OP#792 initial commit after fork

cmd/warm-backend.go

@@ -0,0 +1,159 @@
+// Copyright (c) 2015-2021 MinIO, Inc.
+//
+// This file is part of MinIO Object Storage stack
+//
+// This program is free software: you can redistribute it and/or modify
+// it under the terms of the GNU Affero General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+//
+// This program is distributed in the hope that it will be useful
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU Affero General Public License for more details.
+//
+// You should have received a copy of the GNU Affero General Public License
+// along with this program.  If not, see <http://www.gnu.org/licenses/>.
+
+package cmd
+
+import (
+	"context"
+	"errors"
+	"fmt"
+	"io"
+	"strings"
+
+	"github.com/minio/madmin-go/v3"
+	xhttp "github.com/minio/minio/internal/http"
+)
+
+// WarmBackendGetOpts is used to express byte ranges within an object. The zero
+// value represents the entire byte range of an object.
+type WarmBackendGetOpts struct {
+	startOffset int64
+	length      int64
+}
+
+// WarmBackend provides interface to be implemented by remote tier backends
+type WarmBackend interface {
+	Put(ctx context.Context, object string, r io.Reader, length int64) (remoteVersionID, error)
+	PutWithMeta(ctx context.Context, object string, r io.Reader, length int64, meta map[string]string) (remoteVersionID, error)
+	Get(ctx context.Context, object string, rv remoteVersionID, opts WarmBackendGetOpts) (io.ReadCloser, error)
+	Remove(ctx context.Context, object string, rv remoteVersionID) error
+	InUse(ctx context.Context) (bool, error)
+}
+
+const probeObject = "probeobject"
+
+// checkWarmBackend checks if tier config credentials have sufficient privileges
+// to perform all operations defined in the WarmBackend interface.
+func checkWarmBackend(ctx context.Context, w WarmBackend) error {
+	remoteVersionID, err := w.Put(ctx, probeObject, strings.NewReader("MinIO"), 5)
+	if err != nil {
+		if _, ok := err.(BackendDown); ok {
+			return err
+		}
+		return tierPermErr{
+			Op:  tierPut,
+			Err: err,
+		}
+	}
+
+	r, err := w.Get(ctx, probeObject, "", WarmBackendGetOpts{})
+	xhttp.DrainBody(r)
+	if err != nil {
+		if _, ok := err.(BackendDown); ok {
+			return err
+		}
+		switch {
+		case isErrBucketNotFound(err):
+			return errTierBucketNotFound
+		case isErrSignatureDoesNotMatch(err):
+			return errTierInvalidCredentials
+		default:
+			return tierPermErr{
+				Op:  tierGet,
+				Err: err,
+			}
+		}
+	}
+	if err = w.Remove(ctx, probeObject, remoteVersionID); err != nil {
+		if _, ok := err.(BackendDown); ok {
+			return err
+		}
+		return tierPermErr{
+			Op:  tierDelete,
+			Err: err,
+		}
+	}
+	return err
+}
+
+type tierOp uint8
+
+const (
+	_ tierOp = iota
+	tierGet
+	tierPut
+	tierDelete
+)
+
+func (op tierOp) String() string {
+	switch op {
+	case tierGet:
+		return "GET"
+	case tierPut:
+		return "PUT"
+	case tierDelete:
+		return "DELETE"
+	}
+	return "UNKNOWN"
+}
+
+type tierPermErr struct {
+	Op  tierOp
+	Err error
+}
+
+func (te tierPermErr) Error() string {
+	return fmt.Sprintf("failed to perform %s: %v", te.Op, te.Err)
+}
+
+func errIsTierPermError(err error) bool {
+	var tpErr tierPermErr
+	return errors.As(err, &tpErr)
+}
+
+// remoteVersionID represents the version id of an object in the remote tier.
+// Its usage is remote tier cloud implementation specific.
+type remoteVersionID string
+
+// newWarmBackend instantiates the tier type specific WarmBackend, runs
+// checkWarmBackend on it.
+func newWarmBackend(ctx context.Context, tier madmin.TierConfig, probe bool) (d WarmBackend, err error) {
+	switch tier.Type {
+	case madmin.S3:
+		d, err = newWarmBackendS3(*tier.S3, tier.Name)
+	case madmin.Azure:
+		d, err = newWarmBackendAzure(*tier.Azure, tier.Name)
+	case madmin.GCS:
+		d, err = newWarmBackendGCS(*tier.GCS, tier.Name)
+	case madmin.MinIO:
+		d, err = newWarmBackendMinIO(*tier.MinIO, tier.Name)
+	default:
+		return nil, errTierTypeUnsupported
+	}
+	if err != nil {
+		tierLogIf(ctx, err)
+		return nil, errTierInvalidConfig
+	}
+
+	if probe {
+		if err = checkWarmBackend(ctx, d); err != nil {
+			return nil, err
+		}
+	}
+
+	return d, nil
+}