sync: add --concurrency and --retry-timeout flags

cmd/bundle/sync.go

@@ -17,11 +17,13 @@ import (
 )
 
 type syncFlags struct {
-	interval time.Duration
-	full     bool
-	watch    bool
-	output   flags.Output
-	dryRun   bool
+	interval     time.Duration
+	full         bool
+	watch        bool
+	output       flags.Output
+	dryRun       bool
+	concurrency  int
+	retryTimeout time.Duration
 }
 
 func (f *syncFlags) syncOptionsFromBundle(cmd *cobra.Command, b *bundle.Bundle) (*sync.SyncOptions, error) {
@@ -48,6 +50,8 @@ func (f *syncFlags) syncOptionsFromBundle(cmd *cobra.Command, b *bundle.Bundle)
 	opts.Full = f.full
 	opts.PollInterval = f.interval
 	opts.DryRun = f.dryRun
+	opts.Concurrency = f.concurrency
+	opts.RetryTimeout = f.retryTimeout
 	return opts, nil
 }
 
@@ -74,8 +78,17 @@ Use 'databricks bundle deploy' for full resource deployment.`,
 	cmd.Flags().BoolVar(&f.watch, "watch", false, "watch local file system for changes")
 	cmd.Flags().Var(&f.output, "output", "type of the output format")
 	cmd.Flags().BoolVar(&f.dryRun, "dry-run", false, "simulate sync execution without making actual changes")
+	cmd.Flags().IntVar(&f.concurrency, "concurrency", 5, "maximum number of concurrent in-flight requests during sync")
+	cmd.Flags().DurationVar(&f.retryTimeout, "retry-timeout", sync.DefaultRetryTimeout, "per-call deadline for retrying transient gateway errors (HTTP 502/503/504)")
 
 	cmd.RunE = func(cmd *cobra.Command, args []string) error {
+		if f.concurrency < 1 {
+			return fmt.Errorf("--concurrency must be a positive integer, got %d", f.concurrency)
+		}
+		if f.retryTimeout < 0 {
+			return fmt.Errorf("--retry-timeout must be non-negative, got %s", f.retryTimeout)
+		}
+
 		b, err := utils.ProcessBundle(cmd, utils.ProcessOptions{})
 		if err != nil {
 			return err

cmd/sync/sync.go

@@ -26,15 +26,17 @@ import (
 
 type syncFlags struct {
 	// project files polling interval
-	interval    time.Duration
-	full        bool
-	watch       bool
-	output      flags.Output
-	exclude     []string
-	include     []string
-	dryRun      bool
-	excludeFrom string
-	includeFrom string
+	interval     time.Duration
+	full         bool
+	watch        bool
+	output       flags.Output
+	exclude      []string
+	include      []string
+	dryRun       bool
+	excludeFrom  string
+	includeFrom  string
+	concurrency  int
+	retryTimeout time.Duration
 }
 
 func readPatternsFile(filePath string) ([]string, error) {
@@ -89,6 +91,8 @@ func (f *syncFlags) syncOptionsFromBundle(cmd *cobra.Command, args []string, b *
 	opts.Include = append(opts.Include, f.include...)
 	opts.Include = append(opts.Include, includePatterns...)
 	opts.DryRun = f.dryRun
+	opts.Concurrency = f.concurrency
+	opts.RetryTimeout = f.retryTimeout
 	return opts, nil
 }
 
@@ -163,6 +167,8 @@ func (f *syncFlags) syncOptionsFromArgs(cmd *cobra.Command, args []string) (*syn
 
