replication: centralize healthcheck for remote targets (#15516)

This PR moves health check from minio-go client to being
managed on the server.

Additionally integrating health check into site replication

cmd/admin-bucket-handlers.go

@@ -249,7 +249,7 @@ func (a adminAPIHandlers) SetRemoteTargetHandler(w http.ResponseWriter, r *http.
 	}
 	if err = globalBucketTargetSys.SetTarget(ctx, bucket, &target, update); err != nil {
 		switch err.(type) {
-		case BucketRemoteConnectionErr:
+		case RemoteTargetConnectionErr:
 			writeErrorResponseJSON(ctx, w, errorCodes.ToAPIErrWithErr(ErrReplicationRemoteConnectionError, err), r.URL)
 		default:
 			writeErrorResponseJSON(ctx, w, toAPIError(ctx, err), r.URL)

cmd/api-errors.go

@@ -888,7 +888,7 @@ var errorCodes = errorCodeMap{
 	},
 	ErrReplicationRemoteConnectionError: {
 		Code:           "XMinioAdminReplicationRemoteConnectionError",
-		Description:    "Remote service connection error - please check remote service credentials and target bucket",
+		Description:    "Remote service connection error",
 		HTTPStatusCode: http.StatusNotFound,
 	},
 	ErrReplicationBandwidthLimitError: {
@@ -2074,7 +2074,7 @@ func toAPIErrorCode(ctx context.Context, err error) (apiErr APIErrorCode) {
 		apiErr = ErrRemoteDestinationNotFoundError
 	case BucketRemoteTargetNotFound:
 		apiErr = ErrRemoteTargetNotFoundError
-	case BucketRemoteConnectionErr:
+	case RemoteTargetConnectionErr:
 		apiErr = ErrReplicationRemoteConnectionError
 	case BucketRemoteAlreadyExists:
 		apiErr = ErrBucketRemoteAlreadyExists

cmd/bucket-replication-handlers.go

@@ -310,7 +310,7 @@ func (api objectAPIHandlers) ResetBucketReplicationStartHandler(w http.ResponseW
 	rinfo.Targets = append(rinfo.Targets, ResyncTarget{Arn: tgtArns[0], ResetID: target.ResetID})
 	if err = globalBucketTargetSys.SetTarget(ctx, bucket, &target, true); err != nil {
 		switch err.(type) {
-		case BucketRemoteConnectionErr:
+		case RemoteTargetConnectionErr:
 			writeErrorResponseJSON(ctx, w, errorCodes.ToAPIErrWithErr(ErrReplicationRemoteConnectionError, err), r.URL)
 		default:
 			writeErrorResponseJSON(ctx, w, toAPIError(ctx, err), r.URL)

cmd/bucket-replication.go

@@ -534,7 +534,7 @@ func replicateDeleteToTarget(ctx context.Context, dobj DeletedObjectReplicationI
 	if dobj.VersionID != "" && rinfo.VersionPurgeStatus == Complete {
 		return
 	}
-	if tgt.IsOffline() {
+	if globalBucketTargetSys.isOffline(tgt.EndpointURL()) {
 		logger.LogIf(ctx, fmt.Errorf("remote target is offline for bucket:%s arn:%s", dobj.Bucket, tgt.ARN))
 		sendEvent(eventArgs{
 			BucketName: dobj.Bucket,
@@ -1039,7 +1039,7 @@ func replicateObjectToTarget(ctx context.Context, ri ReplicateObjectInfo, object
 		rinfo.ReplicationResynced = true
 		return
 	}
-	if tgt.IsOffline() {
+	if globalBucketTargetSys.isOffline(tgt.EndpointURL()) {
 		logger.LogIf(ctx, fmt.Errorf("remote target is offline for bucket:%s arn:%s", bucket, tgt.ARN))
 		sendEvent(eventArgs{
 			EventName:  event.ObjectReplicationNotTracked,
@@ -1659,7 +1659,7 @@ func proxyHeadToRepTarget(ctx context.Context, bucket, object string, rs *HTTPRa
 	}
 	for _, t := range proxyTargets.Targets {
 		tgt = globalBucketTargetSys.GetRemoteTargetClient(ctx, t.Arn)
-		if tgt == nil || tgt.IsOffline() {
+		if tgt == nil || globalBucketTargetSys.isOffline(tgt.EndpointURL()) {
 			continue
 		}
 		// if proxying explicitly disabled on remote target

cmd/bucket-targets.go

@@ -19,6 +19,8 @@ package cmd
 
 import (
 	"context"
+	"fmt"
+	"net/url"
 	"sync"
 	"time"
 
