Merge pull request #2814 from jsternberg/bake-composable-attributes-phase2

bake: various fixes for composable attributes

bake/bake.go

@@ -698,30 +698,30 @@ type Target struct {
 	// Inherits is the only field that cannot be overridden with --set
 	Inherits []string `json:"inherits,omitempty" hcl:"inherits,optional" cty:"inherits"`
 
-	Annotations      []string                        `json:"annotations,omitempty" hcl:"annotations,optional" cty:"annotations"`
+	Annotations      []string                `json:"annotations,omitempty" hcl:"annotations,optional" cty:"annotations"`
-	Attest           []string                        `json:"attest,omitempty" hcl:"attest,optional" cty:"attest"`
+	Attest           []string                `json:"attest,omitempty" hcl:"attest,optional" cty:"attest"`
-	Context          *string                         `json:"context,omitempty" hcl:"context,optional" cty:"context"`
+	Context          *string                 `json:"context,omitempty" hcl:"context,optional" cty:"context"`
-	Contexts         map[string]string               `json:"contexts,omitempty" hcl:"contexts,optional" cty:"contexts"`
+	Contexts         map[string]string       `json:"contexts,omitempty" hcl:"contexts,optional" cty:"contexts"`
-	Dockerfile       *string                         `json:"dockerfile,omitempty" hcl:"dockerfile,optional" cty:"dockerfile"`
+	Dockerfile       *string                 `json:"dockerfile,omitempty" hcl:"dockerfile,optional" cty:"dockerfile"`
-	DockerfileInline *string                         `json:"dockerfile-inline,omitempty" hcl:"dockerfile-inline,optional" cty:"dockerfile-inline"`
+	DockerfileInline *string                 `json:"dockerfile-inline,omitempty" hcl:"dockerfile-inline,optional" cty:"dockerfile-inline"`
-	Args             map[string]*string              `json:"args,omitempty" hcl:"args,optional" cty:"args"`
+	Args             map[string]*string      `json:"args,omitempty" hcl:"args,optional" cty:"args"`
-	Labels           map[string]*string              `json:"labels,omitempty" hcl:"labels,optional" cty:"labels"`
+	Labels           map[string]*string      `json:"labels,omitempty" hcl:"labels,optional" cty:"labels"`
-	Tags             []string                        `json:"tags,omitempty" hcl:"tags,optional" cty:"tags"`
+	Tags             []string                `json:"tags,omitempty" hcl:"tags,optional" cty:"tags"`
-	CacheFrom        []*buildflags.CacheOptionsEntry `json:"cache-from,omitempty"  hcl:"cache-from,optional" cty:"cache-from"`
+	CacheFrom        buildflags.CacheOptions `json:"cache-from,omitempty"  hcl:"cache-from,optional" cty:"cache-from"`
-	CacheTo          []*buildflags.CacheOptionsEntry `json:"cache-to,omitempty"  hcl:"cache-to,optional" cty:"cache-to"`
+	CacheTo          buildflags.CacheOptions `json:"cache-to,omitempty"  hcl:"cache-to,optional" cty:"cache-to"`
-	Target           *string                         `json:"target,omitempty" hcl:"target,optional" cty:"target"`
+	Target           *string                 `json:"target,omitempty" hcl:"target,optional" cty:"target"`
-	Secrets          []*buildflags.Secret            `json:"secret,omitempty" hcl:"secret,optional" cty:"secret"`
+	Secrets          buildflags.Secrets      `json:"secret,omitempty" hcl:"secret,optional" cty:"secret"`
-	SSH              []*buildflags.SSH               `json:"ssh,omitempty" hcl:"ssh,optional" cty:"ssh"`
+	SSH              buildflags.SSHKeys      `json:"ssh,omitempty" hcl:"ssh,optional" cty:"ssh"`
-	Platforms        []string                        `json:"platforms,omitempty" hcl:"platforms,optional" cty:"platforms"`
+	Platforms        []string                `json:"platforms,omitempty" hcl:"platforms,optional" cty:"platforms"`
-	Outputs          []*buildflags.ExportEntry       `json:"output,omitempty" hcl:"output,optional" cty:"output"`
+	Outputs          buildflags.Exports      `json:"output,omitempty" hcl:"output,optional" cty:"output"`
-	Pull             *bool                           `json:"pull,omitempty" hcl:"pull,optional" cty:"pull"`
+	Pull             *bool                   `json:"pull,omitempty" hcl:"pull,optional" cty:"pull"`
-	NoCache          *bool                           `json:"no-cache,omitempty" hcl:"no-cache,optional" cty:"no-cache"`
+	NoCache          *bool                   `json:"no-cache,omitempty" hcl:"no-cache,optional" cty:"no-cache"`
-	NetworkMode      *string                         `json:"network,omitempty" hcl:"network,optional" cty:"network"`
+	NetworkMode      *string                 `json:"network,omitempty" hcl:"network,optional" cty:"network"`
-	NoCacheFilter    []string                        `json:"no-cache-filter,omitempty" hcl:"no-cache-filter,optional" cty:"no-cache-filter"`
+	NoCacheFilter    []string                `json:"no-cache-filter,omitempty" hcl:"no-cache-filter,optional" cty:"no-cache-filter"`
-	ShmSize          *string                         `json:"shm-size,omitempty" hcl:"shm-size,optional"`
+	ShmSize          *string                 `json:"shm-size,omitempty" hcl:"shm-size,optional"`
-	Ulimits          []string                        `json:"ulimits,omitempty" hcl:"ulimits,optional"`
+	Ulimits          []string                `json:"ulimits,omitempty" hcl:"ulimits,optional"`
-	Call             *string                         `json:"call,omitempty" hcl:"call,optional" cty:"call"`
+	Call             *string                 `json:"call,omitempty" hcl:"call,optional" cty:"call"`
-	Entitlements     []string                        `json:"entitlements,omitempty" hcl:"entitlements,optional" cty:"entitlements"`
+	Entitlements     []string                `json:"entitlements,omitempty" hcl:"entitlements,optional" cty:"entitlements"`
 	// IMPORTANT: if you add more fields here, do not forget to update newOverrides/AddOverrides and docs/bake-reference.md.
 
 	// linked is a private field to mark a target used as a linked one
@@ -739,12 +739,12 @@ func (t *Target) normalize() {
 	t.Annotations = removeDupesStr(t.Annotations)
 	t.Attest = removeAttestDupes(t.Attest)
 	t.Tags = removeDupesStr(t.Tags)
-	t.Secrets = removeDupes(t.Secrets)
+	t.Secrets = t.Secrets.Normalize()
-	t.SSH = removeDupes(t.SSH)
+	t.SSH = t.SSH.Normalize()
 	t.Platforms = removeDupesStr(t.Platforms)
-	t.CacheFrom = removeDupes(t.CacheFrom)
+	t.CacheFrom = t.CacheFrom.Normalize()
-	t.CacheTo = removeDupes(t.CacheTo)
+	t.CacheTo = t.CacheTo.Normalize()
-	t.Outputs = removeDupes(t.Outputs)
+	t.Outputs = t.Outputs.Normalize()
 	t.NoCacheFilter = removeDupesStr(t.NoCacheFilter)
 	t.Ulimits = removeDupesStr(t.Ulimits)
 
@@ -815,16 +815,16 @@ func (t *Target) Merge(t2 *Target) {
 		t.Attest = removeAttestDupes(t.Attest)
 	}
 	if t2.Secrets != nil { // merge
-		t.Secrets = append(t.Secrets, t2.Secrets...)
+		t.Secrets = t.Secrets.Merge(t2.Secrets)
 	}
 	if t2.SSH != nil { // merge
-		t.SSH = append(t.SSH, t2.SSH...)
+		t.SSH = t.SSH.Merge(t2.SSH)
 	}
 	if t2.Platforms != nil { // no merge
 		t.Platforms = t2.Platforms
 	}
 	if t2.CacheFrom != nil { // merge
-		t.CacheFrom = append(t.CacheFrom, t2.CacheFrom...)
+		t.CacheFrom = t.CacheFrom.Merge(t2.CacheFrom)
 	}
 	if t2.CacheTo != nil { // no merge
 		t.CacheTo = t2.CacheTo
@@ -1333,30 +1333,19 @@ func toBuildOpt(t *Target, inp *Input) (*build.Options, error) {
 	}
 	bo.Platforms = platforms
 
