diff --git a/cmd/release_config/crunch_flags/main.go b/cmd/release_config/crunch_flags/main.go
index 29290a4..5b64062 100644
--- a/cmd/release_config/crunch_flags/main.go
+++ b/cmd/release_config/crunch_flags/main.go
@@ -102,10 +102,13 @@
 			description = ""
 			continue
 		}
-		declValue := matches[declRegexp.SubexpIndex("value")]
 		declName := matches[declRegexp.SubexpIndex("name")]
-		container := rc_proto.Container(rc_proto.Container_value[matches[declRegexp.SubexpIndex("container")]])
+		declValue := matches[declRegexp.SubexpIndex("value")]
 		description = strings.TrimSpace(description)
+		containers := []string{strings.ToLower(matches[declRegexp.SubexpIndex("container")])}
+		if containers[0] == "all" {
+			containers = []string{"product", "system", "system_ext", "vendor"}
+		}
 		var namespace string
 		var ok bool
 		if namespace, ok = namespaceMap[declName]; !ok {
@@ -115,7 +118,7 @@
 			Name:        proto.String(declName),
 			Namespace:   proto.String(namespace),
 			Description: proto.String(description),
-			Container:   &container,
+			Containers:  containers,
 		}
 		description = ""
 		// Most build flags are `workflow: PREBUILT`.
@@ -213,6 +216,12 @@
 	return err
 }
 
+var (
+	allContainers = func() []string {
+		return []string{"product", "system", "system_ext", "vendor"}
+	}()
+)
+
 func ProcessReleaseConfigMap(dir string, descriptionMap map[string]string) error {
 	path := filepath.Join(dir, "release_config_map.mk")
 	if _, err := os.Stat(path); err != nil {
@@ -235,16 +244,16 @@
 		return err
 	}
 	cleanDir := strings.TrimLeft(dir, "../")
-	var defaultContainer rc_proto.Container
+	var defaultContainers []string
 	switch {
 	case strings.HasPrefix(cleanDir, "build/") || cleanDir == "vendor/google_shared/build":
-		defaultContainer = rc_proto.Container(rc_proto.Container_ALL)
+		defaultContainers = allContainers
 	case cleanDir == "vendor/google/release":
-		defaultContainer = rc_proto.Container(rc_proto.Container_ALL)
+		defaultContainers = allContainers
 	default:
-		defaultContainer = rc_proto.Container(rc_proto.Container_VENDOR)
+		defaultContainers = []string{"vendor"}
 	}
-	releaseConfigMap := &rc_proto.ReleaseConfigMap{DefaultContainer: &defaultContainer}
+	releaseConfigMap := &rc_proto.ReleaseConfigMap{DefaultContainers: defaultContainers}
 	// If we find a description for the directory, include it.
 	if description, ok := descriptionMap[cleanDir]; ok {
 		releaseConfigMap.Description = proto.String(description)
diff --git a/cmd/release_config/release_config_lib/release_config.go b/cmd/release_config/release_config_lib/release_config.go
index a7a05ae..5996c46 100644
--- a/cmd/release_config/release_config_lib/release_config.go
+++ b/cmd/release_config/release_config_lib/release_config.go
@@ -109,23 +109,17 @@
 	config.FlagArtifacts = configs.FlagArtifacts.Clone()
 	// Add RELEASE_ACONFIG_VALUE_SETS
 	workflowManual := rc_proto.Workflow(rc_proto.Workflow_MANUAL)
-	container := rc_proto.Container(rc_proto.Container_ALL)
 	releaseAconfigValueSets := FlagArtifact{
 		FlagDeclaration: &rc_proto.FlagDeclaration{
 			Name:        proto.String("RELEASE_ACONFIG_VALUE_SETS"),
 			Namespace:   proto.String("android_UNKNOWN"),
 			Description: proto.String("Aconfig value sets assembled by release-config"),
 			Workflow:    &workflowManual,
-			Container:   &container,
-			Value:       &rc_proto.Value{Val: &rc_proto.Value_StringValue{""}},
+			Containers:  []string{"system", "system_ext", "product", "vendor"},
+			Value:       &rc_proto.Value{Val: &rc_proto.Value_UnspecifiedValue{false}},
 		},
 		DeclarationIndex: -1,
-		Traces: []*rc_proto.Tracepoint{
-			&rc_proto.Tracepoint{
-				Source: proto.String("$release-config"),
-				Value:  &rc_proto.Value{Val: &rc_proto.Value_StringValue{""}},
-			},
-		},
+		Traces:           []*rc_proto.Tracepoint{},
 	}
 	config.FlagArtifacts["RELEASE_ACONFIG_VALUE_SETS"] = &releaseAconfigValueSets
 
