OP#792 initial commit after fork

cmd/etcd.go

@@ -0,0 +1,91 @@
+// 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"
+
+	etcd "go.etcd.io/etcd/client/v3"
+)
+
+var errEtcdUnreachable = errors.New("etcd is unreachable, please check your endpoints")
+
+func etcdErrToErr(err error, etcdEndpoints []string) error {
+	if err == nil {
+		return nil
+	}
+	switch err {
+	case context.DeadlineExceeded:
+		return fmt.Errorf("%w %s", errEtcdUnreachable, etcdEndpoints)
+	default:
+		return fmt.Errorf("unexpected error %w from etcd, please check your endpoints %s", err, etcdEndpoints)
+	}
+}
+
+func saveKeyEtcdWithTTL(ctx context.Context, client *etcd.Client, key string, data []byte, ttl int64) error {
+	timeoutCtx, cancel := context.WithTimeout(ctx, defaultContextTimeout)
+	defer cancel()
+	lease, err := client.Grant(timeoutCtx, ttl)
+	if err != nil {
+		return etcdErrToErr(err, client.Endpoints())
+	}
+	_, err = client.Put(timeoutCtx, key, string(data), etcd.WithLease(lease.ID))
+	etcdLogIf(ctx, err)
+	return etcdErrToErr(err, client.Endpoints())
+}
+
+func saveKeyEtcd(ctx context.Context, client *etcd.Client, key string, data []byte, opts ...options) error {
+	timeoutCtx, cancel := context.WithTimeout(ctx, defaultContextTimeout)
+	defer cancel()
+	if len(opts) > 0 {
+		return saveKeyEtcdWithTTL(ctx, client, key, data, opts[0].ttl)
+	}
+	_, err := client.Put(timeoutCtx, key, string(data))
+	etcdLogIf(ctx, err)
+	return etcdErrToErr(err, client.Endpoints())
+}
+
+func deleteKeyEtcd(ctx context.Context, client *etcd.Client, key string) error {
+	timeoutCtx, cancel := context.WithTimeout(ctx, defaultContextTimeout)
+	defer cancel()
+
+	_, err := client.Delete(timeoutCtx, key)
+	etcdLogIf(ctx, err)
+	return etcdErrToErr(err, client.Endpoints())
+}
+
+func readKeyEtcd(ctx context.Context, client *etcd.Client, key string) ([]byte, error) {
+	timeoutCtx, cancel := context.WithTimeout(ctx, defaultContextTimeout)
+	defer cancel()
+	resp, err := client.Get(timeoutCtx, key)
+	if err != nil {
+		etcdLogOnceIf(ctx, err, "etcd-retrieve-keys")
+		return nil, etcdErrToErr(err, client.Endpoints())
+	}
+	if resp.Count == 0 {
+		return nil, errConfigNotFound
+	}
+	for _, ev := range resp.Kvs {
+		if string(ev.Key) == key {
+			return ev.Value, nil
+		}
+	}
+	return nil, errConfigNotFound
+}