Add support for disambiguating multiple responses for cache exporters

by adding IDs similar to output exporters.

Signed-off-by: a-palchikov <deemok@gmail.com>

Author: a-palchikov

api/services/control/control.pb.go

@@ -102,6 +102,9 @@ message CacheOptionsEntry {
 	// Attrs are like mode=(min,max), ref=example.com:5000/foo/bar .
 	// See cache importer/exporter implementations' documentation.
 	map<string, string> Attrs = 2;
+	// ID identifies this exporter.
+	// ID should be treated by the exporter as opaque.
+	string ID = 3;
 }
 
 message SolveResponse {

api/services/control/control.proto

@@ -47,50 +47,63 @@ type SolveOpt struct {
 	CacheImports        []CacheOptionsEntry
 	Session             []session.Attachable
 	AllowedEntitlements []string
-	// When the session is custom-initialized, ParseExporterOpts need to be used to correctly
-	// set up the session for export.
+	// When the session is custom-initialized, Init can be used to
+	// set up the session for export automatically.
 	SharedSession         *session.Session // TODO: refactor to better session syncing
 	SessionPreInitialized bool             // TODO: refactor to better session syncing
 	Internal              bool
 	SourcePolicy          *spb.Policy
 	Ref                   string
 
-	// internal exporter state
+	// internal solver state
 	s solverState
 }
 
 type solverState struct {
-	// storesToUpdate maps exporter ID -> oci store
-	storesToUpdate map[string]ociStore
-	cacheOpt       *cacheOptions
+	exporterOpt *exporterOptions
+	cacheOpt    *cacheOptions
 	// Only one of runGateway or def can be set.
 	// runGateway optionally defines the gateway callback
 	runGateway runGatewayCB
 	// def optionally defines the LLB definition for the client
 	def *llb.Definition
 }
 
+type exporterOptions struct {
+	// storesToUpdate maps exporter ID -> oci store
+	storesToUpdate map[string]ociStore
+}
+
 type cacheOptions struct {
 	options        controlapi.CacheOptions
 	contentStores  map[string]content.Store // key: ID of content store ("local:" + csDir)
-	storesToUpdate map[string]string        // key: path to content store, value: tag
+	storesToUpdate map[string]ociStore      // key: exporter ID
 	frontendAttrs  map[string]string
 }
 
 type ociStore struct {
 	path string
+	tag  string
 }
 
 type ExportEntry struct {
 	Type      string
 	Attrs     map[string]string
 	Output    filesync.FileOutputFunc // for ExporterOCI and ExporterDocker
 	OutputDir string                  // for ExporterLocal
+
+	// id identifies the exporter in the configuration.
+	// Will be assigned automatically and should not be set by the user.
+	id string
 }
 
 type CacheOptionsEntry struct {
 	Type  string
 	Attrs map[string]string
+
+	// id identifies the exporter in the configuration.
+	// Will be assigned automatically and should not be set by the user.
+	id string
 }
 
 // Solve calls Solve on the controller.
@@ -115,9 +128,32 @@ func (c *Client) Solve(ctx context.Context, def *llb.Definition, opt SolveOpt, s
 
 type runGatewayCB func(ref string, s *session.Session, opts map[string]string) error
 
-// ParseExporterOpts configures the specified session with the underlying exporter configuration.
+// Init initializes the SolveOpt.
+// It parses and initializes the cache exports/imports and output exporters.
+func (opt *SolveOpt) Init(ctx context.Context, s *session.Session) error {
+	opt.initExporterIDs()
+	if err := opt.parseCacheOptions(ctx); err != nil {
+		return err
+	}
+	return opt.parseExporterOptions(s)
+}
+
+func (opt *SolveOpt) initExporterIDs() {
+	for i := range opt.Exports {
+		opt.Exports[i].id = strconv.Itoa(i)
+	}
+	for i := range opt.CacheExports {
+		opt.CacheExports[i].id = strconv.Itoa(i)
+	}
+}
+
+// parseExporterOptions configures the specified session with the underlying exporter configuration.
 // It needs to be invoked *after* ParseCacheOpts
-func ParseExporterOpts(opt *SolveOpt, s *session.Session) error {
+func (opt *SolveOpt) parseExporterOptions(s *session.Session) error {
+	if opt.s.exporterOpt != nil {
+		return nil
+	}
+
 	mounts, err := prepareMounts(opt)
 	if err != nil {
 		return err
@@ -145,8 +181,9 @@ func ParseExporterOpts(opt *SolveOpt, s *session.Session) error {
 		contentStores[key2] = store
 	}
 