@@ -35,7 +37,9 @@ import (
 )
 
 const (
-	defaultHealthCheckDuration = 30 * time.Second
+	defaultHealthCheckDuration = 5 * time.Second
+	// default interval for reload of all remote target endpoints
+	defaultHealthCheckReloadDuration = 30 * time.Minute
 )
 
 // BucketTargetSys represents bucket targets subsystem
@@ -43,6 +47,113 @@ type BucketTargetSys struct {
 	sync.RWMutex
 	arnRemotesMap map[string]*TargetClient
 	targetsMap    map[string][]madmin.BucketTarget
+	hMutex        sync.RWMutex
+	hc            map[string]epHealth
+	hcClient      *madmin.AnonymousClient
+}
+
+// epHealth struct represents health of a replication target endpoint.
+type epHealth struct {
+	Endpoint string
+	Scheme   string
+	Online   bool
+}
+
+// isOffline returns current liveness result of remote target. Add endpoint to
+// healthcheck map if missing and default to online status
+func (sys *BucketTargetSys) isOffline(ep *url.URL) bool {
+	sys.hMutex.RLock()
+	defer sys.hMutex.RUnlock()
+	if h, ok := sys.hc[ep.Host]; ok {
+		return !h.Online
+	}
+	go sys.initHC(ep)
+	return false
+}
+
+func (sys *BucketTargetSys) initHC(ep *url.URL) {
+	sys.hMutex.Lock()
+	sys.hc[ep.Host] = epHealth{
+		Endpoint: ep.Host,
+		Scheme:   ep.Scheme,
+		Online:   true,
+	}
+	sys.hMutex.Unlock()
+}
+
+// newHCClient initializes an anonymous client for performing health check on the remote endpoints
+func newHCClient() *madmin.AnonymousClient {
+	clnt, e := madmin.NewAnonymousClientNoEndpoint()
+	if e != nil {
+		logger.LogOnceIf(GlobalContext, fmt.Errorf("WARNING: Unable to initialize health check client"), string(replicationSubsystem))
+		return nil
+	}
+	clnt.SetCustomTransport(globalRemoteTargetTransport)
+	return clnt
+}
+
+// heartBeat performs liveness check on remote endpoints.
+func (sys *BucketTargetSys) heartBeat(ctx context.Context) {
+	hcTimer := time.NewTimer(defaultHealthCheckDuration)
+	defer hcTimer.Stop()
+	for {
+		select {
+		case <-hcTimer.C:
+			sys.hMutex.RLock()
+			var eps []madmin.ServerProperties
+			for _, ep := range sys.hc {
+				eps = append(eps, madmin.ServerProperties{Endpoint: ep.Endpoint, Scheme: ep.Scheme})
+			}
+			sys.hMutex.RUnlock()
+
+			if len(eps) > 0 {
+				cctx, cancel := context.WithTimeout(ctx, 30*time.Second)
+				defer cancel()
+				m := map[string]epHealth{}
+				for result := range sys.hcClient.Alive(cctx, madmin.AliveOpts{}, eps...) {
+					var online bool
+					if result.Error == nil {
+						online = result.Online
+					}
+					m[result.Endpoint.Host] = epHealth{
+						Endpoint: result.Endpoint.Host,
+						Scheme:   result.Endpoint.Scheme,
+						Online:   online,
+					}
+				}
+				sys.hMutex.Lock()
+				sys.hc = m
+				sys.hMutex.Unlock()
+			}
+			hcTimer.Reset(defaultHealthCheckDuration)
+		case <-ctx.Done():
+			return
+		}
+	}
+}
+
+// periodically rebuild the healthcheck map from list of targets to clear
+// out stale endpoints
+func (sys *BucketTargetSys) reloadHealthCheckers(ctx context.Context) {
+	m := make(map[string]epHealth)
+	tgts := sys.ListTargets(ctx, "", "")
+	for _, t := range tgts {
+		if _, ok := m[t.Endpoint]; !ok {
+			scheme := "http"
+			if t.Secure {
+				scheme = "https"
+			}
+			m[t.Endpoint] = epHealth{
+				Online:   true,
+				Endpoint: t.Endpoint,
+				Scheme:   scheme,
+			}
+		}
+	}
+	sys.hMutex.Lock()
+	// swap out the map
+	sys.hc = m
+	sys.hMutex.Unlock()
 }
 
