add topology aware provisioning for controller service

src/csi/backend/backend.go

@@ -4,12 +4,18 @@ import (
 	"csi/backend/plugin"
 	"errors"
 	"fmt"
+	"math/rand"
 	"regexp"
 	"sync"
 	"utils"
 	"utils/log"
 )
 
+const (
+	TopologyRequirement = "topologyRequirement"
+	SupportedTopologies = "supportedTopologies"
+)
+
 var (
 	mutex       sync.Mutex
 	csiBackends = make(map[string]*Backend)
@@ -22,6 +28,7 @@ var (
 		{"qos", filterByQos},
 		{"hyperMetro", filterByMetro},
 		{"replication", filterByReplication},
+		{"topologyRequirement", filterByTopology},
 	}
 
 	secondaryFilterFuncs = [][]interface{}{
@@ -32,6 +39,13 @@ var (
 	}
 )
 
+type FilterFunction func(interface{}, []*StoragePool) []*StoragePool
+
+type AccessibleTopology struct {
+	RequisiteTopologies []map[string]string
+	PreferredTopologies []map[string]string
+}
+
 type StoragePool struct {
 	Name         string
 	Storage      string
@@ -41,12 +55,13 @@ type StoragePool struct {
 }
 
 type Backend struct {
-	Name       string
-	Storage    string
-	Available  bool
-	Plugin     plugin.Plugin
-	Pools      []*StoragePool
-	Parameters map[string]interface{}
+	Name                string
+	Storage             string
+	Available           bool
+	Plugin              plugin.Plugin
+	Pools               []*StoragePool
+	Parameters          map[string]interface{}
+	SupportedTopologies []map[string]string
 
 	MetroDomain       string
 	MetrovStorePairID string
@@ -109,6 +124,11 @@ func newBackend(backendName string, config map[string]interface{}) (*Backend, er
 		return nil, errors.New("parameters must be configured for backend")
 	}
 
+	supportedTopologies, exists := config[SupportedTopologies].([]map[string]string)
+	if !exists {
+		return nil, errors.New("invalid supportedTopologies configured for backend")
+	}
+
 	plugin := plugin.GetPlugin(storage)
 	if plugin == nil {
 		return nil, fmt.Errorf("Cannot get plugin for storage %s", storage)
@@ -126,15 +146,16 @@ func newBackend(backendName string, config map[string]interface{}) (*Backend, er
 	}
 
 	return &Backend{
-		Name:               backendName,
-		Storage:            storage,
-		Available:          false,
-		Plugin:             plugin,
-		Parameters:         parameters,
-		MetroDomain:        metroDomain,
-		MetrovStorePairID:  metrovStorePairID,
-		ReplicaBackendName: replicaBackend,
-		MetroBackendName:   metroBackend,
+		Name:                backendName,
+		Storage:             storage,
+		Available:           false,
+		SupportedTopologies: supportedTopologies,
+		Plugin:              plugin,
+		Parameters:          parameters,
+		MetroDomain:         metroDomain,
+		MetrovStorePairID:   metrovStorePairID,
+		ReplicaBackendName:  replicaBackend,
+		MetroBackendName:    metroBackend,
 	}, nil
 }
 
@@ -269,7 +290,7 @@ func selectOnePool(requestSize int64,
 	}
 
 	for _, i := range filterFuncs {
-		key, filter := i[0].(string), i[1].(func(string, []*StoragePool) []*StoragePool)
+		key, filter := i[0].(string), i[1].(FilterFunction)
 		value, _ := parameters[key].(string)
 		filterPools = filter(value, filterPools)
 		if len(filterPools) == 0 {
@@ -354,9 +375,14 @@ func SelectStoragePool(requestSize int64, parameters map[string]interface{}) (*S
 	return localPool, remotePool, nil
 }
 
-func filterByBackendName(backendName string, candidatePools []*StoragePool) []*StoragePool {
+func filterByBackendName(iBackendName interface{}, candidatePools []*StoragePool) []*StoragePool {
 	var filterPools []*StoragePool
 