 		OutputHandler: outputHandler,
 		DryRun:        f.dryRun,
+		Concurrency:   f.concurrency,
+		RetryTimeout:  f.retryTimeout,
 	}
 	return &opts, nil
 }
@@ -187,6 +193,8 @@ func New() *cobra.Command {
 	cmd.Flags().StringVar(&f.excludeFrom, "exclude-from", "", "file containing patterns to exclude from sync (one pattern per line)")
 	cmd.Flags().StringVar(&f.includeFrom, "include-from", "", "file containing patterns to include to sync (one pattern per line)")
 	cmd.Flags().BoolVar(&f.dryRun, "dry-run", false, "simulate sync execution without making actual changes")
+	cmd.Flags().IntVar(&f.concurrency, "concurrency", 5, "maximum number of concurrent in-flight requests during sync")
+	cmd.Flags().DurationVar(&f.retryTimeout, "retry-timeout", sync.DefaultRetryTimeout, "per-call deadline for retrying transient gateway errors (HTTP 502/503/504)")
 
 	// Wrapper for [root.MustWorkspaceClient] that disables loading authentication configuration from a bundle.
 	mustWorkspaceClient := func(cmd *cobra.Command, args []string) error {
@@ -196,6 +204,13 @@ func New() *cobra.Command {
 
 	cmd.PreRunE = mustWorkspaceClient
 	cmd.RunE = func(cmd *cobra.Command, args []string) error {
+		if f.concurrency < 1 {
+			return fmt.Errorf("--concurrency must be a positive integer, got %d", f.concurrency)
+		}
+		if f.retryTimeout < 0 {
+			return fmt.Errorf("--retry-timeout must be non-negative, got %s", f.retryTimeout)
+		}
+
 		var opts *sync.SyncOptions
 		var err error
 

libs/sync/retry.go

@@ -0,0 +1,50 @@
+package sync
+
+import (
+	"context"
+	"errors"
+	"net/http"
+	"time"
+
+	"github.com/databricks/cli/libs/log"
+	"github.com/databricks/databricks-sdk-go/apierr"
+	"github.com/databricks/databricks-sdk-go/retries"
+)
+
+// DefaultRetryTimeout bounds how long the sync layer keeps retrying transient
+// gateway errors per filer call. The SDK only retries 429 and 504
+// (httpclient/errors.go DefaultErrorRetriable); 502 and 503 land here.
+const DefaultRetryTimeout = 30 * time.Second
+
+func isTransientGatewayError(err error) bool {
+	var aerr *apierr.APIError
+	if !errors.As(err, &aerr) {
+		return false
+	}
+	switch aerr.StatusCode {
+	case http.StatusBadGateway, http.StatusServiceUnavailable, http.StatusGatewayTimeout:
+		return true
+	}
+	return false
+}
+
+// retryOnTransient runs fn, retrying transient gateway errors
+// (HTTP 502/503/504) until timeout elapses. Backoff and jitter are provided
+// by retries.Poll.
+func retryOnTransient(ctx context.Context, timeout time.Duration, label string, fn func() error) error {
+	if timeout <= 0 {
+		return fn()
+	}
+	_, err := retries.Poll(ctx, timeout, func() (*struct{}, *retries.Err) {
+		err := fn()
+		if err == nil {
+			return nil, nil
+		}
+		if !isTransientGatewayError(err) {
+			return nil, retries.Halt(err)
+		}
+		log.Warnf(ctx, "sync %s: retrying after transient error: %s", label, err)
+		return nil, retries.Continue(err)
+	})
+	return err
+}

