Fail VTBackup early when replication or MySQL is failing (#17356)

Signed-off-by: Florent Poinsard <[email protected]>

go/cmd/vtbackup/cli/vtbackup.go

@@ -19,6 +19,7 @@ package cli
 import (
 	"context"
 	"crypto/rand"
+	"errors"
 	"fmt"
 	"math"
 	"math/big"
@@ -65,6 +66,8 @@ const (
 	phaseNameTakeNewBackup               = "TakeNewBackup"
 	phaseStatusCatchupReplicationStalled = "Stalled"
 	phaseStatusCatchupReplicationStopped = "Stopped"
+
+	timeoutWaitingForReplicationStatus = 60 * time.Second
 )
 
 var (
@@ -335,6 +338,18 @@ func takeBackup(ctx, backgroundCtx context.Context, topoServer *topo.Server, bac
 	if err != nil {
 		return fmt.Errorf("failed to initialize mysql config: %v", err)
 	}
+	ctx, cancelCtx := context.WithCancel(ctx)
+	backgroundCtx, cancelBackgroundCtx := context.WithCancel(backgroundCtx)
+	defer func() {
+		cancelCtx()
+		cancelBackgroundCtx()
+	}()
+	mysqld.OnTerm(func() {
+		log.Warning("Cancelling vtbackup as MySQL has terminated")
+		cancelCtx()
+		cancelBackgroundCtx()
+	})
+
 	initCtx, initCancel := context.WithTimeout(ctx, mysqlTimeout)
 	defer initCancel()
 	initMysqldAt := time.Now()
@@ -520,7 +535,13 @@ func takeBackup(ctx, backgroundCtx context.Context, topoServer *topo.Server, bac
 
 		waitStartTime = time.Now()
 	)
+
+	lastErr := vterrors.NewLastError("replication catch up", timeoutWaitingForReplicationStatus)
 	for {
+		if !lastErr.ShouldRetry() {
+			return fmt.Errorf("timeout waiting for replication status after %.0f seconds", timeoutWaitingForReplicationStatus.Seconds())
+		}
+
 		select {
 		case <-ctx.Done():
 			return fmt.Errorf("error in replication catch up: %v", ctx.Err())
@@ -530,6 +551,7 @@ func takeBackup(ctx, backgroundCtx context.Context, topoServer *topo.Server, bac
 		lastStatus = status
 		status, statusErr = mysqld.ReplicationStatus(ctx)
 		if statusErr != nil {
+			lastErr.Record(statusErr)
 			log.Warningf("Error getting replication status: %v", statusErr)
 			continue
 		}
@@ -548,7 +570,10 @@ func takeBackup(ctx, backgroundCtx context.Context, topoServer *topo.Server, bac
 			}
 		}
 		if !status.Healthy() {
-			log.Warning("Replication has stopped before backup could be taken. Trying to restart replication.")
+			errStr := "Replication has stopped before backup could be taken. Trying to restart replication."
+			log.Warning(errStr)
+			lastErr.Record(errors.New(strings.ToLower(errStr)))
+
 			phaseStatus.Set([]string{phaseNameCatchupReplication, phaseStatusCatchupReplicationStopped}, 1)
 			if err := startReplication(ctx, mysqld, topoServer); err != nil {
 				log.Warningf("Failed to restart replication: %v", err)

go/test/endtoend/backup/vtbackup/backup_only_test.go

@@ -47,6 +47,55 @@ var (
 		) Engine=InnoDB;`
 )
 