-	secrets := make([]*controllerapi.Secret, len(t.Secrets))
+	bo.SecretSpecs = t.Secrets.ToPB()
-	for i, s := range t.Secrets {
+	secretAttachment, err := controllerapi.CreateSecrets(bo.SecretSpecs)
-		secrets[i] = s.ToPB()
-	}
-	bo.SecretSpecs = secrets
-
-	secretAttachment, err := controllerapi.CreateSecrets(secrets)
 	if err != nil {
 		return nil, err
 	}
 	bo.Session = append(bo.Session, secretAttachment)
 
-	var sshSpecs []*controllerapi.SSH
+	bo.SSHSpecs = t.SSH.ToPB()
-	if len(t.SSH) > 0 {
+	if len(bo.SSHSpecs) == 0 && buildflags.IsGitSSH(bi.ContextPath) || (inp != nil && buildflags.IsGitSSH(inp.URL)) {
-		sshSpecs := make([]*controllerapi.SSH, len(t.SSH))
+		bo.SSHSpecs = []*controllerapi.SSH{{ID: "default"}}
-		for i, s := range t.SSH {
-			sshSpecs[i] = s.ToPB()
-		}
-	} else if buildflags.IsGitSSH(bi.ContextPath) || (inp != nil && buildflags.IsGitSSH(inp.URL)) {
-		sshSpecs = []*controllerapi.SSH{{ID: "default"}}
 	}
-	bo.SSHSpecs = sshSpecs
 
-	sshAttachment, err := controllerapi.CreateSSH(sshSpecs)
+	sshAttachment, err := controllerapi.CreateSSH(bo.SSHSpecs)
 	if err != nil {
 		return nil, err
 	}
@@ -1372,24 +1361,14 @@ func toBuildOpt(t *Target, inp *Input) (*build.Options, error) {
 		}
 	}
 
-	cacheImports := make([]*controllerapi.CacheOptionsEntry, len(t.CacheFrom))
+	if t.CacheFrom != nil {
-	for i, ci := range t.CacheFrom {
+		bo.CacheFrom = controllerapi.CreateCaches(t.CacheFrom.ToPB())
-		cacheImports[i] = ci.ToPB()
 	}
-	bo.CacheFrom = controllerapi.CreateCaches(cacheImports)
+	if t.CacheTo != nil {
-
+		bo.CacheTo = controllerapi.CreateCaches(t.CacheTo.ToPB())
-	cacheExports := make([]*controllerapi.CacheOptionsEntry, len(t.CacheTo))
-	for i, ce := range t.CacheTo {
-		cacheExports[i] = ce.ToPB()
-	}
-	bo.CacheTo = controllerapi.CreateCaches(cacheExports)
-
-	outputs := make([]*controllerapi.ExportEntry, len(t.Outputs))
-	for i, output := range t.Outputs {
-		outputs[i] = output.ToPB()
 	}
 
-	bo.Exports, bo.ExportsLocalPathsTemporary, err = controllerapi.CreateExports(outputs)
+	bo.Exports, bo.ExportsLocalPathsTemporary, err = controllerapi.CreateExports(t.Outputs.ToPB())
 	if err != nil {
 		return nil, err
 	}
@@ -1434,34 +1413,6 @@ func defaultTarget() *Target {
 	return &Target{}
 }
 
-type comparable[E any] interface {
-	Equal(other E) bool
-}
-
-func removeDupes[E comparable[E]](s []E) []E {
-	// Move backwards through the slice.
-	// For each element, any elements after the current element are unique.
-	// If we find our current element conflicts with an existing element,
-	// then we swap the offender with the end of the slice and chop it off.
-
-	// Start at the second to last element.
-	// The last element is always unique.
-	for i := len(s) - 2; i >= 0; i-- {
-		elem := s[i]
-		// Check for duplicates after our current element.
-		for j := i + 1; j < len(s); j++ {
-			if elem.Equal(s[j]) {
-				// Found a duplicate, exchange the
-				// duplicate with the last element.
-				s[j], s[len(s)-1] = s[len(s)-1], s[j]
-				s = s[:len(s)-1]
-				break
-			}
-		}
-	}
-	return s
-}
-
 func removeDupesStr(s []string) []string {
 	i := 0
 	seen := make(map[string]struct{}, len(s))
@@ -1616,6 +1567,10 @@ type arrValue[B any] interface {
 func parseArrValue[T any, PT arrValue[T]](s []string) ([]*T, error) {
 	outputs := make([]*T, 0, len(s))
 	for _, text := range s {
+		if text == "" {
+			continue
+		}
+
 		output := new(T)
 		if err := PT(output).UnmarshalText([]byte(text)); err != nil {
 			return nil, err
@@ -1625,9 +1580,13 @@ func parseArrValue[T any, PT arrValue[T]](s []string) ([]*T, error) {
 	return outputs, nil
 }
 
-func parseCacheArrValues(s []string) ([]*buildflags.CacheOptionsEntry, error) {
+func parseCacheArrValues(s []string) (buildflags.CacheOptions, error) {
-	outs := make([]*buildflags.CacheOptionsEntry, 0, len(s))
+	var outs buildflags.CacheOptions
 	for _, in := range s {
+		if in == "" {
+			continue
+		}
+
 		if !strings.Contains(in, "=") {
 			// This is ref only format. Each field in the CSV is its own entry.
 			fields, err := csvvalue.Fields(in, nil)

bake/bake_test.go

@@ -2019,6 +2019,26 @@ target "app" {
 	})
 }
 
+// https://github.com/docker/buildx/pull/428
+// https://github.com/docker/buildx/issues/2822
+func TestEmptyAttribute(t *testing.T) {
+	fp := File{
+		Name: "docker-bake.hcl",
+		Data: []byte(`
+target "app" {
+  output = [""]
+}
+`),
+	}
+
+	ctx := context.TODO()
+
+	m, _, err := ReadTargets(ctx, []File{fp}, []string{"app"}, nil, nil, &EntitlementConf{})
+	require.Equal(t, 1, len(m))
+	require.Len(t, m["app"].Outputs, 0)
+	require.NoError(t, err)
+}
+
 func stringify[V fmt.Stringer](values []V) []string {
 	s := make([]string, len(values))
 	for i, v := range values {

bake/compose.go

@@ -353,28 +353,28 @@ func (t *Target) composeExtTarget(exts map[string]interface{}) error {
 		if err != nil {
 			return err
 		}
-		t.CacheFrom = removeDupes(append(t.CacheFrom, cacheFrom...))
+		t.CacheFrom = t.CacheFrom.Merge(cacheFrom)
 	}
 	if len(xb.CacheTo) > 0 {
 		cacheTo, err := parseCacheArrValues(xb.CacheTo)
 		if err != nil {
 			return err
 		}
-		t.CacheTo = removeDupes(append(t.CacheTo, cacheTo...))
+		t.CacheTo = t.CacheTo.Merge(cacheTo)
 	}
 	if len(xb.Secrets) > 0 {
 		secrets, err := parseArrValue[buildflags.Secret](xb.Secrets)
 		if err != nil {
 			return err
 		}
-		t.Secrets = removeDupes(append(t.Secrets, secrets...))
+		t.Secrets = t.Secrets.Merge(secrets)
 	}
 	if len(xb.SSH) > 0 {
 		ssh, err := parseArrValue[buildflags.SSH](xb.SSH)
 		if err != nil {
 			return err
 		}
-		t.SSH = removeDupes(append(t.SSH, ssh...))
+		t.SSH = t.SSH.Merge(ssh)
 		slices.SortFunc(t.SSH, func(a, b *buildflags.SSH) int {
 			return a.Less(b)
 		})
@@ -387,7 +387,7 @@ func (t *Target) composeExtTarget(exts map[string]interface{}) error {
 		if err != nil {
 			return err
 		}
-		t.Outputs = removeDupes(append(t.Outputs, outputs...))
+		t.Outputs = t.Outputs.Merge(outputs)
 	}
 	if xb.Pull != nil {
 		t.Pull = xb.Pull