@@ -163,22 +157,22 @@
 	}
 	myDirsMap := make(map[int]bool)
 	for _, contrib := range contributionsToApply {
-		if len(contrib.proto.AconfigValueSets) > 0 {
-			contribAconfigValueSets := []string{}
-			for _, v := range contrib.proto.AconfigValueSets {
-				if _, ok := myAconfigValueSetsMap[v]; !ok {
-					contribAconfigValueSets = append(contribAconfigValueSets, v)
-					myAconfigValueSetsMap[v] = true
-				}
+		contribAconfigValueSets := []string{}
+		// Gather the aconfig_value_sets from this contribution that are not already in the list.
+		for _, v := range contrib.proto.AconfigValueSets {
+			if _, ok := myAconfigValueSetsMap[v]; !ok {
+				contribAconfigValueSets = append(contribAconfigValueSets, v)
+				myAconfigValueSetsMap[v] = true
 			}
-			myAconfigValueSets = append(myAconfigValueSets, contribAconfigValueSets...)
-			releaseAconfigValueSets.Traces = append(
-				releaseAconfigValueSets.Traces,
-				&rc_proto.Tracepoint{
-					Source: proto.String(contrib.path),
-					Value:  &rc_proto.Value{Val: &rc_proto.Value_StringValue{strings.Join(contribAconfigValueSets, " ")}},
-				})
 		}
+		myAconfigValueSets = append(myAconfigValueSets, contribAconfigValueSets...)
+		releaseAconfigValueSets.Traces = append(
+			releaseAconfigValueSets.Traces,
+			&rc_proto.Tracepoint{
+				Source: proto.String(contrib.path),
+				Value:  &rc_proto.Value{Val: &rc_proto.Value_StringValue{strings.Join(contribAconfigValueSets, " ")}},
+			})
+
 		myDirsMap[contrib.DeclarationIndex] = true
 		for _, value := range contrib.FlagValues {
 			name := *value.proto.Name
@@ -214,30 +208,16 @@
 
 	// Now build the per-partition artifacts
 	config.PartitionBuildFlags = make(map[string]*rc_proto.FlagArtifacts)
-	addPartitionArtifact := func(container string, artifact *rc_proto.FlagArtifact) {
-		if _, ok := config.PartitionBuildFlags[container]; !ok {
-			config.PartitionBuildFlags[container] = &rc_proto.FlagArtifacts{}
-		}
-		config.PartitionBuildFlags[container].FlagArtifacts = append(config.PartitionBuildFlags[container].FlagArtifacts, artifact)
-	}
 	for _, v := range config.FlagArtifacts {
-		container := strings.ToLower(rc_proto.Container_name[int32(v.FlagDeclaration.GetContainer())])
 		artifact, err := v.MarshalWithoutTraces()
 		if err != nil {
 			return err
 		}
-		switch container {
-		case "all":
-			for cVal, cName := range rc_proto.Container_name {
-				// Skip unspecified, and "ALL", but place the flag in the rest.
-				if cVal == 0 || cName == "ALL" {
-					continue
-				}
-				cName = strings.ToLower(cName)
-				addPartitionArtifact(cName, artifact)
+		for _, container := range v.FlagDeclaration.Containers {
+			if _, ok := config.PartitionBuildFlags[container]; !ok {
+				config.PartitionBuildFlags[container] = &rc_proto.FlagArtifacts{}
 			}
-		default:
-			addPartitionArtifact(container, artifact)
+			config.PartitionBuildFlags[container].FlagArtifacts = append(config.PartitionBuildFlags[container].FlagArtifacts, artifact)
 		}
 	}
 	config.ReleaseConfigArtifact = &rc_proto.ReleaseConfigArtifact{
diff --git a/cmd/release_config/release_config_lib/release_configs.go b/cmd/release_config/release_config_lib/release_configs.go
index 3204b18..d7d4a8c 100644
--- a/cmd/release_config/release_config_lib/release_configs.go
+++ b/cmd/release_config/release_config_lib/release_configs.go
@@ -118,9 +118,14 @@
 
