feat(admin): add a new flag replica-selector to the varlogadm

It added a new flag, `replica-selector`, to the varlogadm. The flag sets the global default replica
selector.

Updates #393

cmd/varlogadm/cli.go

@@ -40,6 +40,7 @@ func newStartCommand() *cli.Command {
 			flagLogStreamGCTimeout.DurationFlag(false, admin.DefaultLogStreamGCTimeout),
 			flagDisableAutoLogStreamSync.BoolFlag(),
 			flagAutoUnseal.BoolFlag(),
+			flagReplicaSelector,
 
 			flagMetadataRepository.StringSliceFlag(true, nil),
 			flagInitMRConnRetryCount.IntFlag(false, mrmanager.DefaultInitialMRConnectRetryCount),
@@ -95,10 +96,17 @@ func start(c *cli.Context) error {
 		return err
 	}
 
+	repfactor := c.Uint(flagReplicationFactor.Name)
+	repsel, err := admin.NewReplicaSelector(c.String(flagReplicaSelector.Name), mrMgr.ClusterMetadataView(), int(repfactor))
+	if err != nil {
+		return err
+	}
+
 	opts := []admin.Option{
 		admin.WithLogger(logger),
 		admin.WithListenAddress(c.String(flagListen.Name)),
-		admin.WithReplicationFactor(c.Uint(flagReplicationFactor.Name)),
+		admin.WithReplicationFactor(repfactor),
+		admin.WithReplicaSelector(repsel),
 		admin.WithLogStreamGCTimeout(c.Duration(flagLogStreamGCTimeout.Name)),
 		admin.WithMetadataRepositoryManager(mrMgr),
 		admin.WithStorageNodeManager(snMgr),

cmd/varlogadm/flags.go

@@ -1,6 +1,11 @@
 package main
 
 import (
+	"strings"
+
+	"github.com/urfave/cli/v2"
+
+	"github.com/kakao/varlog/internal/admin"
 	"github.com/kakao/varlog/internal/flags"
 )
 
@@ -30,6 +35,13 @@ var (
 		Aliases: []string{"enable-auto-unseal", "with-auto-unseal"},
 		Envs:    []string{"AUTO_UNSEAL", "ENABLE_AUTO_UNSEAL", "WITH_AUTO_UNSEAL"},
 	}
+	flagReplicaSelector = &cli.StringFlag{
+		Name:    "replica-selector",
+		Aliases: []string{"repsel"},
+		EnvVars: []string{"REPLICA_SELECTOR"},
+		Value:   admin.ReplicaSelectorNameLFU,
+		Usage:   strings.Join([]string{admin.ReplicaSelectorNameRandom, admin.ReplicaSelectorNameLFU}, " | "),
+	}
 
 	flagInitMRConnRetryCount = flags.FlagDesc{
 		Name:  "init-mr-conn-retry-count",

internal/admin/admin.go

@@ -135,6 +135,15 @@ func (adm *Admin) Serve() error {
 	}
 	adm.mu.Unlock()
 
+	if ce := adm.logger.Check(zap.InfoLevel, "starting"); ce != nil {
+		ce.Write(
+			zap.String("address", adm.serverAddr),
+			zap.Uint("replicationFactor", adm.replicationFactor),
+			zap.String("replicationSelector", adm.snSelector.Name()),
+			zap.Duration("logStreamGCTimeout", adm.logStreamGCTimeout),
+		)
+	}
+
 	return adm.server.Serve(lis)
 }
 

internal/admin/config.go

@@ -81,7 +81,7 @@ func (cfg config) validate() error {
 
 func (cfg *config) ensureDefault() error {
 	if cfg.snSelector == nil {
-		rs, err := newReplicaSelector(replicaSelectorNameLFU, cfg.mrmgr.ClusterMetadataView(), int(cfg.replicationFactor))
+		rs, err := NewReplicaSelector(ReplicaSelectorNameLFU, cfg.mrmgr.ClusterMetadataView(), int(cfg.replicationFactor))
 		if err != nil {
 			return err
 		}

internal/admin/replica_selector.go

@@ -31,11 +31,11 @@ type ReplicaSelector interface {
 }
 
 const (
-	replicaSelectorNameRandom = "random"
-	replicaSelectorNameLFU    = "lfu" // least frequently used
+	ReplicaSelectorNameRandom = "random"
+	ReplicaSelectorNameLFU    = "lfu" // least frequently used
 )
 