bake/hcl_test.go

@@ -606,7 +606,7 @@ func TestHCLAttrsCapsuleType(t *testing.T) {
 	target "app" {
 		cache-from = [
 			{ type = "registry", ref = "user/app:cache" },
-			{ type = "local", src = "path/to/cache" },
+			"type=local,src=path/to/cache",
 		]
 
 		cache-to = [
@@ -615,6 +615,7 @@ func TestHCLAttrsCapsuleType(t *testing.T) {
 
 		output = [
 			{ type = "oci", dest = "../out.tar" },
+			"type=local,dest=../out",
 		]
 
 		secret = [
@@ -633,7 +634,7 @@ func TestHCLAttrsCapsuleType(t *testing.T) {
 	require.NoError(t, err)
 
 	require.Equal(t, 1, len(c.Targets))
-	require.Equal(t, []string{"type=oci,dest=../out.tar"}, stringify(c.Targets[0].Outputs))
+	require.Equal(t, []string{"type=local,dest=../out", "type=oci,dest=../out.tar"}, stringify(c.Targets[0].Outputs))
 	require.Equal(t, []string{"type=local,src=path/to/cache", "user/app:cache"}, stringify(c.Targets[0].CacheFrom))
 	require.Equal(t, []string{"type=local,dest=path/to/cache"}, stringify(c.Targets[0].CacheTo))
 	require.Equal(t, []string{"id=mysecret,src=/local/secret", "id=mysecret2,env=TOKEN"}, stringify(c.Targets[0].Secrets))
@@ -649,13 +650,14 @@ func TestHCLAttrsCapsuleTypeVars(t *testing.T) {
 	target "app" {
 		cache-from = [
 			{ type = "registry", ref = "user/app:cache" },
-			{ type = "local", src = "path/to/cache" },
+			"type=local,src=path/to/cache",
 		]
 
 		cache-to = [ target.app.cache-from[0] ]
 
 		output = [
 			{ type = "oci", dest = "../out.tar" },
+			"type=local,dest=../out",
 		]
 
 		secret = [
@@ -674,7 +676,7 @@ func TestHCLAttrsCapsuleTypeVars(t *testing.T) {
 		output = [ "type=oci,dest=../${foo}.tar" ]
 
 		secret = [
-			{ id = target.app.output[0].type, src = "/local/secret" },
+			{ id = target.app.output[0].type, src = "/${target.app.cache-from[1].type}/secret" },
 		]
 	}
 	`)
@@ -696,7 +698,7 @@ func TestHCLAttrsCapsuleTypeVars(t *testing.T) {
 	}
 
 	app := findTarget(t, "app")
-	require.Equal(t, []string{"type=oci,dest=../out.tar"}, stringify(app.Outputs))
+	require.Equal(t, []string{"type=local,dest=../out", "type=oci,dest=../out.tar"}, stringify(app.Outputs))
 	require.Equal(t, []string{"type=local,src=path/to/cache", "user/app:cache"}, stringify(app.CacheFrom))
 	require.Equal(t, []string{"user/app:cache"}, stringify(app.CacheTo))
 	require.Equal(t, []string{"id=mysecret,src=/local/secret"}, stringify(app.Secrets))

bake/hclparser/type_implied_ext.go

@@ -10,44 +10,60 @@ import (
 	"github.com/zclconf/go-cty/cty/gocty"
 )
 
-type CapsuleValue interface {
+type ToCtyValueConverter interface {
-	// FromCtyValue will initialize this value using a cty.Value.
-	FromCtyValue(in cty.Value, path cty.Path) error
-
 	// ToCtyValue will convert this capsule value into a native
 	// cty.Value. This should not return a capsule type.
 	ToCtyValue() cty.Value
 }
 
+type FromCtyValueConverter interface {
+	// FromCtyValue will initialize this value using a cty.Value.
+	FromCtyValue(in cty.Value, path cty.Path) error
+}
+
 type extensionType int
 
 const (
-	nativeTypeExtension extensionType = iota
+	unwrapCapsuleValueExtension extensionType = iota
 )
 
 func impliedTypeExt(rt reflect.Type, _ cty.Path) (cty.Type, error) {
-	if rt.AssignableTo(capsuleValueType) {
+	if rt.Kind() != reflect.Pointer {
+		rt = reflect.PointerTo(rt)
+	}
+
+	if isCapsuleType(rt) {
 		return capsuleValueCapsuleType(rt), nil
 	}
 	return cty.NilType, errdefs.ErrNotImplemented
 }
 
-var (
+func isCapsuleType(rt reflect.Type) bool {
-	capsuleValueType  = reflect.TypeFor[CapsuleValue]()
+	fromCtyValueType := reflect.TypeFor[FromCtyValueConverter]()
-	capsuleValueTypes sync.Map
+	toCtyValueType := reflect.TypeFor[ToCtyValueConverter]()
-)
+	return rt.Implements(fromCtyValueType) && rt.Implements(toCtyValueType)
+}
+
+var capsuleValueTypes sync.Map
 
 func capsuleValueCapsuleType(rt reflect.Type) cty.Type {
-	if val, loaded := capsuleValueTypes.Load(rt); loaded {
+	if rt.Kind() != reflect.Pointer {
+		panic("capsule value must be a pointer")
+	}
+
+	elem := rt.Elem()
+	if val, loaded := capsuleValueTypes.Load(elem); loaded {
 		return val.(cty.Type)
 	}
 
-	// First time used.
+	toCtyValueType := reflect.TypeFor[ToCtyValueConverter]()
-	ety := cty.CapsuleWithOps(rt.Name(), rt.Elem(), &cty.CapsuleOps{
+
+	// First time used. Initialize new capsule ops.
+	ops := &cty.CapsuleOps{
 		ConversionTo: func(_ cty.Type) func(cty.Value, cty.Path) (any, error) {
 			return func(in cty.Value, p cty.Path) (any, error) {
-				rv := reflect.New(rt.Elem()).Interface()
+				rv := reflect.New(elem).Interface()
-				if err := rv.(CapsuleValue).FromCtyValue(in, p); err != nil {
+				if err := rv.(FromCtyValueConverter).FromCtyValue(in, p); err != nil {
 					return nil, err
 				}
 				return rv, nil
@@ -55,30 +71,39 @@ func capsuleValueCapsuleType(rt reflect.Type) cty.Type {
 		},
 		ConversionFrom: func(want cty.Type) func(any, cty.Path) (cty.Value, error) {
 			return func(in any, _ cty.Path) (cty.Value, error) {
-				v := in.(CapsuleValue).ToCtyValue()
+				rv := reflect.ValueOf(in).Convert(toCtyValueType)
+				v := rv.Interface().(ToCtyValueConverter).ToCtyValue()
 				return convert.Convert(v, want)
 			}
 		},
 		ExtensionData: func(key any) any {
 			switch key {
-			case nativeTypeExtension:
+			case unwrapCapsuleValueExtension:
-				zero := reflect.Zero(rt).Interface()
+				zero := reflect.Zero(elem).Interface()
-				return zero.(CapsuleValue).ToCtyValue().Type()
+				if conv, ok := zero.(ToCtyValueConverter); ok {
-			default:
+					return conv.ToCtyValue().Type()
-				return nil
+				}
-			}
-		},
-	})
 