 func (configs *ReleaseConfigs) LoadReleaseConfigMap(path string, ConfigDirIndex int) error {
 	m := ReleaseConfigMapFactory(path)
-	if m.proto.DefaultContainer == nil {
+	if m.proto.DefaultContainers == nil {
 		return fmt.Errorf("Release config map %s lacks default_container", path)
 	}
+	for _, container := range m.proto.DefaultContainers {
+		if !validContainer(container) {
+			return fmt.Errorf("Release config map %s has invalid container %s", path, container)
+		}
+	}
 	dir := filepath.Dir(path)
 	// Record any aliases, checking for duplicates.
 	for _, alias := range m.proto.Aliases {
@@ -138,9 +143,16 @@
 	err = WalkTextprotoFiles(dir, "flag_declarations", func(path string, d fs.DirEntry, err error) error {
 		flagDeclaration := FlagDeclarationFactory(path)
 		// Container must be specified.
-		if flagDeclaration.Container == nil {
-			flagDeclaration.Container = m.proto.DefaultContainer
+		if flagDeclaration.Containers == nil {
+			flagDeclaration.Containers = m.proto.DefaultContainers
+		} else {
+			for _, container := range flagDeclaration.Containers {
+				if !validContainer(container) {
+					return fmt.Errorf("Flag declaration %s has invalid container %s", path, container)
+				}
+			}
 		}
+
 		// TODO: once we have namespaces initialized, we can throw an error here.
 		if flagDeclaration.Namespace == nil {
 			flagDeclaration.Namespace = proto.String("android_UNKNOWN")
@@ -253,19 +265,12 @@
 		flag := myFlagArtifacts[name]
 		decl := flag.FlagDeclaration
 
-		// cName := strings.ToLower(rc_proto.Container_name[decl.GetContainer()])
-		cName := strings.ToLower(decl.Container.String())
-		if cName == strings.ToLower(rc_proto.Container_ALL.String()) {
-			partitions["product"] = append(partitions["product"], name)
-			partitions["system"] = append(partitions["system"], name)
-			partitions["system_ext"] = append(partitions["system_ext"], name)
-			partitions["vendor"] = append(partitions["vendor"], name)
-		} else {
-			partitions[cName] = append(partitions[cName], name)
+		for _, container := range decl.Containers {
+			partitions[container] = append(partitions[container], name)
 		}
 		value := MarshalValue(flag.Value)
 		makeVars[name] = value
-		addVar(name, "PARTITIONS", cName)
+		addVar(name, "PARTITIONS", strings.Join(decl.Containers, " "))
 		addVar(name, "DEFAULT", MarshalValue(decl.Value))
 		addVar(name, "VALUE", value)
 		addVar(name, "DECLARED_IN", *flag.Traces[0].Source)
diff --git a/cmd/release_config/release_config_lib/util.go b/cmd/release_config/release_config_lib/util.go
index 86940da..d55cf29 100644
--- a/cmd/release_config/release_config_lib/util.go
+++ b/cmd/release_config/release_config_lib/util.go
@@ -20,13 +20,17 @@
 	"io/fs"
 	"os"
 	"path/filepath"
+	"regexp"
 	"strings"
 
 	"google.golang.org/protobuf/encoding/prototext"
 	"google.golang.org/protobuf/proto"
 )
 
-var disableWarnings bool
+var (
+	disableWarnings    bool
+	containerRegexp, _ = regexp.Compile("^[a-z][a-z0-9]*([._][a-z][a-z0-9]*)*$")
+)
 
 type StringList []string
 
@@ -128,6 +132,10 @@
 	return 0, nil
 }
 
+func validContainer(container string) bool {
+	return containerRegexp.MatchString(container)
+}
+
 // Returns the default value for release config artifacts.
 func GetDefaultOutDir() string {
 	outEnv := os.Getenv("OUT_DIR")
diff --git a/cmd/release_config/release_config_proto/build_flags_src.pb.go b/cmd/release_config/release_config_proto/build_flags_src.pb.go
index ca2005c..8054bd9 100644
--- a/cmd/release_config/release_config_proto/build_flags_src.pb.go
+++ b/cmd/release_config/release_config_proto/build_flags_src.pb.go
@@ -98,76 +98,6 @@
 	return file_build_flags_src_proto_rawDescGZIP(), []int{0}
 }
 
