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

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

pkg/mgmt/zfsnode/zfsnode.go

@@ -0,0 +1,307 @@
+/*
+ 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 (
+	"fmt"
+	"reflect"
+	"time"
+
+	apis "github.com/openebs/zfs-localpv/pkg/apis/openebs.io/zfs/v1"
+	"github.com/openebs/zfs-localpv/pkg/builder/nodebuilder"
+	"github.com/openebs/zfs-localpv/pkg/equality"
+	"github.com/openebs/zfs-localpv/pkg/zfs"
+	k8serror "k8s.io/apimachinery/pkg/api/errors"
+	metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
+	"k8s.io/apimachinery/pkg/util/runtime"
+	"k8s.io/apimachinery/pkg/util/wait"
+	"k8s.io/client-go/tools/cache"
+	"k8s.io/klog"
+)
+
+func (c *NodeController) listZFSPool() ([]apis.Pool, error) {
+	return zfs.ListZFSPool()
+}
+
+// syncHandler compares the actual state with the desired, and attempts to
+// converge the two.
+func (c *NodeController) syncHandler(key string) error {
+	// Convert the namespace/name string into a distinct namespace and name
+	namespace, name, err := cache.SplitMetaNamespaceKey(key)
+	if err != nil {
+		runtime.HandleError(fmt.Errorf("invalid resource key: %s", key))
+		return nil
+	}
+
+	return c.syncNode(namespace, name)
+}
+
+// syncNode is the function which tries to converge to a desired state for the
+// ZFSNode
+func (c *NodeController) syncNode(namespace string, name string) error {
+	// Get the node resource with this namespace/name
+	cachedNode, err := c.NodeLister.ZFSNodes(namespace).Get(name)
+	if err != nil && !k8serror.IsNotFound(err) {
+		return err
+	}
+	var node *apis.ZFSNode
+	if cachedNode != nil {
+		node = cachedNode.DeepCopy()
+	}
+
+	pools, err := c.listZFSPool()
+	if err != nil {
+		return err
+	}
+
+	if node == nil { // if it doesn't exists, create zfs node object
+		if node, err = nodebuilder.NewBuilder().
+			WithNamespace(namespace).WithName(name).
+			WithPools(pools).
+			WithOwnerReferences(c.ownerRef).
+			Build(); err != nil {
+			return err
+		}
+
+		klog.Infof("zfs node controller: creating new node object for %+v", node)
+		if node, err = nodebuilder.NewKubeclient().WithNamespace(namespace).Create(node); err != nil {
+			return fmt.Errorf("create zfs node %s/%s: %v", namespace, name, err)
+		}
+		klog.Infof("zfs node controller: created node object %s/%s", namespace, name)
+		return nil
+	}
+
+	// zfs node already exists check if we need to update it.
+	var updateRequired bool
+	// validate if owner reference updated.
+	if ownerRefs, req := c.isOwnerRefsUpdateRequired(node.OwnerReferences); req {
+		klog.Infof("zfs node controller: node owner references updated current=%+v, required=%+v",
+			node.OwnerReferences, ownerRefs)
+		node.OwnerReferences = ownerRefs
+		updateRequired = true
+	}
+
+	// validate if node pools are upto date.
+	if !equality.Semantic.DeepEqual(node.Pools, pools) {
+		klog.Infof("zfs node controller: node pools updated current=%+v, required=%+v",
+			node.Pools, pools)
+		node.Pools = pools
+		updateRequired = true
+	}
+
+	if !updateRequired {
+		return nil
+	}
+
+	klog.Infof("zfs node controller: updating node object with %+v", node)
+	if _, err = nodebuilder.NewKubeclient().WithNamespace(namespace).Update(node); err != nil {
+		return fmt.Errorf("update zfs node %s/%s: %v", namespace, name, err)
+	}
+	klog.Infof("zfs node controller: updated node object %s/%s", namespace, name)
+
+	return nil
+}
+
+// addNode is the add event handler for ZFSNode
+func (c *NodeController) addNode(obj interface{}) {
+	node, ok := obj.(*apis.ZFSNode)
+	if !ok {
+		runtime.HandleError(fmt.Errorf("Couldn't get node object %#v", obj))
+		return
+	}
+
+	klog.Infof("Got add event for zfs node %s/%s", node.Namespace, node.Name)
+	c.enqueueNode(node)
+}
+
+// updateNode is the update event handler for ZFSNode
+func (c *NodeController) updateNode(oldObj, newObj interface{}) {
+	newNode, ok := newObj.(*apis.ZFSNode)
+	if !ok {
+		runtime.HandleError(fmt.Errorf("Couldn't get node object %#v", newNode))
+		return
+	}
+
+	klog.Infof("Got update event for zfs node %s/%s", newNode.Namespace, newNode.Name)
+	c.enqueueNode(newNode)
+}
+
+// deleteNode is the delete event handler for ZFSNode
+func (c *NodeController) deleteNode(obj interface{}) {
+	node, ok := obj.(*apis.ZFSNode)
+	if !ok {
+		tombstone, ok := obj.(cache.DeletedFinalStateUnknown)
+		if !ok {
+			runtime.HandleError(fmt.Errorf("Couldn't get object from tombstone %#v", obj))
+			return
+		}
+		node, ok = tombstone.Obj.(*apis.ZFSNode)
+		if !ok {
+			runtime.HandleError(fmt.Errorf("Tombstone contained object that is not a ZFSNode %#v", obj))
+			return
+		}
+	}
+
+	klog.Infof("Got delete event for node %s/%s", node.Namespace, node.Name)
+	c.enqueueNode(node)
+}
+
+// enqueueNode takes a ZFSNode resource and converts it into a namespace/name
+// string which is then put onto the work queue. This method should *not* be
+// passed resources of any type other than ZFSNode.
+func (c *NodeController) enqueueNode(node *apis.ZFSNode) {