+	backendName, ok := iBackendName.(string)
+	if !ok {
+		return candidatePools
+	}
+
 	for _, pool := range candidatePools {
 		if backendName == "" || backendName == pool.Parent {
 			filterPools = append(filterPools, pool)
@@ -366,9 +392,14 @@ func filterByBackendName(backendName string, candidatePools []*StoragePool) []*S
 	return filterPools
 }
 
-func filterByStoragePool(poolName string, candidatePools []*StoragePool) []*StoragePool {
+func filterByStoragePool(iPoolName interface{}, candidatePools []*StoragePool) []*StoragePool {
 	var filterPools []*StoragePool
 
+	poolName, ok := iPoolName.(string)
+	if !ok {
+		return candidatePools
+	}
+
 	for _, pool := range candidatePools {
 		if poolName == "" || poolName == pool.Name {
 			filterPools = append(filterPools, pool)
@@ -378,9 +409,14 @@ func filterByStoragePool(poolName string, candidatePools []*StoragePool) []*Stor
 	return filterPools
 }
 
-func filterByVolumeType(volumeType string, candidatePools []*StoragePool) []*StoragePool {
+func filterByVolumeType(iVolumeType interface{}, candidatePools []*StoragePool) []*StoragePool {
 	var filterPools []*StoragePool
 
+	volumeType, ok := iVolumeType.(string)
+	if !ok {
+		return candidatePools
+	}
+
 	for _, pool := range candidatePools {
 		if volumeType == "lun" || volumeType == "" {
 			if pool.Storage == "oceanstor-san" || pool.Storage == "fusionstorage-san" {
@@ -396,9 +432,14 @@ func filterByVolumeType(volumeType string, candidatePools []*StoragePool) []*Sto
 	return filterPools
 }
 
-func filterByAllocType(allocType string, candidatePools []*StoragePool) []*StoragePool {
+func filterByAllocType(iAllocType interface{}, candidatePools []*StoragePool) []*StoragePool {
 	var filterPools []*StoragePool
 
+	allocType, ok := iAllocType.(string)
+	if !ok {
+		return candidatePools
+	}
+
 	for _, pool := range candidatePools {
 		valid := false
 
@@ -420,9 +461,14 @@ func filterByAllocType(allocType string, candidatePools []*StoragePool) []*Stora
 	return filterPools
 }
 
-func filterByQos(qos string, candidatePools []*StoragePool) []*StoragePool {
+func filterByQos(iqos interface{}, candidatePools []*StoragePool) []*StoragePool {
 	var filterPools []*StoragePool
 
+	qos, ok := iqos.(string)
+	if !ok {
+		return candidatePools
+	}
+
 	for _, pool := range candidatePools {
 		if qos != "" {
 			supportQoS, exist := pool.Capabilities["SupportQoS"].(bool)
@@ -437,8 +483,9 @@ func filterByQos(qos string, candidatePools []*StoragePool) []*StoragePool {
 	return filterPools
 }
 
-func filterByMetro(hyperMetro string, candidatePools []*StoragePool) []*StoragePool {
-	if len(hyperMetro) == 0 || !utils.StrToBool(hyperMetro) {
+func filterByMetro(iHyperMetro interface{}, candidatePools []*StoragePool) []*StoragePool {
+	hyperMetro, ok := iHyperMetro.(string)
+	if !ok || len(hyperMetro) == 0 || !utils.StrToBool(hyperMetro) {
 		return candidatePools
 	}
 
@@ -458,8 +505,9 @@ func filterByMetro(hyperMetro string, candidatePools []*StoragePool) []*StorageP
 	return filterPools
 }
 
-func filterByReplication(replication string, candidatePools []*StoragePool) []*StoragePool {
-	if len(replication) == 0 || !utils.StrToBool(replication) {
+func filterByReplication(iReplication interface{}, candidatePools []*StoragePool) []*StoragePool {
+	replication, ok := iReplication.(string)
+	if !ok || len(replication) == 0 || !utils.StrToBool(replication) {
 		return candidatePools
 	}
 