-type Container int32
-
-const (
-	Container_UNSPECIFIED_container Container = 0
-	// All containers
-	Container_ALL Container = 1
-	// Specific containers
-	Container_PRODUCT    Container = 2
-	Container_SYSTEM     Container = 3
-	Container_SYSTEM_EXT Container = 4
-	Container_VENDOR     Container = 5
-)
-
-// Enum value maps for Container.
-var (
-	Container_name = map[int32]string{
-		0: "UNSPECIFIED_container",
-		1: "ALL",
-		2: "PRODUCT",
-		3: "SYSTEM",
-		4: "SYSTEM_EXT",
-		5: "VENDOR",
-	}
-	Container_value = map[string]int32{
-		"UNSPECIFIED_container": 0,
-		"ALL":                   1,
-		"PRODUCT":               2,
-		"SYSTEM":                3,
-		"SYSTEM_EXT":            4,
-		"VENDOR":                5,
-	}
-)
-
-func (x Container) Enum() *Container {
-	p := new(Container)
-	*p = x
-	return p
-}
-
-func (x Container) String() string {
-	return protoimpl.X.EnumStringOf(x.Descriptor(), protoreflect.EnumNumber(x))
-}
-
-func (Container) Descriptor() protoreflect.EnumDescriptor {
-	return file_build_flags_src_proto_enumTypes[1].Descriptor()
-}
-
-func (Container) Type() protoreflect.EnumType {
-	return &file_build_flags_src_proto_enumTypes[1]
-}
-
-func (x Container) Number() protoreflect.EnumNumber {
-	return protoreflect.EnumNumber(x)
-}
-
-// Deprecated: Do not use.
-func (x *Container) UnmarshalJSON(b []byte) error {
-	num, err := protoimpl.X.UnmarshalJSONEnum(x.Descriptor(), b)
-	if err != nil {
-		return err
-	}
-	*x = Container(num)
-	return nil
-}
-
-// Deprecated: Use Container.Descriptor instead.
-func (Container) EnumDescriptor() ([]byte, []int) {
-	return file_build_flags_src_proto_rawDescGZIP(), []int{1}
-}
-
 type Value struct {
 	state         protoimpl.MessageState
 	sizeCache     protoimpl.SizeCache
@@ -298,7 +228,7 @@
 	Workflow *Workflow `protobuf:"varint,205,opt,name=workflow,enum=android.release_config_proto.Workflow" json:"workflow,omitempty"`
 	// The container for this flag.  This overrides any default container given
 	// in the release_config_map message.
-	Container *Container `protobuf:"varint,206,opt,name=container,enum=android.release_config_proto.Container" json:"container,omitempty"`
+	Containers []string `protobuf:"bytes,206,rep,name=containers" json:"containers,omitempty"`
 }
 
 func (x *FlagDeclaration) Reset() {
@@ -368,11 +298,11 @@
 	return Workflow_UNSPECIFIED_workflow
 }
 
-func (x *FlagDeclaration) GetContainer() Container {
-	if x != nil && x.Container != nil {
-		return *x.Container
+func (x *FlagDeclaration) GetContainers() []string {
+	if x != nil {
+		return x.Containers
 	}
-	return Container_UNSPECIFIED_container
+	return nil
 }
 
 type FlagValue struct {
@@ -581,7 +511,7 @@
 	// Description of this map and its intended use.
 	Description *string `protobuf:"bytes,2,opt,name=description" json:"description,omitempty"`
 	// The default container for flags declared here.
-	DefaultContainer *Container `protobuf:"varint,3,opt,name=default_container,json=defaultContainer,enum=android.release_config_proto.Container" json:"default_container,omitempty"`
+	DefaultContainers []string `protobuf:"bytes,3,rep,name=default_containers,json=defaultContainers" json:"default_containers,omitempty"`
 }
 
 func (x *ReleaseConfigMap) Reset() {
@@ -630,11 +560,11 @@
 	return ""
 }
 
-func (x *ReleaseConfigMap) GetDefaultContainer() Container {
-	if x != nil && x.DefaultContainer != nil {
-		return *x.DefaultContainer
+func (x *ReleaseConfigMap) GetDefaultContainers() []string {
+	if x != nil {
+		return x.DefaultContainers
 	}
-	return Container_UNSPECIFIED_container
+	return nil
 }
 
