneTermEqualSelector("metadata.name", zfs.NodeID).String()
+		}))
+
+	k8sNode, err := kubeClient.CoreV1().Nodes().Get(context.TODO(), zfs.NodeID, metav1.GetOptions{})
+	if err != nil {
+		return errors.Wrapf(err, "fetch k8s node %s", zfs.NodeID)
+	}
+	isTrue := true
+	// as object returned by client go clears all TypeMeta from it.
+	nodeGVK := &schema.GroupVersionKind{
+		Group: "", Version: "v1", Kind: "Node",
+	}
+	ownerRef := metav1.OwnerReference{
+		APIVersion: nodeGVK.GroupVersion().String(),
+		Kind:       nodeGVK.Kind,
+		Name:       k8sNode.Name,
+		UID:        k8sNode.GetUID(),
+		Controller: &isTrue,
+	}
+
+	// Build() fn of all controllers calls AddToScheme to adds all types of this
+	// clientset into the given scheme.
+	// If multiple controllers happen to call this AddToScheme same time,
+	// it causes panic with error saying concurrent map access.
+	// This lock is used to serialize the AddToScheme call of all controllers.
+	controllerMtx.Lock()
+
+	controller, err := NewNodeControllerBuilder().
+		withKubeClient(kubeClient).
+		withOpenEBSClient(openebsClient).
+		withNodeSynced(nodeInformerFactory).
+		withNodeLister(nodeInformerFactory).
+		withRecorder(kubeClient).
+		withEventHandler(nodeInformerFactory).
+		withPollInterval(60 * time.Second).
+		withOwnerReference(ownerRef).
+		withWorkqueueRateLimiting().Build()
+
+	// blocking call, can't use defer to release the lock
+	controllerMtx.Unlock()
+
+	if err != nil {
+		return errors.Wrapf(err, "error building controller instance")
+	}
+
+	nodeInformerFactory.Start(stopCh)
+
+	// Threadiness defines the number of workers to be launched in Run function
+	return controller.Run(1, stopCh)
+}