+	opt.s.exporterOpt = &exporterOptions{}
 	var syncTargets []filesync.FSSyncTarget
-	for exID, ex := range opt.Exports {
+	for _, ex := range opt.Exports {
 		var supportFile bool
 		var supportDir bool
 		switch ex.Type {
@@ -171,7 +208,7 @@ func ParseExporterOpts(opt *SolveOpt, s *session.Session) error {
 			if ex.Output == nil {
 				return errors.Errorf("output file writer is required for %s exporter", ex.Type)
 			}
-			syncTargets = append(syncTargets, filesync.WithFSSync(exID, ex.Output))
+			syncTargets = append(syncTargets, filesync.WithFSSync(ex.id, ex.Output))
 		}
 		if supportDir {
 			if ex.OutputDir == "" {
@@ -187,12 +224,12 @@ func ParseExporterOpts(opt *SolveOpt, s *session.Session) error {
 					return err
 				}
 				contentStores["export"] = cs
-				if opt.s.storesToUpdate == nil {
-					opt.s.storesToUpdate = make(map[string]ociStore)
+				if opt.s.exporterOpt.storesToUpdate == nil {
+					opt.s.exporterOpt.storesToUpdate = make(map[string]ociStore)
 				}
-				opt.s.storesToUpdate[strconv.Itoa(exID)] = ociStore{path: ex.OutputDir}
+				opt.s.exporterOpt.storesToUpdate[ex.id] = ociStore{path: ex.OutputDir}
 			default:
-				syncTargets = append(syncTargets, filesync.WithFSSyncDir(exID, ex.OutputDir))
+				syncTargets = append(syncTargets, filesync.WithFSSyncDir(ex.id, ex.OutputDir))
 			}
 		}
 	}
@@ -236,13 +273,15 @@ func (c *Client) solve(ctx context.Context, opt SolveOpt, statusChan chan *Solve
 		}
 	}
 
-	err := ParseCacheOptions(ctx, &opt)
+	opt.initExporterIDs()
+
+	err := opt.parseCacheOptions(ctx)
 	if err != nil {
 		return nil, err
 	}
 
 	if !opt.SessionPreInitialized {
-		if err := ParseExporterOpts(&opt, s); err != nil {
+		if err := opt.parseExporterOptions(s); err != nil {
 			return nil, err
 		}
 
@@ -299,8 +338,7 @@ func (c *Client) solve(ctx context.Context, opt SolveOpt, statusChan chan *Solve
 			exports = append(exports, &controlapi.Exporter{
 				Type:  exp.Type,
 				Attrs: exp.Attrs,
-				// Keep this in sync with SetupExporters id assignment
-				ID: strconv.Itoa(i),
+				ID:    exp.id,
 			})
 		}
 
@@ -330,6 +368,7 @@ func (c *Client) solve(ctx context.Context, opt SolveOpt, statusChan chan *Solve
 		for _, resp := range resp.ExporterResponses {
 			res.ExporterResponses = append(res.ExporterResponses, ExporterResponse{
 				ID:   resp.Metadata.ID,
+				Type: resp.Metadata.Type,
 				Data: resp.Data,
 			})
 		}
@@ -389,26 +428,27 @@ func (c *Client) solve(ctx context.Context, opt SolveOpt, statusChan chan *Solve
 	if err := eg.Wait(); err != nil {
 		return nil, err
 	}
-	// Update index.json of exported cache content store
-	// FIXME(AkihiroSuda): dedupe const definition of cache/remotecache.ExporterResponseManifestDesc = "cache.manifest"
-	if manifestDescJSON := res.ExporterResponse["cache.manifest"]; manifestDescJSON != "" {
-		var manifestDesc ocispecs.Descriptor
-		if err = json.Unmarshal([]byte(manifestDescJSON), &manifestDesc); err != nil {
+
+	for id, store := range opt.s.cacheOpt.storesToUpdate {
+		// Update index.json of exported cache content store
+		manifestDesc, err := getCacheManifestDescriptor(id, res)
+		if err != nil {
 			return nil, err
 		}
-		for storePath, tag := range opt.s.cacheOpt.storesToUpdate {
-			idx := ociindex.NewStoreIndex(storePath)
-			if err := idx.Put(manifestDesc, ociindex.Tag(tag)); err != nil {
-				return nil, err
-			}
+		if manifestDesc == nil {
+			continue
+		}
+		idx := ociindex.NewStoreIndex(store.path)
+		if err := idx.Put(*manifestDesc, ociindex.Tag(store.tag)); err != nil {
+			return nil, err
 		}
 	}
 