 var File_build_flags_src_proto protoreflect.FileDescriptor
@@ -653,7 +583,7 @@
 	0x6c, 0x75, 0x65, 0x18, 0xca, 0x01, 0x20, 0x01, 0x28, 0x08, 0x48, 0x00, 0x52, 0x09, 0x62, 0x6f,
 	0x6f, 0x6c, 0x56, 0x61, 0x6c, 0x75, 0x65, 0x12, 0x1d, 0x0a, 0x08, 0x6f, 0x62, 0x73, 0x6f, 0x6c,
 	0x65, 0x74, 0x65, 0x18, 0xcb, 0x01, 0x20, 0x01, 0x28, 0x08, 0x48, 0x00, 0x52, 0x08, 0x6f, 0x62,
-	0x73, 0x6f, 0x6c, 0x65, 0x74, 0x65, 0x42, 0x05, 0x0a, 0x03, 0x76, 0x61, 0x6c, 0x22, 0xbd, 0x02,
+	0x73, 0x6f, 0x6c, 0x65, 0x74, 0x65, 0x42, 0x05, 0x0a, 0x03, 0x76, 0x61, 0x6c, 0x22, 0x96, 0x02,
 	0x0a, 0x10, 0x66, 0x6c, 0x61, 0x67, 0x5f, 0x64, 0x65, 0x63, 0x6c, 0x61, 0x72, 0x61, 0x74, 0x69,
 	0x6f, 0x6e, 0x12, 0x12, 0x0a, 0x04, 0x6e, 0x61, 0x6d, 0x65, 0x18, 0x01, 0x20, 0x01, 0x28, 0x09,
 	0x52, 0x04, 0x6e, 0x61, 0x6d, 0x65, 0x12, 0x1c, 0x0a, 0x09, 0x6e, 0x61, 0x6d, 0x65, 0x73, 0x70,
@@ -668,59 +598,47 @@
 	0x01, 0x20, 0x01, 0x28, 0x0e, 0x32, 0x26, 0x2e, 0x61, 0x6e, 0x64, 0x72, 0x6f, 0x69, 0x64, 0x2e,
 	0x72, 0x65, 0x6c, 0x65, 0x61, 0x73, 0x65, 0x5f, 0x63, 0x6f, 0x6e, 0x66, 0x69, 0x67, 0x5f, 0x70,
 	0x72, 0x6f, 0x74, 0x6f, 0x2e, 0x77, 0x6f, 0x72, 0x6b, 0x66, 0x6c, 0x6f, 0x77, 0x52, 0x08, 0x77,
-	0x6f, 0x72, 0x6b, 0x66, 0x6c, 0x6f, 0x77, 0x12, 0x46, 0x0a, 0x09, 0x63, 0x6f, 0x6e, 0x74, 0x61,
-	0x69, 0x6e, 0x65, 0x72, 0x18, 0xce, 0x01, 0x20, 0x01, 0x28, 0x0e, 0x32, 0x27, 0x2e, 0x61, 0x6e,
-	0x64, 0x72, 0x6f, 0x69, 0x64, 0x2e, 0x72, 0x65, 0x6c, 0x65, 0x61, 0x73, 0x65, 0x5f, 0x63, 0x6f,
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+	0x72, 0x6f, 0x69, 0x64, 0x2f, 0x73, 0x6f, 0x6f, 0x6e, 0x67, 0x2f, 0x72, 0x65, 0x6c, 0x65, 0x61,
+	0x73, 0x65, 0x5f, 0x63, 0x6f, 0x6e, 0x66, 0x69, 0x67, 0x2f, 0x72, 0x65, 0x6c, 0x65, 0x61, 0x73,
+	0x65, 0x5f, 0x63, 0x6f, 0x6e, 0x66, 0x69, 0x67, 0x5f, 0x70, 0x72, 0x6f, 0x74, 0x6f,
 }
 