+func TestFailingReplication(t *testing.T) {
+	prepareCluster(t)
+
+	// Run the entire backup test
+	firstBackupTest(t, false)
+
+	// Insert one more row, the primary will be ahead of the last backup
+	_, err := primary.VttabletProcess.QueryTablet("insert into vt_insert_test (msg) values ('test_failure')", keyspaceName, true)
+	require.NoError(t, err)
+
+	// Disable replication from the primary by removing the grants to 'vt_repl'.
+	_, err = primary.VttabletProcess.QueryTablet("REVOKE REPLICATION SLAVE ON *.* FROM 'vt_repl'@'%';", keyspaceName, true)
+	require.NoError(t, err)
+	_, err = primary.VttabletProcess.QueryTablet("FLUSH PRIVILEGES;", keyspaceName, true)
+	require.NoError(t, err)
+
+	// Take a backup with vtbackup: the process should fail entirely as it cannot replicate from the primary.
+	_, err = startVtBackup(t, false, false, false)
+	require.Error(t, err)
+
+	// keep in mind how many backups we have right now
+	backups, err := listBackups(shardKsName)
+	require.NoError(t, err)
+
+	// In 30 seconds, grant the replication permission again to 'vt_repl'.
+	// This will mean that vtbackup should fail to replicate for ~30 seconds, until we grant the permission again.
+	go func() {
+		<-time.After(30 * time.Second)
+		_, err = primary.VttabletProcess.QueryTablet("GRANT REPLICATION SLAVE ON *.* TO 'vt_repl'@'%';", keyspaceName, true)
+		require.NoError(t, err)
+		_, err = primary.VttabletProcess.QueryTablet("FLUSH PRIVILEGES;", keyspaceName, true)
+		require.NoError(t, err)
+	}()
+
+	startTime := time.Now()
+	// this will initially be stuck trying to replicate from the primary, and once we re-grant the permission in
+	// the goroutine above, the process will work and complete successfully.
+	_ = vtBackup(t, false, false, false)
+
+	require.GreaterOrEqual(t, time.Since(startTime).Seconds(), float64(30))
+
+	verifyBackupCount(t, shardKsName, len(backups)+1)
+
+	removeBackups(t)
+	verifyBackupCount(t, shardKsName, 0)
+
+	tearDown(t, true)
+}
+
 func TestTabletInitialBackup(t *testing.T) {
 	// Test Initial Backup Flow
 	//    TestTabletInitialBackup will:
@@ -59,6 +108,15 @@ func TestTabletInitialBackup(t *testing.T) {
 	//    - Bring up a second replica, and restore from the second backup
 	//    - list the backups, remove them
 
+	prepareCluster(t)
+
+	// Run the entire backup test
+	firstBackupTest(t, true)
+
+	tearDown(t, true)
+}
+
+func prepareCluster(t *testing.T) {
 	waitForReplicationToCatchup([]cluster.Vttablet{*replica1, *replica2})
 
 	dataPointReader := vtBackup(t, true, false, false)
@@ -84,11 +142,6 @@ func TestTabletInitialBackup(t *testing.T) {
 		"TabletExternallyReparented", primary.Alias)
 	require.NoError(t, err)
 	restore(t, replica1, "replica", "SERVING")
-
-	// Run the entire backup test
-	firstBackupTest(t, "replica")
-
-	tearDown(t, true)
 }
 
 func TestTabletBackupOnly(t *testing.T) {
@@ -107,12 +160,12 @@ func TestTabletBackupOnly(t *testing.T) {
 	replica1.VttabletProcess.ServingStatus = "NOT_SERVING"
 
 	initTablets(t, true, true)
-	firstBackupTest(t, "replica")
+	firstBackupTest(t, true)
 
 	tearDown(t, false)
 }
 
-func firstBackupTest(t *testing.T, tabletType string) {
+func firstBackupTest(t *testing.T, removeBackup bool) {
 	// Test First Backup flow.
 	//
 	//    firstBackupTest will:
@@ -168,11 +221,13 @@ func firstBackupTest(t *testing.T, tabletType string) {
 	// check the new replica has the data
 	cluster.VerifyRowsInTablet(t, replica2, keyspaceName, 2)
 
-	removeBackups(t)
-	verifyBackupCount(t, shardKsName, 0)
+	if removeBackup {
+		removeBackups(t)
+		verifyBackupCount(t, shardKsName, 0)
+	}
 }
 
-func vtBackup(t *testing.T, initialBackup bool, restartBeforeBackup, disableRedoLog bool) *opentsdb.DataPointReader {
+func startVtBackup(t *testing.T, initialBackup bool, restartBeforeBackup, disableRedoLog bool) (*os.File, error) {
 	mysqlSocket, err := os.CreateTemp("", "vtbackup_test_mysql.sock")
 	require.NoError(t, err)
 	defer os.Remove(mysqlSocket.Name())
@@ -207,9 +262,19 @@ func vtBackup(t *testing.T, initialBackup bool, restartBeforeBackup, disableRedo
 
 	log.Infof("starting backup tablet %s", time.Now())
 	err = localCluster.StartVtbackup(newInitDBFile, initialBackup, keyspaceName, shardName, cell, extraArgs...)
-	require.NoError(t, err)
+	if err != nil {
+		return nil, err
+	}
 
 	f, err := os.OpenFile(statsPath, os.O_RDONLY, 0)
+	if err != nil {
+		return nil, err
+	}
+	return f, nil
+}
+
+func vtBackup(t *testing.T, initialBackup bool, restartBeforeBackup, disableRedoLog bool) *opentsdb.DataPointReader {
+	f, err := startVtBackup(t, initialBackup, restartBeforeBackup, disableRedoLog)
 	require.NoError(t, err)
 	return opentsdb.NewDataPointReader(f)
 }