+	// node must exists in openebs namespace & must equal to the node id.
+	if node.Namespace != zfs.OpenEBSNamespace ||
+		node.Name != zfs.NodeID {
+		klog.Warningf("skipping zfs node object %s/%s", node.Namespace, node.Name)
+		return
+	}
+
+	key, err := cache.MetaNamespaceKeyFunc(node)
+	if err != nil {
+		runtime.HandleError(err)
+		return
+	}
+	c.workqueue.Add(key)
+}
+
+// Run will set up the event handlers for types we are interested in, as well
+// as syncing informer caches and starting workers. It will block until stopCh
+// is closed, at which point it will shutdown the workqueue and wait for
+// workers to finish processing their current work items.
+func (c *NodeController) Run(threadiness int, stopCh <-chan struct{}) error {
+	defer runtime.HandleCrash()
+	defer c.workqueue.ShutDown()
+
+	// Start the informer factories to begin populating the informer caches
+	klog.Info("Starting Node controller")
+
+	// Wait for the k8s caches to be synced before starting workers
+	klog.Info("Waiting for informer caches to sync")
+	if ok := cache.WaitForCacheSync(stopCh, c.NodeSynced); !ok {
+		return fmt.Errorf("failed to wait for caches to sync")
+	}
+
+	klog.Info("Starting Node workers")
+	// Launch worker to process Node resources
+	// Threadiness will decide the number of workers you want to launch to process work items from queue
+	for i := 0; i < threadiness; i++ {
+		go wait.Until(c.runWorker, time.Second, stopCh)
+	}
+
+	klog.Info("Started Node workers")
+
+	timer := time.NewTimer(0)
+	defer timer.Stop()
+	for {
+		select {
+		case <-timer.C:
+		case <-stopCh:
+			klog.Info("Shutting down Node controller")
+			return nil
+		}
+		item := zfs.OpenEBSNamespace + "/" + zfs.NodeID
+		c.workqueue.Add(item) // add the item to worker queue.
+		timer.Reset(c.pollInterval)
+	}
+}
+
+// runWorker is a long-running function that will continually call the
+// processNextWorkItem function in order to read and process a message on the
+// workqueue.
+func (c *NodeController) runWorker() {
+	for c.processNextWorkItem() {
+	}
+}
+
+// processNextWorkItem will read a single work item off the workqueue and
+// attempt to process it, by calling the syncHandler.
+func (c *NodeController) processNextWorkItem() bool {
+	obj, shutdown := c.workqueue.Get()
+
+	if shutdown {
+		return false
+	}
+
+	// We wrap this block in a func so we can defer c.workqueue.Done.
+	err := func(obj interface{}) error {
+		// We call Done here so the workqueue knows we have finished
+		// processing this item. We also must remember to call Forget if we
+		// do not want this work item being re-queued. For example, we do
+		// not call Forget if a transient error occurs, instead the item is
+		// put back on the workqueue and attempted again after a back-off
+		// period.
+		defer c.workqueue.Done(obj)
+		var key string
+		var ok bool
+		// We expect strings to come off the workqueue. These are of the
+		// form namespace/name. We do this as the delayed nature of the
+		// workqueue means the items in the informer cache may actually be
+		// more up to date that when the item was initially put onto the
+		// workqueue.
+		if key, ok = obj.(string); !ok {
+			// As the item in the workqueue is actually invalid, we call
+			// Forget here else we'd go into a loop of attempting to
+			// process a work item that is invalid.
+			c.workqueue.Forget(obj)
+			runtime.HandleError(fmt.Errorf("expected string in workqueue but got %#v", obj))
+			return nil
+		}
+		// Run the syncHandler, passing it the namespace/name string of the
+		// Node resource to be synced.
+		if err := c.syncHandler(key); err != nil {
+			// Put the item back on the workqueue to handle any transient errors.
+			c.workqueue.AddRateLimited(key)
+			return fmt.Errorf("error syncing '%s': %s, requeuing", key, err.Error())
+		}
+		// Finally, if no error occurs we Forget this item so it does not
+		// get queued again until another change happens.
+		c.workqueue.Forget(obj)
+		klog.V(5).Infof("Successfully synced '%s'", key)
+		return nil
+	}(obj)
+
+	if err != nil {
+		runtime.HandleError(err)
+		return true
+	}
+
+	return true
+}
+
+// isOwnerRefUpdateRequired validates if relevant owner references is being
+// set for zfs node. If not, it returns the final owner references that needs
+// to be set.
+func (c *NodeController) isOwnerRefsUpdateRequired(ownerRefs []metav1.OwnerReference) ([]metav1.OwnerReference, bool) {
+	updated := false
+	reqOwnerRef := c.ownerRef
+	for idx := range ownerRefs {
+		if ownerRefs[idx].UID != reqOwnerRef.UID {
+			continue
+		}
+		// in case owner reference exists, validate
+		// if controller field is set correctly or not.
+		if !reflect.DeepEqual(ownerRefs[idx].Controller, reqOwnerRef.Controller) {
+			updated = true
+			ownerRefs[idx].Controller = reqOwnerRef.Controller
+		}
+		return ownerRefs, updated
+	}
+	updated = true
+	ownerRefs = append(ownerRefs, reqOwnerRef)
+	return ownerRefs, updated
+}