-func newReplicaSelector(selector string, cmview mrmanager.ClusterMetadataView, repfactor int) (ReplicaSelector, error) {
+func NewReplicaSelector(selector string, cmview mrmanager.ClusterMetadataView, repfactor int) (ReplicaSelector, error) {
 	if repfactor < 1 {
 		return nil, errors.Wrap(verrors.ErrInvalid, "replica selector: negative replication factor")
 	}
@@ -45,9 +45,9 @@ func newReplicaSelector(selector string, cmview mrmanager.ClusterMetadataView, r
 	}
 
 	switch strings.ToLower(selector) {
-	case replicaSelectorNameRandom:
+	case ReplicaSelectorNameRandom:
 		return newRandomReplicaSelector(cmview, repfactor)
-	case replicaSelectorNameLFU:
+	case ReplicaSelectorNameLFU:
 		return newLFUSelector(cmview, repfactor)
 	default:
 		return nil, fmt.Errorf("unknown selector: %s", selector)
@@ -72,7 +72,7 @@ func newRandomReplicaSelector(cmview mrmanager.ClusterMetadataView, repfactor in
 }
 
 func (s *randomReplicaSelector) Name() string {
-	return replicaSelectorNameRandom
+	return ReplicaSelectorNameRandom
 }
 
 func (s *randomReplicaSelector) Select(ctx context.Context) ([]*varlogpb.ReplicaDescriptor, error) {
@@ -131,7 +131,7 @@ func newLFUSelector(cmview mrmanager.ClusterMetadataView, repfactor int) (*lfuSe
 }
 
 func (s *lfuSelector) Name() string {
-	return replicaSelectorNameLFU
+	return ReplicaSelectorNameLFU
 }
 
 func (s *lfuSelector) Select(ctx context.Context) ([]*varlogpb.ReplicaDescriptor, error) {

internal/admin/replica_selector_test.go

@@ -21,7 +21,7 @@ func TestReplicaSelector_NewUnknown(t *testing.T) {
 	cmview := mrmanager.NewMockClusterMetadataView(ctrl)
 	cmview.EXPECT().ClusterMetadata(gomock.Any()).Return(&varlogpb.MetadataDescriptor{}, nil).AnyTimes()
 
-	_, err := newReplicaSelector("foo", cmview, 1)
+	_, err := NewReplicaSelector("foo", cmview, 1)
 	require.Error(t, err)
 
 }
@@ -34,8 +34,8 @@ func TestReplicaSelector_New(t *testing.T) {
 	cmview.EXPECT().ClusterMetadata(gomock.Any()).Return(&varlogpb.MetadataDescriptor{}, nil).AnyTimes()
 