-	if len(opt.s.storesToUpdate) == 0 {
+	if len(opt.s.exporterOpt.storesToUpdate) == 0 {
 		return res, nil
 	}
-	for id, store := range opt.s.storesToUpdate {
-		manifestDesc, err := getManifestDescriptor(id, res)
+	for id, store := range opt.s.exporterOpt.storesToUpdate {
+		manifestDesc, err := getImageManifestDescriptor(id, res)
 		if err != nil {
 			return nil, err
 		}
@@ -433,25 +473,43 @@ func (c *Client) solve(ctx context.Context, opt SolveOpt, statusChan chan *Solve
 	return res, nil
 }
 
-func getManifestDescriptor(exporterID string, resp *SolveResponse) (*ocispecs.Descriptor, error) {
+func getCacheManifestDescriptor(exporterID string, resp *SolveResponse) (*ocispecs.Descriptor, error) {
+	const exporterResponseManifestDesc = "cache.manifest"
+	if resp := resp.cacheExporter(exporterID); resp != nil {
+		// FIXME(AkihiroSuda): dedupe const definition of cache/remotecache.ExporterResponseManifestDesc = "cache.manifest"
+		if manifestDescDt := resp.Data[exporterResponseManifestDesc]; manifestDescDt != "" {
+			return unmarshalManifestDescriptor(manifestDescDt)
+		}
+	}
+	if manifestDescDt := resp.ExporterResponse[exporterResponseManifestDesc]; manifestDescDt != "" {
+		return unmarshalManifestDescriptor(manifestDescDt)
+	}
+	return nil, nil
+}
+
+func getImageManifestDescriptor(exporterID string, resp *SolveResponse) (*ocispecs.Descriptor, error) {
 	if resp := resp.exporter(exporterID); resp != nil {
 		if manifestDescDt := resp.Data[exptypes.ExporterImageDescriptorKey]; manifestDescDt != "" {
-			return unmarshalManifestDescriptor(manifestDescDt)
+			return unmarshalEncodedManifestDescriptor(manifestDescDt)
 		}
 	}
 	if manifestDescDt := resp.ExporterResponse[exptypes.ExporterImageDescriptorKey]; manifestDescDt != "" {
-		return unmarshalManifestDescriptor(manifestDescDt)
+		return unmarshalEncodedManifestDescriptor(manifestDescDt)
 	}
 	return nil, nil
 }
 
-func unmarshalManifestDescriptor(manifestDesc string) (*ocispecs.Descriptor, error) {
-	manifestDescDt, err := base64.StdEncoding.DecodeString(manifestDesc)
+func unmarshalEncodedManifestDescriptor(base64Payload string) (*ocispecs.Descriptor, error) {
+	manifestDescDt, err := base64.StdEncoding.DecodeString(base64Payload)
 	if err != nil {
 		return nil, err
 	}
+	return unmarshalManifestDescriptor(string(manifestDescDt))
+}
+
+func unmarshalManifestDescriptor(manifestDescJSON string) (*ocispecs.Descriptor, error) {
 	var desc ocispecs.Descriptor
-	if err = json.Unmarshal([]byte(manifestDescDt), &desc); err != nil {
+	if err := json.Unmarshal([]byte(manifestDescJSON), &desc); err != nil {
 		return nil, err
 	}
 	return &desc, nil
@@ -502,13 +560,16 @@ func prepareSyncedFiles(def *llb.Definition, localMounts map[string]fsutil.FS) (
 	return result, nil
 }
 
-func ParseCacheOptions(ctx context.Context, opt *SolveOpt) error {
+func (opt *SolveOpt) parseCacheOptions(ctx context.Context) error {
+	if opt.s.cacheOpt != nil {
+		return nil
+	}
 	var (
 		cacheExports []*controlapi.CacheOptionsEntry
 		cacheImports []*controlapi.CacheOptionsEntry
 	)
 	contentStores := make(map[string]content.Store)
-	storesToUpdate := make(map[string]string)
+	storesToUpdate := make(map[string]ociStore)
 	frontendAttrs := make(map[string]string)
 	for _, ex := range opt.CacheExports {
 		if ex.Type == "local" {
@@ -529,8 +590,7 @@ func ParseCacheOptions(ctx context.Context, opt *SolveOpt) error {
 			if t, ok := ex.Attrs["tag"]; ok {
 				tag = t
 			}
-			// TODO(AkihiroSuda): support custom index JSON path and tag
-			storesToUpdate[csDir] = tag
+			storesToUpdate[ex.id] = ociStore{path: csDir, tag: tag}
 		}
 		if ex.Type == "registry" {
 			regRef := ex.Attrs["ref"]
@@ -541,6 +601,7 @@ func ParseCacheOptions(ctx context.Context, opt *SolveOpt) error {
 		cacheExports = append(cacheExports, &controlapi.CacheOptionsEntry{
 			Type:  ex.Type,
 			Attrs: ex.Attrs,
+			ID:    ex.id,
 		})
 	}
 	for _, im := range opt.CacheImports {