feat(schd): adding capacity weighted scheduler (#20)

Signed-off-by: Akhil Mohan <[email protected]>

changelogs/unreleased/20-akhilerm

@@ -0,0 +1 @@
+add capacity weighted scheduler and make it default for scheduling volumes

pkg/driver/schd_helper.go

@@ -17,21 +17,25 @@ limitations under the License.
 package driver
 
 import (
-	"github.com/openebs/lvm-localpv/pkg/builder/volbuilder"
 	metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
+	"strconv"
 
+	"github.com/openebs/lvm-localpv/pkg/builder/volbuilder"
 	"github.com/openebs/lvm-localpv/pkg/lvm"
 )
 
 // scheduling algorithm constants
 const (
 	// pick the node where less volumes are provisioned for the given volume group
-	// this will be the default scheduler when none provided
 	VolumeWeighted = "VolumeWeighted"
+
+	// pick the node where total provisioned volumes have occupied less capacity from the given volume group
+	// this will be the default scheduler when none provided
+	CapacityWeighted = "CapacityWeighted"
 )
 
 // getVolumeWeightedMap goes through all the volumegroup on all the nodes
-// and creats the node mapping of the volume for all the nodes.
+// and creates the node mapping of the volume for all the nodes.
 // It returns a map which has nodes as key and volumes present
 // on the nodes as corresponding value.
 func getVolumeWeightedMap(vg string) (map[string]int64, error) {
@@ -56,12 +60,44 @@ func getVolumeWeightedMap(vg string) (map[string]int64, error) {
 	return nmap, nil
 }
 
+// getCapacityWeightedMap goes through all the volume groups on all the nodes
+// and creates the node mapping of the capacity for all the nodes.
+// It returns a map which has nodes as key and capacity provisioned
+// on the nodes as corresponding value. The scheduler will use this map
+// and picks the node which is less weighted.
+func getCapacityWeightedMap(vg string) (map[string]int64, error) {
+	nmap := map[string]int64{}
+
+	volList, err := volbuilder.NewKubeclient().
+		WithNamespace(lvm.LvmNamespace).
+		List(metav1.ListOptions{})
+
+	if err != nil {
+		return nmap, err
+	}
+
+	// create the map of the volume capacity
+	// for the given volume group
+	for _, vol := range volList.Items {
+		if vol.Spec.VolGroup == vg {
+			volSize, err := strconv.ParseInt(vol.Spec.Capacity, 10, 64)
+			if err == nil {
+				nmap[vol.Spec.OwnerNodeID] += volSize
+			}
+		}
+	}
+
+	return nmap, nil
+}
+
 // getNodeMap returns the node mapping for the given scheduling algorithm
 func getNodeMap(schd string, vg string) (map[string]int64, error) {
 	switch schd {
 	case VolumeWeighted:
 		return getVolumeWeightedMap(vg)
+	case CapacityWeighted:
+		return getCapacityWeightedMap(vg)
 	}
-	// return VolumeWeighted(default) if not specified
-	return getVolumeWeightedMap(vg)
+	// return CapacityWeighted(default) if not specified
+	return getCapacityWeightedMap(vg)
 }