-	// Attempt to store the new type. Use whichever was loaded first in the case of a race condition.
+				zero = reflect.Zero(rt).Interface()
-	val, _ := capsuleValueTypes.LoadOrStore(rt, ety)
+				if conv, ok := zero.(ToCtyValueConverter); ok {
+					return conv.ToCtyValue().Type()
+				}
+			}
+			return nil
+		},
+	}
+
+	// Attempt to store the new type. Use whichever was loaded first in the case
+	// of a race condition.
+	ety := cty.CapsuleWithOps(elem.Name(), elem, ops)
+	val, _ := capsuleValueTypes.LoadOrStore(elem, ety)
 	return val.(cty.Type)
 }
 
-// ToNativeValue will convert a value to only native cty types which will
+// UnwrapCtyValue will unwrap capsule type values into their native cty value
-// remove capsule types if possible.
+// equivalents if possible.
-func ToNativeValue(in cty.Value) cty.Value {
+func UnwrapCtyValue(in cty.Value) cty.Value {
-	want := toNativeType(in.Type())
+	want := toCtyValueType(in.Type())
 	if in.Type().Equals(want) {
 		return in
 	} else if out, err := convert.Convert(in, want); err == nil {
@@ -87,17 +112,17 @@ func ToNativeValue(in cty.Value) cty.Value {
 	return cty.NullVal(want)
 }
 
-func toNativeType(in cty.Type) cty.Type {
+func toCtyValueType(in cty.Type) cty.Type {
 	if et := in.MapElementType(); et != nil {
-		return cty.Map(toNativeType(*et))
+		return cty.Map(toCtyValueType(*et))
 	}
 
 	if et := in.SetElementType(); et != nil {
-		return cty.Set(toNativeType(*et))
+		return cty.Set(toCtyValueType(*et))
 	}
 
 	if et := in.ListElementType(); et != nil {
-		return cty.List(toNativeType(*et))
+		return cty.List(toCtyValueType(*et))
 	}
 
 	if in.IsObjectType() {
@@ -105,7 +130,7 @@ func toNativeType(in cty.Type) cty.Type {
 		inAttrTypes := in.AttributeTypes()
 		outAttrTypes := make(map[string]cty.Type, len(inAttrTypes))
 		for name, typ := range inAttrTypes {
-			outAttrTypes[name] = toNativeType(typ)
+			outAttrTypes[name] = toCtyValueType(typ)
 			if in.AttributeOptional(name) {
 				optional = append(optional, name)
 			}
@@ -117,13 +142,13 @@ func toNativeType(in cty.Type) cty.Type {
 		inTypes := in.TupleElementTypes()
 		outTypes := make([]cty.Type, len(inTypes))
 		for i, typ := range inTypes {
-			outTypes[i] = toNativeType(typ)
+			outTypes[i] = toCtyValueType(typ)
 		}
 		return cty.Tuple(outTypes)
 	}
 
 	if in.IsCapsuleType() {
-		if out := in.CapsuleExtensionData(nativeTypeExtension); out != nil {
+		if out := in.CapsuleExtensionData(unwrapCapsuleValueExtension); out != nil {
 			return out.(cty.Type)
 		}
 		return cty.DynamicPseudoType
@@ -137,5 +162,5 @@ func ToCtyValue(val any, ty cty.Type) (cty.Value, error) {
 	if err != nil {
 		return out, err
 	}
-	return ToNativeValue(out), nil
+	return UnwrapCtyValue(out), nil
 }

tests/bake.go

@@ -33,6 +33,7 @@ func bakeCmd(sb integration.Sandbox, opts ...cmdOpt) (string, error) {
 
 var bakeTests = []func(t *testing.T, sb integration.Sandbox){
 	testBakePrint,
+	testBakePrintSensitive,
 	testBakeLocal,
 	testBakeLocalMulti,
 	testBakeRemote,
@@ -86,7 +87,8 @@ target "build" {
     HELLO = "foo"
   }
 }
-`)},
+`),
+		},
 		{
 			"Compose",
 			"compose.yml",
@@ -97,7 +99,8 @@ services:
       context: .
       args:
         HELLO: foo
-`)},
+`),
+		},
 	}
 
 	for _, tc := range testCases {
@@ -158,6 +161,125 @@ RUN echo "Hello ${HELLO}"
 	}
 }
 
+func testBakePrintSensitive(t *testing.T, sb integration.Sandbox) {
+	testCases := []struct {
+		name string
+		f    string
+		dt   []byte
+	}{
+		{
+			"HCL",
+			"docker-bake.hcl",
+			[]byte(`
+target "build" {
+  args = {
+    HELLO = "foo"
+  }
+
+  cache-from = [
+    "type=gha,token=abc",
+    "type=s3,region=us-west-2,bucket=my_bucket,name=my_image",
+  ]
+}
+`),
+		},
+		{
+			"Compose",
+			"compose.yml",
+			[]byte(`
+services:
+  build:
+    build:
+      context: .
+      args:
+        HELLO: foo
+      cache_from:
+        - type=gha,token=abc
+        - type=s3,region=us-west-2,bucket=my_bucket,name=my_image
+`),
+		},
+	}
+
+	for _, tc := range testCases {
+		t.Run(tc.name, func(t *testing.T) {
+			dir := tmpdir(
+				t,
+				fstest.CreateFile(tc.f, tc.dt, 0600),
+				fstest.CreateFile("Dockerfile", []byte(`
+FROM busybox
+ARG HELLO
+RUN echo "Hello ${HELLO}"
+	`), 0600),
+			)
+
+			cmd := buildxCmd(sb, withDir(dir), withArgs("bake", "--print", "build"),
+				withEnv(
+					"ACTIONS_RUNTIME_TOKEN=sensitive_token",
+					"ACTIONS_CACHE_URL=https://cache.github.com",
+					"AWS_ACCESS_KEY_ID=definitely_dont_look_here",
+					"AWS_SECRET_ACCESS_KEY=hackers_please_dont_steal",
+					"AWS_SESSION_TOKEN=not_a_mitm_attack",
+				),
+			)
+			stdout := bytes.Buffer{}
+			stderr := bytes.Buffer{}
+			cmd.Stdout = &stdout
+			cmd.Stderr = &stderr
+			require.NoError(t, cmd.Run(), stdout.String(), stderr.String())
+
+			var def struct {
+				Group  map[string]*bake.Group  `json:"group,omitempty"`
+				Target map[string]*bake.Target `json:"target"`
+			}
+			require.NoError(t, json.Unmarshal(stdout.Bytes(), &def))
+
+			require.Len(t, def.Group, 1)
+			require.Contains(t, def.Group, "default")
+
+			require.Equal(t, []string{"build"}, def.Group["default"].Targets)
+			require.Len(t, def.Target, 1)
+			require.Contains(t, def.Target, "build")
+			require.Equal(t, ".", *def.Target["build"].Context)
+			require.Equal(t, "Dockerfile", *def.Target["build"].Dockerfile)
+			require.Equal(t, map[string]*string{"HELLO": ptrstr("foo")}, def.Target["build"].Args)
+			require.NotNil(t, def.Target["build"].CacheFrom)
+			require.Len(t, def.Target["build"].CacheFrom, 2)
+
+			require.JSONEq(t, `{
+  "group": {
+    "default": {
+      "targets": [
+        "build"
+      ]
+    }
+  },
+  "target": {
+    "build": {
+      "context": ".",
+      "dockerfile": "Dockerfile",
+      "args": {
+        "HELLO": "foo"
+      },
+      "cache-from": [
+        {
+          "type": "gha",
+          "token": "abc"
+        },
+        {
+          "type": "s3",
+          "region": "us-west-2",
+          "bucket": "my_bucket",
+          "name": "my_image"
+        }
+      ]
+    }
+  }
+}
+`, stdout.String())
+		})
+	}
+}
+
 func testBakeLocal(t *testing.T, sb integration.Sandbox) {
 	dockerfile := []byte(`
 FROM scratch

util/buildflags/attests.go

@@ -21,7 +21,7 @@ func CanonicalizeAttest(attestType string, in string) string {
 }
 
 func ParseAttests(in []string) ([]*controllerapi.Attest, error) {
-	out := []*controllerapi.Attest{}
+	var out []*controllerapi.Attest
 	found := map[string]struct{}{}
 	for _, in := range in {
 		in := in

util/buildflags/cache.go

@@ -15,6 +15,41 @@ import (
 	jsoncty "github.com/zclconf/go-cty/cty/json"
 )
 