 // ListTargets lists bucket targets across tenant or for individual bucket, and returns
@@ -91,9 +202,6 @@ func (sys *BucketTargetSys) Delete(bucket string) {
 		return
 	}
 	for _, t := range tgts {
-		if tgt, ok := sys.arnRemotesMap[t.Arn]; ok && tgt.healthCancelFn != nil {
-			tgt.healthCancelFn()
-		}
 		delete(sys.arnRemotesMap, t.Arn)
 	}
 	delete(sys.targetsMap, bucket)
@@ -116,7 +224,7 @@ func (sys *BucketTargetSys) SetTarget(ctx context.Context, bucket string, tgt *m
 		if minio.ToErrorResponse(err).Code == "NoSuchBucket" {
 			return BucketRemoteTargetNotFound{Bucket: tgt.TargetBucket}
 		}
-		return BucketRemoteConnectionErr{Bucket: tgt.TargetBucket, Err: err}
+		return RemoteTargetConnectionErr{Bucket: tgt.TargetBucket, Err: err}
 	}
 	if tgt.Type == madmin.ReplicationService {
 		if !globalBucketVersioningSys.Enabled(bucket) {
@@ -124,7 +232,7 @@ func (sys *BucketTargetSys) SetTarget(ctx context.Context, bucket string, tgt *m
 		}
 		vcfg, err := clnt.GetBucketVersioning(ctx, tgt.TargetBucket)
 		if err != nil {
-			return BucketRemoteConnectionErr{Bucket: tgt.TargetBucket, Err: err}
+			return RemoteTargetConnectionErr{Bucket: tgt.TargetBucket, Err: err}
 		}
 		if vcfg.Status != string(versioning.Enabled) {
 			return BucketRemoteTargetNotVersioned{Bucket: tgt.TargetBucket}
@@ -152,10 +260,7 @@ func (sys *BucketTargetSys) SetTarget(ctx context.Context, bucket string, tgt *m
 	if !found && !update {
 		newtgts = append(newtgts, *tgt)
 	}
-	// cancel health check for previous target client to avoid leak.
+
-	if prevClnt, ok := sys.arnRemotesMap[tgt.Arn]; ok && prevClnt.healthCancelFn != nil {
-		prevClnt.healthCancelFn()
-	}
 	sys.targetsMap[bucket] = newtgts
 	sys.arnRemotesMap[tgt.Arn] = clnt
 	sys.updateBandwidthLimit(bucket, tgt.BandwidthLimit)
@@ -227,9 +332,6 @@ func (sys *BucketTargetSys) RemoveTarget(ctx context.Context, bucket, arnStr str
 		return BucketRemoteTargetNotFound{Bucket: bucket}
 	}
 	sys.targetsMap[bucket] = targets
-	if tgt, ok := sys.arnRemotesMap[arnStr]; ok && tgt.healthCancelFn != nil {
-		tgt.healthCancelFn()
-	}
 	delete(sys.arnRemotesMap, arnStr)
 	sys.updateBandwidthLimit(bucket, 0)
 	return nil
@@ -258,11 +360,29 @@ func (sys *BucketTargetSys) GetRemoteBucketTargetByArn(ctx context.Context, buck
 }
 