 	selectors := []string{
-		replicaSelectorNameRandom,
-		replicaSelectorNameLFU,
+		ReplicaSelectorNameRandom,
+		ReplicaSelectorNameLFU,
 	}
 	tcs := []struct {
 		name      string
@@ -57,7 +57,7 @@ func TestReplicaSelector_New(t *testing.T) {
 	for _, tc := range tcs {
 		for _, selector := range selectors {
 			t.Run(selector+tc.name, func(t *testing.T) {
-				_, err := newReplicaSelector(selector, tc.cmview, tc.repfactor)
+				_, err := NewReplicaSelector(selector, tc.cmview, tc.repfactor)
 				require.Error(t, err)
 			})
 		}
@@ -102,7 +102,7 @@ func TestReplicaSelector(t *testing.T) {
 	tcs := []*testCase{
 		{
 			name:      "NotEnoughStorageNodes",
-			selectors: []string{replicaSelectorNameRandom, replicaSelectorNameLFU},
+			selectors: []string{ReplicaSelectorNameRandom, ReplicaSelectorNameLFU},
 			repfactor: 1,
 			md:        &varlogpb.MetadataDescriptor{},
 			testf: func(t *testing.T, _ *testCase, s ReplicaSelector) {
@@ -112,7 +112,7 @@ func TestReplicaSelector(t *testing.T) {
 		},
 		{
 			name:      "InvalidClusterMetadataInvalidStorageNodeID",
-			selectors: []string{replicaSelectorNameRandom, replicaSelectorNameLFU},
+			selectors: []string{ReplicaSelectorNameRandom, ReplicaSelectorNameLFU},
 			repfactor: 1,
 			md: &varlogpb.MetadataDescriptor{
 				StorageNodes: []*varlogpb.StorageNodeDescriptor{
@@ -130,7 +130,7 @@ func TestReplicaSelector(t *testing.T) {
 		},
 		{
 			name:      "InvalidClusterMetadataNoStoragePath",
-			selectors: []string{replicaSelectorNameRandom, replicaSelectorNameLFU},
+			selectors: []string{ReplicaSelectorNameRandom, ReplicaSelectorNameLFU},
 			repfactor: 1,
 			md: &varlogpb.MetadataDescriptor{
 				StorageNodes: []*varlogpb.StorageNodeDescriptor{
@@ -148,7 +148,7 @@ func TestReplicaSelector(t *testing.T) {
 		},
 		{
 			name:      "InvalidClusterMetadataNoStorageNode",
-			selectors: []string{replicaSelectorNameLFU},
+			selectors: []string{ReplicaSelectorNameLFU},
 			repfactor: 1,
 			md: &varlogpb.MetadataDescriptor{
 				StorageNodes: []*varlogpb.StorageNodeDescriptor{
@@ -177,7 +177,7 @@ func TestReplicaSelector(t *testing.T) {
 		},
 		{
 			name:      "InvalidClusterMetadataNoStorageNodePath",
-			selectors: []string{replicaSelectorNameLFU},
+			selectors: []string{ReplicaSelectorNameLFU},
 			repfactor: 1,
 			md: &varlogpb.MetadataDescriptor{
 				StorageNodes: []*varlogpb.StorageNodeDescriptor{
@@ -206,7 +206,7 @@ func TestReplicaSelector(t *testing.T) {
 		},
 		{
 			name:      "Select",
-			selectors: []string{replicaSelectorNameRandom},
+			selectors: []string{ReplicaSelectorNameRandom},
 			repfactor: 2,
 			md: &varlogpb.MetadataDescriptor{
 				StorageNodes: []*varlogpb.StorageNodeDescriptor{
@@ -246,7 +246,7 @@ func TestReplicaSelector(t *testing.T) {
 		},
 		{
 			name:      "Select",
-			selectors: []string{replicaSelectorNameLFU},
+			selectors: []string{ReplicaSelectorNameLFU},
 			repfactor: 3,
 			md: &varlogpb.MetadataDescriptor{
 				StorageNodes: []*varlogpb.StorageNodeDescriptor{
@@ -327,7 +327,7 @@ func TestReplicaSelector(t *testing.T) {
 				cmview := mrmanager.NewMockClusterMetadataView(ctrl)
 				cmview.EXPECT().ClusterMetadata(gomock.Any()).Return(tc.md, nil).AnyTimes()
 
-				s, err := newReplicaSelector(selector, cmview, tc.repfactor)
+				s, err := NewReplicaSelector(selector, cmview, tc.repfactor)
 				require.NoError(t, err)
 				require.Equal(t, selector, s.Name())
 				tc.testf(t, tc, s)