buildflags: fix ref only format for command line and bake

Signed-off-by: Jonathan A. Sternberg <jonathan.sternberg@docker.com>

util/buildflags/cache.go

@@ -167,20 +167,37 @@ func (e *CacheOptionsEntry) validate(gv interface{}) error {
 	return nil
 }
 
-func ParseCacheEntry(in []string) ([]*controllerapi.CacheOptionsEntry, error) {
+func ParseCacheEntry(in []string) (CacheOptions, error) {
 	if len(in) == 0 {
 		return nil, nil
 	}
 
 	opts := make(CacheOptions, 0, len(in))
 	for _, in := range in {
+		if !strings.Contains(in, "=") {
+			// This is ref only format. Each field in the CSV is its own entry.
+			fields, err := csvvalue.Fields(in, nil)
+			if err != nil {
+				return nil, err
+			}
+
+			for _, field := range fields {
+				opt := CacheOptionsEntry{}
+				if err := opt.UnmarshalText([]byte(field)); err != nil {
+					return nil, err
+				}
+				opts = append(opts, &opt)
+			}
+			continue
+		}
+
 		var out CacheOptionsEntry
 		if err := out.UnmarshalText([]byte(in)); err != nil {
 			return nil, err
 		}
 		opts = append(opts, &out)
 	}
-	return opts.ToPB(), nil
+	return opts, nil
 }
 
 func addGithubToken(ci *controllerapi.CacheOptionsEntry) {

util/buildflags/cache_cty.go

@@ -30,6 +30,16 @@ func (o *CacheOptions) fromCtyValue(in cty.Value, p cty.Path) error {
 			continue
 		}
 
+		// Special handling for a string type to handle ref only format.
+		if value.Type() == cty.String {
+			entries, err := ParseCacheEntry([]string{value.AsString()})
+			if err != nil {
+				return err
+			}
+			*o = append(*o, entries...)
+			continue
+		}
+
 		entry := &CacheOptionsEntry{}
 		if err := entry.FromCtyValue(value, p); err != nil {
 			return err
@@ -52,13 +62,6 @@ func (o CacheOptions) ToCtyValue() cty.Value {
 }
 
 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

util/buildflags/cache_test.go

@@ -37,7 +37,7 @@ func TestCacheOptions_DerivedVars(t *testing.T) {
 				"session_token":     "not_a_mitm_attack",
 			},
 		},
-	}, cacheFrom)
+	}, cacheFrom.ToPB())
 }
 
 func TestCacheOptions(t *testing.T) {
@@ -109,3 +109,12 @@ func TestCacheOptions(t *testing.T) {
 		require.True(t, result.True())
 	})
 }
+
+func TestCacheOptions_RefOnlyFormat(t *testing.T) {
+	opts, err := ParseCacheEntry([]string{"ref1", "ref2"})
+	require.NoError(t, err)
+	require.Equal(t, CacheOptions{
+		{Type: "registry", Attrs: map[string]string{"ref": "ref1"}},
+		{Type: "registry", Attrs: map[string]string{"ref": "ref2"}},
+	}, opts)
+}