exporter: use local filesystem generation for tar exporter

This connects the tar exporter and the local exporter to the same fileystem generation, similar to the approach followed by the shared ImageWriter used in both the containerimage and oci packages. This allows the tar exporter to use the same attestations generation logic, so attestations are now supported for the tar exporter. Signed-off-by: Justin Chadwell <[email protected]>
moby · Nov 22, 2022 · 78f5484 · 78f5484
1 parent 3f125a6
commit 78f5484
Showing 1 changed file with 30 additions and 72 deletions.
diff --git a/exporter/tar/export.go b/exporter/tar/export.go
@@ -8,21 +8,23 @@ import (
 	"strings"
 	"time"
 
-	"github.com/docker/docker/pkg/idtools"
 	"github.com/moby/buildkit/cache"
 	"github.com/moby/buildkit/exporter"
 	"github.com/moby/buildkit/exporter/containerimage/exptypes"
+	"github.com/moby/buildkit/exporter/local"
 	"github.com/moby/buildkit/exporter/util/epoch"
 	"github.com/moby/buildkit/session"
 	"github.com/moby/buildkit/session/filesync"
-	"github.com/moby/buildkit/snapshot"
+	"github.com/moby/buildkit/solver/result"
 	"github.com/moby/buildkit/util/progress"
 	"github.com/pkg/errors"
 	"github.com/tonistiigi/fsutil"
 	fstypes "github.com/tonistiigi/fsutil/types"
 )
 
 const (
+	attestationPrefixKey = "attestation-prefix"
+
 	// preferNondistLayersKey is an exporter option which can be used to mark a layer as non-distributable if the layer reference was
 	// already found to use a non-distributable media type.
 	// When this option is not set, the exporter will change the media type of the layer to a distributable one.
@@ -50,24 +52,28 @@ func (e *localExporter) Resolve(ctx context.Context, opt map[string]string) (exp
 	if err != nil {
 		return nil, err
 	}
-	li.epoch = tm
+	li.opts.Epoch = tm
 
-	v, ok := opt[preferNondistLayersKey]
-	if ok {
-		b, err := strconv.ParseBool(v)
-		if err != nil {
-			return nil, errors.Wrapf(err, "non-bool value for %s: %s", preferNondistLayersKey, v)
+	for k, v := range opt {
+		switch k {
+		case preferNondistLayersKey:
+			b, err := strconv.ParseBool(v)
+			if err != nil {
+				return nil, errors.Wrapf(err, "non-bool value for %s: %s", preferNondistLayersKey, v)
+			}
+			li.preferNonDist = b
+		case attestationPrefixKey:
+			li.opts.AttestationPrefix = v
 		}
-		li.preferNonDist = b
 	}
 
 	return li, nil
 }
 
 type localExporterInstance struct {
 	*localExporter
+	opts          local.CreateFSOpts
 	preferNonDist bool
-	epoch         *time.Time
 }
 
 func (e *localExporterInstance) Name() string {
@@ -79,89 +85,41 @@ func (e *localExporterInstance) Config() *exporter.Config {
 }
 
 func (e *localExporterInstance) Export(ctx context.Context, inp *exporter.Source, sessionID string) (map[string]string, error) {
-	var defers []func()
+	var defers []func() error
 
 	defer func() {
 		for i := len(defers) - 1; i >= 0; i-- {
 			defers[i]()
 		}
 	}()
 
-	if e.epoch == nil {
+	if e.opts.Epoch == nil {
 		if tm, ok, err := epoch.ParseSource(inp); err != nil {
 			return nil, err
 		} else if ok {
-			e.epoch = tm
+			e.opts.Epoch = tm
 		}
 	}
 
-	getDir := func(ctx context.Context, k string, ref cache.ImmutableRef) (*fsutil.Dir, error) {
-		var src string
-		var err error
-		var idmap *idtools.IdentityMapping
-		if ref == nil {
-			src, err = os.MkdirTemp("", "buildkit")
-			if err != nil {
-				return nil, err
-			}
-			defers = append(defers, func() { os.RemoveAll(src) })
-		} else {
-			mount, err := ref.Mount(ctx, true, session.NewGroup(sessionID))
-			if err != nil {
-				return nil, err
-			}
-
-			lm := snapshot.LocalMounter(mount)
-
-			src, err = lm.Mount()
-			if err != nil {
-				return nil, err
-			}
-
-			idmap = mount.IdentityMapping()
-
-			defers = append(defers, func() { lm.Unmount() })
-		}
-
-		walkOpt := &fsutil.WalkOpt{}
-		var idMapFunc func(p string, st *fstypes.Stat) fsutil.MapResult
-
-		if idmap != nil {
-			idMapFunc = func(p string, st *fstypes.Stat) fsutil.MapResult {
-				uid, gid, err := idmap.ToContainer(idtools.Identity{
-					UID: int(st.Uid),
-					GID: int(st.Gid),
-				})
-				if err != nil {
-					return fsutil.MapResultExclude
-				}
-				st.Uid = uint32(uid)
-				st.Gid = uint32(gid)
-				return fsutil.MapResultKeep
-			}
+	getDir := func(ctx context.Context, k string, ref cache.ImmutableRef, attestations []result.Attestation) (*fsutil.Dir, error) {
+		outputFS, cleanup, err := local.CreateFS(ctx, sessionID, k, ref, inp.Refs, attestations, e.opts)
+		if err != nil {
+			return nil, err
 		}
-
-		walkOpt.Map = func(p string, st *fstypes.Stat) fsutil.MapResult {
-			res := fsutil.MapResultKeep
-			if idMapFunc != nil {
-				res = idMapFunc(p, st)
-			}
-			if e.epoch != nil {
-				st.ModTime = e.epoch.UnixNano()
-			}
-			return res
+		if cleanup != nil {
+			defers = append(defers, cleanup)
 		}
 
 		st := fstypes.Stat{
 			Mode: uint32(os.ModeDir | 0755),
 			Path: strings.Replace(k, "/", "_", -1),
 		}
-		if e.epoch != nil {
-			st.ModTime = e.epoch.UnixNano()
+		if e.opts.Epoch != nil {
+			st.ModTime = e.opts.Epoch.UnixNano()
 		}
 
 		return &fsutil.Dir{
-			FS:   fsutil.NewFS(src, walkOpt),
+			FS:   outputFS,
 			Stat: st,
 		}, nil
 	}
@@ -187,7 +145,7 @@ func (e *localExporterInstance) Export(ctx context.Context, inp *exporter.Source
 			if !ok {
 				return nil, errors.Errorf("failed to find ref for ID %s", p.ID)
 			}
-			d, err := getDir(ctx, p.ID, r)
+			d, err := getDir(ctx, p.ID, r, inp.Attestations[p.ID])
 			if err != nil {
 				return nil, err
 			}
@@ -199,7 +157,7 @@ func (e *localExporterInstance) Export(ctx context.Context, inp *exporter.Source
 			return nil, err
 		}
 	} else {
-		d, err := getDir(ctx, "", inp.Ref)
+		d, err := getDir(ctx, "", inp.Ref, nil)
 		if err != nil {
 			return nil, err
 		}