+type CacheOptions []*CacheOptionsEntry
+
+func (o CacheOptions) Merge(other CacheOptions) CacheOptions {
+	if other == nil {
+		return o.Normalize()
+	} else if o == nil {
+		return other.Normalize()
+	}
+
+	return append(o, other...).Normalize()
+}
+
+func (o CacheOptions) Normalize() CacheOptions {
+	if len(o) == 0 {
+		return nil
+	}
+	return removeDupes(o)
+}
+
+func (o CacheOptions) ToPB() []*controllerapi.CacheOptionsEntry {
+	if len(o) == 0 {
+		return nil
+	}
+
+	var outs []*controllerapi.CacheOptionsEntry
+	for _, entry := range o {
+		pb := entry.ToPB()
+		if !isActive(pb) {
+			continue
+		}
+		outs = append(outs, pb)
+	}
+	return outs
+}
+
 type CacheOptionsEntry struct {
 	Type  string            `json:"type"`
 	Attrs map[string]string `json:"attrs,omitempty"`
@@ -46,10 +81,13 @@ func (e *CacheOptionsEntry) String() string {
 }
 
 func (e *CacheOptionsEntry) ToPB() *controllerapi.CacheOptionsEntry {
-	return &controllerapi.CacheOptionsEntry{
+	ci := &controllerapi.CacheOptionsEntry{
 		Type:  e.Type,
 		Attrs: maps.Clone(e.Attrs),
 	}
+	addGithubToken(ci)
+	addAwsCredentials(ci)
+	return ci
 }
 
 func (e *CacheOptionsEntry) MarshalJSON() ([]byte, error) {
@@ -74,14 +112,6 @@ func (e *CacheOptionsEntry) UnmarshalJSON(data []byte) error {
 	return e.validate(data)
 }
 
-func (e *CacheOptionsEntry) IsActive() bool {
-	// Always active if not gha.
-	if e.Type != "gha" {
-		return true
-	}
-	return e.Attrs["token"] != "" && e.Attrs["url"] != ""
-}
-
 func (e *CacheOptionsEntry) UnmarshalText(text []byte) error {
 	in := string(text)
 	fields, err := csvvalue.Fields(in, nil)
@@ -116,8 +146,6 @@ func (e *CacheOptionsEntry) UnmarshalText(text []byte) error {
 	if e.Type == "" {
 		return errors.Errorf("type required form> %q", in)
 	}
-	addGithubToken(e)
-	addAwsCredentials(e)
 	return e.validate(text)
 }
 
@@ -140,23 +168,22 @@ func (e *CacheOptionsEntry) validate(gv interface{}) error {
 }
 
 func ParseCacheEntry(in []string) ([]*controllerapi.CacheOptionsEntry, error) {
-	outs := make([]*controllerapi.CacheOptionsEntry, 0, len(in))
+	if len(in) == 0 {
+		return nil, nil
+	}
+
+	opts := make(CacheOptions, 0, len(in))
 	for _, in := range in {
 		var out CacheOptionsEntry
 		if err := out.UnmarshalText([]byte(in)); err != nil {
 			return nil, err
 		}
-
+		opts = append(opts, &out)
-		if !out.IsActive() {
-			// Skip inactive cache entries.
-			continue
-		}
-		outs = append(outs, out.ToPB())
 	}
-	return outs, nil
+	return opts.ToPB(), nil
 }
 
-func addGithubToken(ci *CacheOptionsEntry) {
+func addGithubToken(ci *controllerapi.CacheOptionsEntry) {
 	if ci.Type != "gha" {
 		return
 	}
@@ -172,7 +199,7 @@ func addGithubToken(ci *CacheOptionsEntry) {
 	}
 }
 
-func addAwsCredentials(ci *CacheOptionsEntry) {
+func addAwsCredentials(ci *controllerapi.CacheOptionsEntry) {
 	if ci.Type != "s3" {
 		return
 	}
@@ -201,3 +228,11 @@ func addAwsCredentials(ci *CacheOptionsEntry) {
 		ci.Attrs["session_token"] = credentials.SessionToken
 	}
 }
+
+func isActive(pb *controllerapi.CacheOptionsEntry) bool {
+	// Always active if not gha.
+	if pb.Type != "gha" {
+		return true
+	}
+	return pb.Attrs["token"] != "" && pb.Attrs["url"] != ""
+}

util/buildflags/cache_cty.go

@@ -0,0 +1,86 @@
+package buildflags
+
+import (
+	"sync"
+
+	"github.com/zclconf/go-cty/cty"
+	"github.com/zclconf/go-cty/cty/convert"
+)
+
+var cacheOptionsEntryType = sync.OnceValue(func() cty.Type {
+	return cty.Map(cty.String)
+})
+
+func (o *CacheOptions) FromCtyValue(in cty.Value, p cty.Path) error {
+	got := in.Type()
+	if got.IsTupleType() || got.IsListType() {
+		return o.fromCtyValue(in, p)
+	}
+
+	want := cty.List(cacheOptionsEntryType())
+	return p.NewErrorf("%s", convert.MismatchMessage(got, want))
+}
+
+func (o *CacheOptions) fromCtyValue(in cty.Value, p cty.Path) error {
+	*o = make([]*CacheOptionsEntry, 0, in.LengthInt())
+	for elem := in.ElementIterator(); elem.Next(); {
+		_, value := elem.Element()
+
+		if isEmpty(value) {
+			continue
+		}
+
+		entry := &CacheOptionsEntry{}
+		if err := entry.FromCtyValue(value, p); err != nil {
+			return err
+		}
+		*o = append(*o, entry)
+	}
+	return nil
+}
+
+func (o CacheOptions) ToCtyValue() cty.Value {
+	if len(o) == 0 {
+		return cty.ListValEmpty(cacheOptionsEntryType())
+	}
+
+	vals := make([]cty.Value, len(o))
+	for i, entry := range o {
+		vals[i] = entry.ToCtyValue()
+	}
+	return cty.ListVal(vals)
+}
+
+func (o *CacheOptionsEntry) FromCtyValue(in cty.Value, p cty.Path) error {
+	if in.Type() == cty.String {
+		if err := o.UnmarshalText([]byte(in.AsString())); err != nil {
+			return p.NewError(err)
+		}
+		return nil
+	}
+
+	conv, err := convert.Convert(in, cty.Map(cty.String))
+	if err != nil {
+		return err
+	}
+
+	m := conv.AsValueMap()
+	if err := getAndDelete(m, "type", &o.Type); err != nil {
+		return err
+	}
+	o.Attrs = asMap(m)
+	return o.validate(in)
+}
+
+func (o *CacheOptionsEntry) ToCtyValue() cty.Value {
+	if o == nil {
+		return cty.NullVal(cty.Map(cty.String))
+	}
+
+	vals := make(map[string]cty.Value, len(o.Attrs)+1)
+	for k, v := range o.Attrs {
+		vals[k] = cty.StringVal(v)
+	}
+	vals["type"] = cty.StringVal(o.Type)
+	return cty.MapVal(vals)
+}

