Store bucket created time as a metadata (#9465)

Fixes #9459

cmd/bucket-meta.go

@@ -0,0 +1,165 @@
+/*
+ * MinIO Cloud Storage, (C) 2020 MinIO, Inc.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package cmd
+
+import (
+	"context"
+	"encoding/binary"
+	"errors"
+	"fmt"
+	"path"
+	"time"
+
+	"github.com/minio/minio/cmd/logger"
+)
+
+const (
+	legacyBucketObjectLockEnabledConfigFile = "object-lock-enabled.json"
+	legacyBucketObjectLockEnabledConfig     = `{"x-amz-bucket-object-lock-enabled":true}`
+
+	bucketMetadataFile    = ".metadata.bin"
+	bucketMetadataFormat  = 1
+	bucketMetadataVersion = 1
+)
+
+//go:generate msgp -file $GOFILE -unexported
+
+// bucketMetadata contains bucket metadata.
+// When adding/removing fields, regenerate the marshal code using the go generate above.
+// Only changing meaning of fields requires a version bump.
+// bucketMetadataFormat refers to the format.
+// bucketMetadataVersion can be used to track a rolling upgrade of a field.
+type bucketMetadata struct {
+	Name        string
+	Created     time.Time
+	LockEnabled bool
+}
+
+// newBucketMetadata creates bucketMetadata with the supplied name and Created to Now.
+func newBucketMetadata(name string) bucketMetadata {
+	return bucketMetadata{
+		Name:    name,
+		Created: UTCNow(),
+	}
+}
+
+// loadBucketMeta loads the metadata of bucket by name from ObjectLayer o.
+// If an error is returned the returned metadata will be default initialized.
+func loadBucketMeta(ctx context.Context, o ObjectLayer, name string) (bucketMetadata, error) {
+	b := newBucketMetadata(name)
+	configFile := path.Join(bucketConfigPrefix, name, bucketMetadataFile)
+	data, err := readConfig(ctx, o, configFile)
+	if err != nil {
+		return b, err
+	}
+	if len(data) <= 4 {
+		return b, fmt.Errorf("loadBucketMetadata: no data")
+	}
+	// Read header
+	switch binary.LittleEndian.Uint16(data[0:2]) {
+	case bucketMetadataFormat:
+	default:
+		return b, fmt.Errorf("loadBucketMetadata: unknown format: %d", binary.LittleEndian.Uint16(data[0:2]))
+	}
+	switch binary.LittleEndian.Uint16(data[2:4]) {
+	case bucketMetadataVersion:
+	default:
+		return b, fmt.Errorf("loadBucketMetadata: unknown version: %d", binary.LittleEndian.Uint16(data[2:4]))
+	}
+
+	// OK, parse data.
+	_, err = b.UnmarshalMsg(data[4:])
+	return b, err
+}
+
+var errMetaDataConverted = errors.New("metadata converted")
+
+// loadBucketMetadata loads and migrates to bucket metadata.
+func loadBucketMetadata(ctx context.Context, objectAPI ObjectLayer, bucket string) (bucketMetadata, error) {
+	meta, err := loadBucketMeta(ctx, objectAPI, bucket)
+	if err == nil {
+		return meta, nil
+	}
+
+	if err != errConfigNotFound {
+		return meta, err
+	}
+
+	// Control here means old bucket without bucket metadata. Hence we migrate existing settings.
+	if err = meta.convertLegacyLockconfig(ctx, objectAPI); err != nil {
+		return meta, err
+	}
+
+	return meta, errMetaDataConverted
+}
+
+func (b *bucketMetadata) convertLegacyLockconfig(ctx context.Context, objectAPI ObjectLayer) error {
+	configFile := path.Join(bucketConfigPrefix, b.Name, legacyBucketObjectLockEnabledConfigFile)
+
+	save := func() error {
+		if err := b.save(ctx, objectAPI); err != nil {
+			return err
+		}
+
+		logger.LogIf(ctx, deleteConfig(ctx, objectAPI, configFile))
+		return nil
+	}
+
+	configData, err := readConfig(ctx, objectAPI, configFile)
+	if err != nil {
+		if err != errConfigNotFound {
+			return err
+		}
+
+		return save()
+	}
+
+	if string(configData) != legacyBucketObjectLockEnabledConfig {
+		return fmt.Errorf("content mismatch in config file %v", configFile)
+	}
+
+	b.LockEnabled = true
+	return save()
+}
+
+// save config to supplied ObjectLayer o.
+func (b *bucketMetadata) save(ctx context.Context, o ObjectLayer) error {
+	data := make([]byte, 4, b.Msgsize()+4)
+	// Put header
+	binary.LittleEndian.PutUint16(data[0:2], bucketMetadataFormat)
+	binary.LittleEndian.PutUint16(data[2:4], bucketMetadataVersion)
+
+	// Add data
+	data, err := b.MarshalMsg(data)
+	if err != nil {
+		return err
+	}
+	configFile := path.Join(bucketConfigPrefix, b.Name, bucketMetadataFile)
+	return saveConfig(ctx, o, configFile, data)
+}
+
+// delete the config metadata.
+// If config does not exist no error is returned.
+func (b bucketMetadata) delete(ctx context.Context, o ObjectLayer) error {
+	configFile := path.Join(bucketConfigPrefix, b.Name, bucketMetadataFile)
+	err := deleteConfig(ctx, o, configFile)
+	if err == errConfigNotFound {
+		// We don't care
+		err = nil
+	}
+	return err
+}