 var (
@@ -735,30 +653,27 @@
 	return file_build_flags_src_proto_rawDescData
 }
 
-var file_build_flags_src_proto_enumTypes = make([]protoimpl.EnumInfo, 2)
+var file_build_flags_src_proto_enumTypes = make([]protoimpl.EnumInfo, 1)
 var file_build_flags_src_proto_msgTypes = make([]protoimpl.MessageInfo, 6)
 var file_build_flags_src_proto_goTypes = []interface{}{
 	(Workflow)(0),            // 0: android.release_config_proto.workflow
-	(Container)(0),           // 1: android.release_config_proto.container
-	(*Value)(nil),            // 2: android.release_config_proto.value
-	(*FlagDeclaration)(nil),  // 3: android.release_config_proto.flag_declaration
-	(*FlagValue)(nil),        // 4: android.release_config_proto.flag_value
-	(*ReleaseConfig)(nil),    // 5: android.release_config_proto.release_config
-	(*ReleaseAlias)(nil),     // 6: android.release_config_proto.release_alias
-	(*ReleaseConfigMap)(nil), // 7: android.release_config_proto.release_config_map
+	(*Value)(nil),            // 1: android.release_config_proto.value
+	(*FlagDeclaration)(nil),  // 2: android.release_config_proto.flag_declaration
+	(*FlagValue)(nil),        // 3: android.release_config_proto.flag_value
+	(*ReleaseConfig)(nil),    // 4: android.release_config_proto.release_config
+	(*ReleaseAlias)(nil),     // 5: android.release_config_proto.release_alias
+	(*ReleaseConfigMap)(nil), // 6: android.release_config_proto.release_config_map
 }
 var file_build_flags_src_proto_depIdxs = []int32{
-	2, // 0: android.release_config_proto.flag_declaration.value:type_name -> android.release_config_proto.value
+	1, // 0: android.release_config_proto.flag_declaration.value:type_name -> android.release_config_proto.value
 	0, // 1: android.release_config_proto.flag_declaration.workflow:type_name -> android.release_config_proto.workflow
-	1, // 2: android.release_config_proto.flag_declaration.container:type_name -> android.release_config_proto.container
-	2, // 3: android.release_config_proto.flag_value.value:type_name -> android.release_config_proto.value
-	6, // 4: android.release_config_proto.release_config_map.aliases:type_name -> android.release_config_proto.release_alias
-	1, // 5: android.release_config_proto.release_config_map.default_container:type_name -> android.release_config_proto.container
-	6, // [6:6] is the sub-list for method output_type
-	6, // [6:6] is the sub-list for method input_type
-	6, // [6:6] is the sub-list for extension type_name
-	6, // [6:6] is the sub-list for extension extendee
-	0, // [0:6] is the sub-list for field type_name
+	1, // 2: android.release_config_proto.flag_value.value:type_name -> android.release_config_proto.value
+	5, // 3: android.release_config_proto.release_config_map.aliases:type_name -> android.release_config_proto.release_alias
+	4, // [4:4] is the sub-list for method output_type
+	4, // [4:4] is the sub-list for method input_type
+	4, // [4:4] is the sub-list for extension type_name
+	4, // [4:4] is the sub-list for extension extendee
+	0, // [0:4] is the sub-list for field type_name
 }
 
 func init() { file_build_flags_src_proto_init() }
@@ -851,7 +766,7 @@
 		File: protoimpl.DescBuilder{
 			GoPackagePath: reflect.TypeOf(x{}).PkgPath(),
 			RawDescriptor: file_build_flags_src_proto_rawDesc,
-			NumEnums:      2,
+			NumEnums:      1,
 			NumMessages:   6,
 			NumExtensions: 0,
 			NumServices:   0,
diff --git a/cmd/release_config/release_config_proto/build_flags_src.proto b/cmd/release_config/release_config_proto/build_flags_src.proto
index 92edc2a..017e5d4 100644
--- a/cmd/release_config/release_config_proto/build_flags_src.proto
+++ b/cmd/release_config/release_config_proto/build_flags_src.proto
@@ -53,19 +53,6 @@
   MANUAL = 3;
 }
 
-enum container {
-  UNSPECIFIED_container = 0;
-
-  // All containers
-  ALL = 1;
-
-  // Specific containers
-  PRODUCT = 2;
-  SYSTEM = 3;
-  SYSTEM_EXT = 4;
-  VENDOR = 5;
-}
-
 message value {
   oneof val {
     bool unspecified_value = 200;
@@ -100,7 +87,7 @@
 
   // The container for this flag.  This overrides any default container given
   // in the release_config_map message.
-  optional container container = 206;
+  repeated string containers = 206;
 
   // The package associated with this flag.
   // (when Gantry is ready for it) optional string package = 207;
@@ -152,7 +139,7 @@
   optional string description = 2;
 
   // The default container for flags declared here.
-  optional container default_container = 3;
+  repeated string default_containers = 3;
 
   // If needed, we can add these fields instead of hardcoding the location.
   // Flag declarations: `flag_declarations/*.textproto`