util/buildflags/cache_test.go

@@ -0,0 +1,39 @@
+package buildflags
+
+import (
+	"testing"
+
+	"github.com/docker/buildx/controller/pb"
+	"github.com/stretchr/testify/require"
+)
+
+func TestCacheOptions_DerivedVars(t *testing.T) {
+	t.Setenv("ACTIONS_RUNTIME_TOKEN", "sensitive_token")
+	t.Setenv("ACTIONS_CACHE_URL", "https://cache.github.com")
+	t.Setenv("AWS_ACCESS_KEY_ID", "definitely_dont_look_here")
+	t.Setenv("AWS_SECRET_ACCESS_KEY", "hackers_please_dont_steal")
+	t.Setenv("AWS_SESSION_TOKEN", "not_a_mitm_attack")
+
+	cacheFrom, err := ParseCacheEntry([]string{"type=gha", "type=s3,region=us-west-2,bucket=my_bucket,name=my_image"})
+	require.NoError(t, err)
+	require.Equal(t, []*pb.CacheOptionsEntry{
+		{
+			Type: "gha",
+			Attrs: map[string]string{
+				"token": "sensitive_token",
+				"url":   "https://cache.github.com",
+			},
+		},
+		{
+			Type: "s3",
+			Attrs: map[string]string{
+				"region":            "us-west-2",
+				"bucket":            "my_bucket",
+				"name":              "my_image",
+				"access_key_id":     "definitely_dont_look_here",
+				"secret_access_key": "hackers_please_dont_steal",
+				"session_token":     "not_a_mitm_attack",
+			},
+		},
+	}, cacheFrom)
+}

util/buildflags/context.go

@@ -11,8 +11,13 @@ func ParseContextNames(values []string) (map[string]string, error) {
 	if len(values) == 0 {
 		return nil, nil
 	}
+
 	result := make(map[string]string, len(values))
 	for _, value := range values {
+		if value == "" {
+			continue
+		}
+
 		kv := strings.SplitN(value, "=", 2)
 		if len(kv) != 2 {
 			return nil, errors.Errorf("invalid context value: %s, expected key=value", value)

util/buildflags/cty.go

@@ -1,183 +0,0 @@
-package buildflags
-
-import (
-	"encoding"
-	"sync"
-
-	"github.com/zclconf/go-cty/cty"
-	"github.com/zclconf/go-cty/cty/convert"
-	"github.com/zclconf/go-cty/cty/gocty"
-)
-
-func (e *CacheOptionsEntry) FromCtyValue(in cty.Value, p cty.Path) error {
-	conv, err := convert.Convert(in, cty.Map(cty.String))
-	if err == nil {
-		m := conv.AsValueMap()
-		if err := getAndDelete(m, "type", &e.Type); err != nil {
-			return err
-		}
-		e.Attrs = asMap(m)
-		return e.validate(in)
-	}
-	return unmarshalTextFallback(in, e, err)
-}
-
-func (e *CacheOptionsEntry) ToCtyValue() cty.Value {
-	if e == nil {
-		return cty.NullVal(cty.Map(cty.String))
-	}
-
-	vals := make(map[string]cty.Value, len(e.Attrs)+1)
-	for k, v := range e.Attrs {
-		vals[k] = cty.StringVal(v)
-	}
-	vals["type"] = cty.StringVal(e.Type)
-	return cty.MapVal(vals)
-}
-
-func (e *ExportEntry) FromCtyValue(in cty.Value, p cty.Path) error {
-	conv, err := convert.Convert(in, cty.Map(cty.String))
-	if err == nil {
-		m := conv.AsValueMap()
-		if err := getAndDelete(m, "type", &e.Type); err != nil {
-			return err
-		}
-		if err := getAndDelete(m, "dest", &e.Destination); err != nil {
-			return err
-		}
-		e.Attrs = asMap(m)
-		return e.validate()
-	}
-	return unmarshalTextFallback(in, e, err)
-}
-
-func (e *ExportEntry) ToCtyValue() cty.Value {
-	if e == nil {
-		return cty.NullVal(cty.Map(cty.String))
-	}
-
-	vals := make(map[string]cty.Value, len(e.Attrs)+2)
-	for k, v := range e.Attrs {
-		vals[k] = cty.StringVal(v)
-	}
-	vals["type"] = cty.StringVal(e.Type)
-	vals["dest"] = cty.StringVal(e.Destination)
-	return cty.MapVal(vals)
-}
-
-var secretType = sync.OnceValue(func() cty.Type {
-	return cty.ObjectWithOptionalAttrs(
-		map[string]cty.Type{
-			"id":  cty.String,
-			"src": cty.String,
-			"env": cty.String,
-		},
-		[]string{"id", "src", "env"},
-	)
-})
-
-func (e *Secret) FromCtyValue(in cty.Value, p cty.Path) (err error) {
-	conv, err := convert.Convert(in, secretType())
-	if err == nil {
-		if id := conv.GetAttr("id"); !id.IsNull() {
-			e.ID = id.AsString()
-		}
-		if src := conv.GetAttr("src"); !src.IsNull() {
-			e.FilePath = src.AsString()
-		}
-		if env := conv.GetAttr("env"); !env.IsNull() {
-			e.Env = env.AsString()
-		}
-		return nil
-	}
-	return unmarshalTextFallback(in, e, err)
-}
-
-func (e *Secret) ToCtyValue() cty.Value {
-	if e == nil {
-		return cty.NullVal(secretType())
-	}
-
-	return cty.ObjectVal(map[string]cty.Value{
-		"id":  cty.StringVal(e.ID),
-		"src": cty.StringVal(e.FilePath),
-		"env": cty.StringVal(e.Env),
-	})
-}
-
-var sshType = sync.OnceValue(func() cty.Type {
-	return cty.ObjectWithOptionalAttrs(
-		map[string]cty.Type{
-			"id":    cty.String,
-			"paths": cty.List(cty.String),
-		},
-		[]string{"id", "paths"},
-	)
-})
-
-func (e *SSH) FromCtyValue(in cty.Value, p cty.Path) (err error) {
-	conv, err := convert.Convert(in, sshType())
-	if err == nil {
-		if id := conv.GetAttr("id"); !id.IsNull() {
-			e.ID = id.AsString()
-		}
-		if paths := conv.GetAttr("paths"); !paths.IsNull() {
-			if err := gocty.FromCtyValue(paths, &e.Paths); err != nil {
-				return err
-			}
-		}
-		return nil
-	}
-	return unmarshalTextFallback(in, e, err)
-}
-
-func (e *SSH) ToCtyValue() cty.Value {
-	if e == nil {
-		return cty.NullVal(sshType())
-	}
-
-	var ctyPaths cty.Value
-	if len(e.Paths) > 0 {
-		paths := make([]cty.Value, len(e.Paths))
-		for i, path := range e.Paths {
-			paths[i] = cty.StringVal(path)
-		}
-		ctyPaths = cty.ListVal(paths)
-	} else {
-		ctyPaths = cty.ListValEmpty(cty.String)
-	}
-
-	return cty.ObjectVal(map[string]cty.Value{
-		"id":    cty.StringVal(e.ID),
-		"paths": ctyPaths,
-	})
-}
-
-func getAndDelete(m map[string]cty.Value, attr string, gv interface{}) error {
-	if v, ok := m[attr]; ok {
-		delete(m, attr)
-		return gocty.FromCtyValue(v, gv)
-	}
-	return nil
-}
-
-func asMap(m map[string]cty.Value) map[string]string {
-	out := make(map[string]string, len(m))
-	for k, v := range m {
-		out[k] = v.AsString()
-	}
-	return out
-}
-
-func unmarshalTextFallback[V encoding.TextUnmarshaler](in cty.Value, v V, inErr error) (outErr error) {
-	// Attempt to convert this type to a string.
-	conv, err := convert.Convert(in, cty.String)
-	if err != nil {
-		// Cannot convert. Do not attempt to convert and return the original error.
-		return inErr
-	}
-
-	// Conversion was successful. Use UnmarshalText on the string and return any
-	// errors associated with that.
-	return v.UnmarshalText([]byte(conv.AsString()))
-}

util/buildflags/entitlements.go

@@ -5,6 +5,10 @@ import "github.com/moby/buildkit/util/entitlements"
 func ParseEntitlements(in []string) ([]entitlements.Entitlement, error) {
 	out := make([]entitlements.Entitlement, 0, len(in))
 	for _, v := range in {
+		if v == "" {
+			continue
+		}
+
 		e, err := entitlements.Parse(v)
 		if err != nil {
 			return nil, err

util/buildflags/export.go

@@ -16,6 +16,39 @@ import (
 	"github.com/tonistiigi/go-csvvalue"
 )
 