 // NewBucketTargetSys - creates new replication system.
-func NewBucketTargetSys() *BucketTargetSys {
+func NewBucketTargetSys(ctx context.Context) *BucketTargetSys {
-	return &BucketTargetSys{
+	sys := &BucketTargetSys{
 		arnRemotesMap: make(map[string]*TargetClient),
 		targetsMap:    make(map[string][]madmin.BucketTarget),
+		hc:            make(map[string]epHealth),
+		hcClient:      newHCClient(),
 	}
+	// reload healthcheck endpoints map periodically to remove stale endpoints from the map.
+	go func() {
+		rTimer := time.NewTimer(defaultHealthCheckReloadDuration)
+		defer rTimer.Stop()
+		for {
+			select {
+			case <-rTimer.C:
+				sys.reloadHealthCheckers(ctx)
+				rTimer.Reset(defaultHealthCheckReloadDuration)
+			case <-ctx.Done():
+				return
+			}
+		}
+	}()
+	go sys.heartBeat(ctx)
+	return sys
 }
 
 // UpdateAllTargets updates target to reflect metadata updates
@@ -276,9 +396,6 @@ func (sys *BucketTargetSys) UpdateAllTargets(bucket string, tgts *madmin.BucketT
 	// Remove existingtarget and arn association
 	if tgts, ok := sys.targetsMap[bucket]; ok {
 		for _, t := range tgts {
-			if tgt, ok := sys.arnRemotesMap[t.Arn]; ok && tgt.healthCancelFn != nil {
-				tgt.healthCancelFn()
-			}
 			delete(sys.arnRemotesMap, t.Arn)
 		}
 		delete(sys.targetsMap, bucket)
@@ -345,10 +462,6 @@ func (sys *BucketTargetSys) getRemoteTargetClient(tcfg *madmin.BucketTarget) (*T
 	if tcfg.HealthCheckDuration >= 1 { // require minimum health check duration of 1 sec.
 		hcDuration = tcfg.HealthCheckDuration
 	}
-	cancelFn, err := api.HealthCheck(hcDuration)
-	if err != nil {
-		return nil, err
-	}
 	tc := &TargetClient{
 		Client:              api,
 		healthCheckDuration: hcDuration,
@@ -356,9 +469,10 @@ func (sys *BucketTargetSys) getRemoteTargetClient(tcfg *madmin.BucketTarget) (*T
 		Bucket:              tcfg.TargetBucket,
 		StorageClass:        tcfg.StorageClass,
 		disableProxy:        tcfg.DisableProxy,
-		healthCancelFn:      cancelFn,
 		ARN:                 tcfg.Arn,
 		ResetID:             tcfg.ResetID,
+		Endpoint:            tcfg.Endpoint,
+		Secure:              tcfg.Secure,
 	}
 	return tc, nil
 }
@@ -432,7 +546,8 @@ type TargetClient struct {
 	replicateSync       bool
 	StorageClass        string // storage class on remote
 	disableProxy        bool
-	healthCancelFn      context.CancelFunc // cancellation function for client healthcheck
 	ARN                 string // ARN to uniquely identify remote target
 	ResetID             string
+	Endpoint            string
+	Secure              bool
 }

cmd/object-api-errors.go

@@ -422,11 +422,18 @@ func (e BucketRemoteTargetNotFound) Error() string {
 	return "Remote target not found: " + e.Bucket
 }
 
-// BucketRemoteConnectionErr remote target connection failure.
+// RemoteTargetConnectionErr remote target connection failure.
-type BucketRemoteConnectionErr GenericError
+type RemoteTargetConnectionErr struct {
+	Err      error
+	Bucket   string
+	Endpoint string
+}
 
-func (e BucketRemoteConnectionErr) Error() string {
+func (e RemoteTargetConnectionErr) Error() string {
-	return fmt.Sprintf("Remote service endpoint or target bucket not available: %s \n\t%s", e.Bucket, e.Err.Error())
+	if e.Bucket != "" {
+		return fmt.Sprintf("Remote service endpoint offline or target bucket/remote service credentials invalid: %s \n\t%s", e.Bucket, e.Err.Error())
+	}
+	return fmt.Sprintf("Remote service endpoint %s not available\n\t%s", e.Endpoint, e.Err.Error())
 }
 