@@ -478,3 +526,111 @@ func filterByReplication(replication string, candidatePools []*StoragePool) []*S
 
 	return filterPools
 }
+
+// filterByTopology returns a subset of the provided pools that can support any of the topology requirement.
+func filterByTopology(iTopologyRequirement interface{}, candidatePools []*StoragePool) []*StoragePool {
+	topologyRequirement, ok := iTopologyRequirement.(AccessibleTopology)
+	if !ok || len(topologyRequirement.RequisiteTopologies) == 0 {
+		return candidatePools
+	}
+
+	filterPools := filterPoolsOnTopology(candidatePools, topologyRequirement.RequisiteTopologies)
+	if len(filterPools) == 0 {
+		log.Infoln("no backend pools support any requisite topologies")
+	}
+	return sortPoolsByPreferredTopologies(filterPools, topologyRequirement.PreferredTopologies)
+}
+
+// isTopologySupportedByBackend returns whether the specific backend can create volumes accessible by the given topology
+func isTopologySupportedByBackend(backend *Backend, topology map[string]string) bool {
+	requisiteFound := false
+	for _, supported := range backend.SupportedTopologies {
+		eachFound := true
+		for k, v := range topology {
+			if sup, ok := supported[k]; ok && sup != v {
+				eachFound = false
+				break
+			}
+		}
+		if eachFound {
+			requisiteFound = true
+		}
+	}
+	return requisiteFound
+}
+
+// filterPoolsOnTopology returns a subset of the provided pools that can support any of the requisiteTopologies.
+func filterPoolsOnTopology(candidatePools []*StoragePool, requisiteTopologies []map[string]string) []*StoragePool {
+	filteredPools := make([]*StoragePool, 0)
+
+	if len(requisiteTopologies) == 0 {
+		return candidatePools
+	}
+
+	for _, pool := range candidatePools {
+		backend, exist := csiBackends[pool.Parent]
+		if !exist {
+			continue
+		}
+
+		if len(backend.SupportedTopologies) > 0 {
+			for _, topology := range requisiteTopologies {
+				if isTopologySupportedByBackend(backend, topology) {
+					filteredPools = append(filteredPools, pool)
+					break
+				}
+			}
+		} else {
+			filteredPools = append(filteredPools, pool)
+		}
+	}
+
+	return filteredPools
+}
+
+// sortPoolsByPreferredTopologies returns a list of pools ordered by the pools supportedTopologies field against
+// the provided list of preferredTopologies. If 2 or more pools can support a given preferredTopology, they are shuffled
+// randomly within that segment of the list, in order to prevent hotspots.
+func sortPoolsByPreferredTopologies(candidatePools []*StoragePool, preferredTopologies []map[string]string) []*StoragePool {
+	remainingPools := make([]*StoragePool, len(candidatePools))
+	copy(remainingPools, candidatePools)
+	orderedPools := make([]*StoragePool, 0)
+
+	for _, preferred := range preferredTopologies {
+
+		newRemainingPools := make([]*StoragePool, 0)
+		poolBucket := make([]*StoragePool, 0)
+
+		for _, pool := range remainingPools {
+			backend, exist := csiBackends[pool.Parent]
+			if !exist {
+				continue
+			}
+			// If it supports topology, pop it and add to bucket. Otherwise, add it to newRemaining pools to be
+			// addressed in future loop iterations.
+			if isTopologySupportedByBackend(backend, preferred) {
+				poolBucket = append(poolBucket, pool)
+			} else {
+				newRemainingPools = append(newRemainingPools, pool)
+			}
+		}
+
+		// make new list of remaining pools
+		remainingPools = make([]*StoragePool, len(newRemainingPools))
+		copy(remainingPools, newRemainingPools)
+
+		// shuffle bucket
+		rand.Shuffle(len(poolBucket), func(i, j int) {
+			poolBucket[i], poolBucket[j] = poolBucket[j], poolBucket[i]
+		})
+
+		// add all in bucket to final list
+		orderedPools = append(orderedPools, poolBucket...)
+	}
+
+	// shuffle and add leftover pools the did not match any preference
+	rand.Shuffle(len(remainingPools), func(i, j int) {
+		remainingPools[i], remainingPools[j] = remainingPools[j], remainingPools[i]
+	})
+	return append(orderedPools, remainingPools...)
+}