+type Exports []*ExportEntry
+
+func (e Exports) Merge(other Exports) Exports {
+	if other == nil {
+		e.Normalize()
+		return e
+	} else if e == nil {
+		other.Normalize()
+		return other
+	}
+
+	return append(e, other...).Normalize()
+}
+
+func (e Exports) Normalize() Exports {
+	if len(e) == 0 {
+		return nil
+	}
+	return removeDupes(e)
+}
+
+func (e Exports) ToPB() []*controllerapi.ExportEntry {
+	if len(e) == 0 {
+		return nil
+	}
+
+	entries := make([]*controllerapi.ExportEntry, len(e))
+	for i, entry := range e {
+		entries[i] = entry.ToPB()
+	}
+	return entries
+}
+
 type ExportEntry struct {
 	Type        string            `json:"type"`
 	Attrs       map[string]string `json:"attrs,omitempty"`
@@ -131,18 +164,23 @@ func (e *ExportEntry) validate() error {
 }
 
 func ParseExports(inp []string) ([]*controllerapi.ExportEntry, error) {
-	var outs []*controllerapi.ExportEntry
 	if len(inp) == 0 {
 		return nil, nil
 	}
+
+	export := make(Exports, 0, len(inp))
 	for _, s := range inp {
+		if s == "" {
+			continue
+		}
+
 		var out ExportEntry
 		if err := out.UnmarshalText([]byte(s)); err != nil {
 			return nil, err
 		}
-		outs = append(outs, out.ToPB())
+		export = append(export, &out)
 	}
-	return outs, nil
+	return export.ToPB(), nil
 }
 
 func ParseAnnotations(inp []string) (map[exptypes.AnnotationKey]string, error) {
@@ -153,6 +191,10 @@ func ParseAnnotations(inp []string) (map[exptypes.AnnotationKey]string, error) {
 
 	annotations := make(map[exptypes.AnnotationKey]string)
 	for _, inp := range inp {
+		if inp == "" {
+			continue
+		}
+
 		k, v, ok := strings.Cut(inp, "=")
 		if !ok {
 			return nil, errors.Errorf("invalid annotation %q, expected key=value", inp)

util/buildflags/export_cty.go

@@ -0,0 +1,90 @@
+package buildflags
+
+import (
+	"sync"
+
+	"github.com/zclconf/go-cty/cty"
+	"github.com/zclconf/go-cty/cty/convert"
+)
+
+var exportEntryType = sync.OnceValue(func() cty.Type {
+	return cty.Map(cty.String)
+})
+
+func (e *Exports) FromCtyValue(in cty.Value, p cty.Path) error {
+	got := in.Type()
+	if got.IsTupleType() || got.IsListType() {
+		return e.fromCtyValue(in, p)
+	}
+
+	want := cty.List(exportEntryType())
+	return p.NewErrorf("%s", convert.MismatchMessage(got, want))
+}
+
+func (e *Exports) fromCtyValue(in cty.Value, p cty.Path) error {
+	*e = make([]*ExportEntry, 0, in.LengthInt())
+	for elem := in.ElementIterator(); elem.Next(); {
+		_, value := elem.Element()
+
+		if isEmpty(value) {
+			continue
+		}
+
+		entry := &ExportEntry{}
+		if err := entry.FromCtyValue(value, p); err != nil {
+			return err
+		}
+		*e = append(*e, entry)
+	}
+	return nil
+}
+
+func (e Exports) ToCtyValue() cty.Value {
+	if len(e) == 0 {
+		return cty.ListValEmpty(exportEntryType())
+	}
+
+	vals := make([]cty.Value, len(e))
+	for i, entry := range e {
+		vals[i] = entry.ToCtyValue()
+	}
+	return cty.ListVal(vals)
+}
+
+func (e *ExportEntry) FromCtyValue(in cty.Value, p cty.Path) error {
+	if in.Type() == cty.String {
+		if err := e.UnmarshalText([]byte(in.AsString())); err != nil {
+			return p.NewError(err)
+		}
+		return nil
+	}
+
+	conv, err := convert.Convert(in, cty.Map(cty.String))
+	if err != nil {
+		return err
+	}
+
+	m := conv.AsValueMap()
+	if err := getAndDelete(m, "type", &e.Type); err != nil {
+		return err
+	}
+	if err := getAndDelete(m, "dest", &e.Destination); err != nil {
+		return err
+	}
+	e.Attrs = asMap(m)
+	return e.validate()
+}
+
+func (e *ExportEntry) ToCtyValue() cty.Value {
+	if e == nil {
+		return cty.NullVal(cty.Map(cty.String))
+	}
+
+	vals := make(map[string]cty.Value, len(e.Attrs)+2)
+	for k, v := range e.Attrs {
+		vals[k] = cty.StringVal(v)
+	}
+	vals["type"] = cty.StringVal(e.Type)
+	vals["dest"] = cty.StringVal(e.Destination)
+	return cty.MapVal(vals)
+}

util/buildflags/secrets.go

@@ -8,6 +8,39 @@ import (
 	"github.com/tonistiigi/go-csvvalue"
 )
 
+type Secrets []*Secret
+
+func (s Secrets) Merge(other Secrets) Secrets {
+	if other == nil {
+		s.Normalize()
+		return s
+	} else if s == nil {
+		other.Normalize()
+		return other
+	}
+
+	return append(s, other...).Normalize()
+}
+
+func (s Secrets) Normalize() Secrets {
+	if len(s) == 0 {
+		return nil
+	}
+	return removeDupes(s)
+}
+
+func (s Secrets) ToPB() []*controllerapi.Secret {
+	if len(s) == 0 {
+		return nil
+	}
+
+	entries := make([]*controllerapi.Secret, len(s))
+	for i, entry := range s {
+		entries[i] = entry.ToPB()
+	}
+	return entries
+}
+
 type Secret struct {
 	ID       string `json:"id,omitempty"`
 	FilePath string `json:"src,omitempty"`
@@ -85,6 +118,10 @@ func (s *Secret) UnmarshalText(text []byte) error {
 func ParseSecretSpecs(sl []string) ([]*controllerapi.Secret, error) {
 	fs := make([]*controllerapi.Secret, 0, len(sl))
 	for _, v := range sl {
+		if v == "" {
+			continue
+		}
+
 		s, err := parseSecret(v)
 		if err != nil {
 			return nil, err