 // BucketRemoteAlreadyExists remote already exists for this target type.

cmd/server-main.go

@@ -290,7 +290,7 @@ func initAllSubsystems() {
 	}
 
 	// Create new bucket replication subsytem
-	globalBucketTargetSys = NewBucketTargetSys()
+	globalBucketTargetSys = NewBucketTargetSys(GlobalContext)
 
 	// Create new ILM tier configuration subsystem
 	globalTierConfigMgr = NewTierConfigMgr()

cmd/site-replication.go

@@ -2217,6 +2217,9 @@ func getAdminClient(endpoint, accessKey, secretKey string) (*madmin.AdminClient,
 	if err != nil {
 		return nil, err
 	}
+	if globalBucketTargetSys.isOffline(epURL) {
+		return nil, RemoteTargetConnectionErr{Endpoint: epURL.String(), Err: fmt.Errorf("remote target is offline for endpoint %s", epURL.String())}
+	}
 	client, err := madmin.New(epURL.Host, accessKey, secretKey, epURL.Scheme == "https")
 	if err != nil {
 		return nil, err
@@ -2230,6 +2233,10 @@ func getS3Client(pc madmin.PeerSite) (*minioClient.Client, error) {
 	if err != nil {
 		return nil, err
 	}
+	if globalBucketTargetSys.isOffline(ep) {
+		return nil, RemoteTargetConnectionErr{Endpoint: ep.String(), Err: fmt.Errorf("remote target is offline for endpoint %s", ep.String())}
+	}
+
 	return minioClient.New(ep.Host, &minioClient.Options{
 		Creds:     credentials.NewStaticV4(pc.AccessKey, pc.SecretKey, ""),
 		Secure:    ep.Scheme == "https",

go.mod

@@ -48,7 +48,7 @@ require (
 	github.com/minio/dperf v0.4.2
 	github.com/minio/highwayhash v1.0.2
 	github.com/minio/kes v0.20.0
-	github.com/minio/madmin-go v1.4.17
+	github.com/minio/madmin-go v1.4.20
 	github.com/minio/minio-go/v7 v7.0.34
 	github.com/minio/pkg v1.3.0
 	github.com/minio/selfupdate v0.5.0

go.sum

@@ -622,8 +622,8 @@ github.com/minio/highwayhash v1.0.2/go.mod h1:BQskDq+xkJ12lmlUUi7U0M5Swg3EWR+dLT
 github.com/minio/kes v0.20.0 h1:1tyC51Rr8zTregTESuT/QN/iebNMX7B9t7d3xLNMEpE=
 github.com/minio/kes v0.20.0/go.mod h1:3FW1BQkMGQW78yhy+69tUq5bdcf5rnXJizyeKB9a/tc=
 github.com/minio/madmin-go v1.3.5/go.mod h1:vGKGboQgGIWx4DuDUaXixjlIEZOCIp6ivJkQoiVaACc=
-github.com/minio/madmin-go v1.4.17 h1:o8b42lrJW9qyIthIa+24IzygZjmPm04iSUSBITcvzYU=
+github.com/minio/madmin-go v1.4.20 h1:OpPxc8uIaevJMpBGSZ2TXJvFGvPSDn0IT3VJPh7w90M=
-github.com/minio/madmin-go v1.4.17/go.mod h1:ez87VmMtsxP7DRxjKJKD4RDNW+nhO2QF9KSzwxBDQ98=
+github.com/minio/madmin-go v1.4.20/go.mod h1:ez87VmMtsxP7DRxjKJKD4RDNW+nhO2QF9KSzwxBDQ98=
 github.com/minio/mc v0.0.0-20220805080128-351d021b924b h1:ikMXncKqNE/0acH6us6yy3v+gJBP7nGv/3Rc9F7vRio=
 github.com/minio/mc v0.0.0-20220805080128-351d021b924b/go.mod h1:YUXIqqgGfFknByv0eeJSMBQl/WGuEN0XkpW68/ghBm0=
 github.com/minio/md5-simd v1.1.0/go.mod h1:XpBqgZULrMYD3R+M28PcmP0CkI7PEMzB3U77ZrKZ0Gw=