etcdctl: add etcdctl snapshot pipe command

To improve the security of etcdctl. Added the ability to write snapshots to stdout without writing data to disk.

Signed-off-by: Ais8Ooz8 <[email protected]>

client/v3/snapshot/v3_snapshot.go

@@ -97,7 +97,11 @@ func SaveWithVersion(ctx context.Context, lg *zap.Logger, cfg clientv3.Config, d
 	defer os.RemoveAll(partPath)
 	defer f.Close()
 
-	version, _ := WriteSnapshotWithVersion(ctx, lg, cfg, f)
+	var version string
+	version, err = WriteSnapshotWithVersion(ctx, lg, cfg, f)
+	if err != nil {
+		return version, err
+	}
 	if err = os.Rename(partPath, dbPath); err != nil {
 		return version, fmt.Errorf("could not rename %s to %s (%v)", partPath, dbPath, err)
 	}