util/buildflags/secrets_cty.go

@@ -0,0 +1,96 @@
+package buildflags
+
+import (
+	"sync"
+
+	"github.com/zclconf/go-cty/cty"
+	"github.com/zclconf/go-cty/cty/convert"
+)
+
+var secretType = sync.OnceValue(func() cty.Type {
+	return cty.ObjectWithOptionalAttrs(
+		map[string]cty.Type{
+			"id":  cty.String,
+			"src": cty.String,
+			"env": cty.String,
+		},
+		[]string{"id", "src", "env"},
+	)
+})
+
+func (s *Secrets) FromCtyValue(in cty.Value, p cty.Path) error {
+	got := in.Type()
+	if got.IsTupleType() || got.IsListType() {
+		return s.fromCtyValue(in, p)
+	}
+
+	want := cty.List(secretType())
+	return p.NewErrorf("%s", convert.MismatchMessage(got, want))
+}
+
+func (s *Secrets) fromCtyValue(in cty.Value, p cty.Path) error {
+	*s = make([]*Secret, 0, in.LengthInt())
+	for elem := in.ElementIterator(); elem.Next(); {
+		_, value := elem.Element()
+
+		if isEmpty(value) {
+			continue
+		}
+
+		entry := &Secret{}
+		if err := entry.FromCtyValue(value, p); err != nil {
+			return err
+		}
+		*s = append(*s, entry)
+	}
+	return nil
+}
+
+func (s Secrets) ToCtyValue() cty.Value {
+	if len(s) == 0 {
+		return cty.ListValEmpty(secretType())
+	}
+
+	vals := make([]cty.Value, len(s))
+	for i, entry := range s {
+		vals[i] = entry.ToCtyValue()
+	}
+	return cty.ListVal(vals)
+}
+
+func (e *Secret) FromCtyValue(in cty.Value, p cty.Path) error {
+	if in.Type() == cty.String {
+		if err := e.UnmarshalText([]byte(in.AsString())); err != nil {
+			return p.NewError(err)
+		}
+		return nil
+	}
+
+	conv, err := convert.Convert(in, secretType())
+	if err != nil {
+		return err
+	}
+
+	if id := conv.GetAttr("id"); !id.IsNull() {
+		e.ID = id.AsString()
+	}
+	if src := conv.GetAttr("src"); !src.IsNull() {
+		e.FilePath = src.AsString()
+	}
+	if env := conv.GetAttr("env"); !env.IsNull() {
+		e.Env = env.AsString()
+	}
+	return nil
+}
+
+func (e *Secret) ToCtyValue() cty.Value {
+	if e == nil {
+		return cty.NullVal(secretType())
+	}
+
+	return cty.ObjectVal(map[string]cty.Value{
+		"id":  cty.StringVal(e.ID),
+		"src": cty.StringVal(e.FilePath),
+		"env": cty.StringVal(e.Env),
+	})
+}

util/buildflags/ssh.go

@@ -9,6 +9,39 @@ import (
 	"github.com/moby/buildkit/util/gitutil"
 )
 
+type SSHKeys []*SSH
+
+func (s SSHKeys) Merge(other SSHKeys) SSHKeys {
+	if other == nil {
+		s.Normalize()
+		return s
+	} else if s == nil {
+		other.Normalize()
+		return other
+	}
+
+	return append(s, other...).Normalize()
+}
+
+func (s SSHKeys) Normalize() SSHKeys {
+	if len(s) == 0 {
+		return nil
+	}
+	return removeDupes(s)
+}
+
+func (s SSHKeys) ToPB() []*controllerapi.SSH {
+	if len(s) == 0 {
+		return nil
+	}
+
+	entries := make([]*controllerapi.SSH, len(s))
+	for i, entry := range s {
+		entries[i] = entry.ToPB()
+	}
+	return entries
+}
+
 type SSH struct {
 	ID    string   `json:"id,omitempty" cty:"id"`
 	Paths []string `json:"paths,omitempty" cty:"paths"`
@@ -62,6 +95,10 @@ func ParseSSHSpecs(sl []string) ([]*controllerapi.SSH, error) {
 	}
 
 	for _, s := range sl {
+		if s == "" {
+			continue
+		}
+
 		var out SSH
 		if err := out.UnmarshalText([]byte(s)); err != nil {
 			return nil, err

util/buildflags/ssh_cty.go

@@ -0,0 +1,105 @@
+package buildflags
+
+import (
+	"sync"
+
+	"github.com/zclconf/go-cty/cty"
+	"github.com/zclconf/go-cty/cty/convert"
+	"github.com/zclconf/go-cty/cty/gocty"
+)
+
+var sshType = sync.OnceValue(func() cty.Type {
+	return cty.ObjectWithOptionalAttrs(
+		map[string]cty.Type{
+			"id":    cty.String,
+			"paths": cty.List(cty.String),
+		},
+		[]string{"id", "paths"},
+	)
+})
+
+func (s *SSHKeys) FromCtyValue(in cty.Value, p cty.Path) error {
+	got := in.Type()
+	if got.IsTupleType() || got.IsListType() {
+		return s.fromCtyValue(in, p)
+	}
+
+	want := cty.List(sshType())
+	return p.NewErrorf("%s", convert.MismatchMessage(got, want))
+}
+
+func (s *SSHKeys) fromCtyValue(in cty.Value, p cty.Path) error {
+	*s = make([]*SSH, 0, in.LengthInt())
+	for elem := in.ElementIterator(); elem.Next(); {
+		_, value := elem.Element()
+
+		if isEmpty(value) {
+			continue
+		}
+
+		entry := &SSH{}
+		if err := entry.FromCtyValue(value, p); err != nil {
+			return err
+		}
+		*s = append(*s, entry)
+	}
+	return nil
+}
+
+func (s SSHKeys) ToCtyValue() cty.Value {
+	if len(s) == 0 {
+		return cty.ListValEmpty(sshType())
+	}
+
+	vals := make([]cty.Value, len(s))
+	for i, entry := range s {
+		vals[i] = entry.ToCtyValue()
+	}
+	return cty.ListVal(vals)
+}
+
+func (e *SSH) FromCtyValue(in cty.Value, p cty.Path) error {
+	if in.Type() == cty.String {
+		if err := e.UnmarshalText([]byte(in.AsString())); err != nil {
+			return p.NewError(err)
+		}
+		return nil
+	}
+
+	conv, err := convert.Convert(in, sshType())
+	if err != nil {
+		return err
+	}
+
+	if id := conv.GetAttr("id"); !id.IsNull() {
+		e.ID = id.AsString()
+	}
+	if paths := conv.GetAttr("paths"); !paths.IsNull() {
+		if err := gocty.FromCtyValue(paths, &e.Paths); err != nil {
+			return err
+		}
+	}
+	return nil
+}
+
+func (e *SSH) ToCtyValue() cty.Value {
+	if e == nil {
+		return cty.NullVal(sshType())
+	}
+
+	var ctyPaths cty.Value
+	if len(e.Paths) > 0 {
+		paths := make([]cty.Value, len(e.Paths))
+		for i, path := range e.Paths {
+			paths[i] = cty.StringVal(path)
+		}
+		ctyPaths = cty.ListVal(paths)
+	} else {
+		ctyPaths = cty.ListValEmpty(cty.String)
+	}
+
+	return cty.ObjectVal(map[string]cty.Value{
+		"id":    cty.StringVal(e.ID),
+		"paths": ctyPaths,
+	})
+}

util/buildflags/utils.go

@@ -0,0 +1,54 @@
+package buildflags
+
+import (
+	"github.com/zclconf/go-cty/cty"
+	"github.com/zclconf/go-cty/cty/gocty"
+)
+
+type comparable[E any] interface {
+	Equal(other E) bool
+}
+
+func removeDupes[E comparable[E]](s []E) []E {
+	// Move backwards through the slice.
+	// For each element, any elements after the current element are unique.
+	// If we find our current element conflicts with an existing element,
+	// then we swap the offender with the end of the slice and chop it off.
+
+	// Start at the second to last element.
+	// The last element is always unique.
+	for i := len(s) - 2; i >= 0; i-- {
+		elem := s[i]
+		// Check for duplicates after our current element.
+		for j := i + 1; j < len(s); j++ {
+			if elem.Equal(s[j]) {
+				// Found a duplicate, exchange the
+				// duplicate with the last element.
+				s[j], s[len(s)-1] = s[len(s)-1], s[j]
+				s = s[:len(s)-1]
+				break
+			}
+		}
+	}
+	return s
+}
+
+func getAndDelete(m map[string]cty.Value, attr string, gv interface{}) error {
+	if v, ok := m[attr]; ok {
+		delete(m, attr)
+		return gocty.FromCtyValue(v, gv)
+	}
+	return nil
+}
+
+func asMap(m map[string]cty.Value) map[string]string {
+	out := make(map[string]string, len(m))
+	for k, v := range m {
+		out[k] = v.AsString()
+	}
+	return out
+}
+
+func isEmpty(v cty.Value) bool {
+	return v.Type() == cty.String && v.AsString() == ""
+}