libs/sync/retry_test.go

@@ -0,0 +1,86 @@
+package sync
+
+import (
+	"context"
+	"errors"
+	"net/http"
+	"sync/atomic"
+	"testing"
+	"time"
+
+	"github.com/databricks/databricks-sdk-go/apierr"
+	"github.com/stretchr/testify/require"
+)
+
+func apiErr(status int) error {
+	return &apierr.APIError{StatusCode: status, Message: http.StatusText(status)}
+}
+
+func TestIsTransientGatewayError(t *testing.T) {
+	cases := map[error]bool{
+		nil:                                    false,
+		apiErr(http.StatusBadGateway):          true,
+		apiErr(http.StatusServiceUnavailable):  true,
+		apiErr(http.StatusGatewayTimeout):      true,
+		apiErr(http.StatusInternalServerError): false,
+		apiErr(http.StatusTooManyRequests):     false,
+		apiErr(http.StatusNotFound):            false,
+		errors.New("not an api error"):         false,
+	}
+	for err, want := range cases {
+		require.Equal(t, want, isTransientGatewayError(err), "%v", err)
+	}
+}
+
+func TestRetryOnTransient(t *testing.T) {
+	t.Run("succeeds after retries", func(t *testing.T) {
+		var calls atomic.Int32
+		err := retryOnTransient(t.Context(), 30*time.Second, "test", func() error {
+			if calls.Add(1) < 3 {
+				return apiErr(http.StatusBadGateway)
+			}
+			return nil
+		})
+		require.NoError(t, err)
+		require.Equal(t, int32(3), calls.Load())
+	})
+
+	t.Run("does not retry non-transient", func(t *testing.T) {
+		var calls atomic.Int32
+		err := retryOnTransient(t.Context(), 30*time.Second, "test", func() error {
+			calls.Add(1)
+			return apiErr(http.StatusNotFound)
+		})
+		require.Error(t, err)
+		require.Equal(t, int32(1), calls.Load())
+	})
+
+	t.Run("zero timeout disables retries", func(t *testing.T) {
+		var calls atomic.Int32
+		err := retryOnTransient(t.Context(), 0, "test", func() error {
+			calls.Add(1)
+			return apiErr(http.StatusBadGateway)
+		})
+		require.Error(t, err)
+		require.Equal(t, int32(1), calls.Load())
+	})
+
+	t.Run("times out on persistent transient error", func(t *testing.T) {
+		var calls atomic.Int32
+		err := retryOnTransient(t.Context(), 100*time.Millisecond, "test", func() error {
+			calls.Add(1)
+			return apiErr(http.StatusBadGateway)
+		})
+		require.Error(t, err)
+		require.GreaterOrEqual(t, calls.Load(), int32(1))
+	})
+
+	t.Run("honors context cancellation", func(t *testing.T) {
+		ctx, cancel := context.WithCancel(t.Context())
+		cancel()
+		err := retryOnTransient(ctx, 30*time.Second, "test", func() error {
+			return apiErr(http.StatusBadGateway)
+		})
+		require.Error(t, err)
+	})
+}

libs/sync/sync.go

@@ -43,6 +43,15 @@ type SyncOptions struct {
 	OutputHandler OutputHandler
 
 	DryRun bool
+
+	// Concurrency is the maximum number of in-flight filer requests during sync.
+	// Defaults to MaxRequestsInFlight when zero.
+	Concurrency int
+
+	// RetryTimeout bounds how long each filer call may keep retrying transient
+	// gateway errors (HTTP 502/503/504). Defaults to DefaultRetryTimeout when
+	// zero; a negative value disables sync-layer retries.
+	RetryTimeout time.Duration
 }
 
 type Sync struct {
@@ -96,6 +105,13 @@ func New(ctx context.Context, opts SyncOptions) (*Sync, error) {
 		return nil, errors.New("failed to resolve host for snapshot")
 	}
 
+	if opts.Concurrency == 0 {
+		opts.Concurrency = MaxRequestsInFlight
+	}
+	if opts.RetryTimeout == 0 {
+		opts.RetryTimeout = DefaultRetryTimeout
+	}
+
 	// For full sync, we start with an empty snapshot.
 	// For incremental sync, we try to load an existing snapshot to start from.
 	var snapshot *Snapshot
@@ -119,7 +135,7 @@ func New(ctx context.Context, opts SyncOptions) (*Sync, error) {
 	var notifier EventNotifier
 	outputWaitGroup := &stdsync.WaitGroup{}
 	if opts.OutputHandler != nil {
-		ch := make(chan Event, MaxRequestsInFlight)
+		ch := make(chan Event, opts.Concurrency)
 		notifier = &ChannelNotifier{ch}
 		outputWaitGroup.Go(func() {
 			opts.OutputHandler(ctx, ch)