core: allow RO mode for Bolt and Level

docs/node-configuration.md

@@ -47,14 +47,20 @@ DBConfiguration:
   Type: leveldb
   LevelDBOptions:
     DataDirectoryPath: /chains/privnet
+    ReadOnly: false
   BoltDBOptions:
     FilePath: ./chains/privnet.bolt
+    ReadOnly: false
 ```
 where:
 - `Type` is the database type (string value). Supported types: `levelDB` and
   `boltDB`.
-- `LevelDBOptions` are settings for LevelDB.
-- `BoltDBOptions` configures BoltDB.
+- `LevelDBOptions` are settings for LevelDB. Includes the DB files path and ReadOnly mode toggle.
+  If ReadOnly mode is on, then an error will be returned on attempt to connect to unexisting or empty
+  database. Database doesn't allow changes in this mode, a warning will be logged on DB persist attempts.
+- `BoltDBOptions` configures BoltDB. Includes the DB files path and ReadOnly mode toggle. If ReadOnly
+  mode is on, then an error will be returned on attempt to connect with unexisting or empty database.
+  Database doesn't allow changes in this mode, a warning will be logged on DB persist attempts.
 
 Only options for the specified database type will be used.
 

pkg/core/storage/boltdb_store.go

@@ -2,6 +2,7 @@ package storage
 
 import (
 	"bytes"
+	"errors"
 	"fmt"
 	"os"
 
@@ -22,23 +23,38 @@ type BoltDBStore struct {
 
 // NewBoltDBStore returns a new ready to use BoltDB storage with created bucket.
 func NewBoltDBStore(cfg dbconfig.BoltDBOptions) (*BoltDBStore, error) {
-	var opts *bbolt.Options       // should be exposed via BoltDBOptions if anything needed
+	cp := *bbolt.DefaultOptions // Do not change bbolt's global variable.
+	opts := &cp
 	fileMode := os.FileMode(0600) // should be exposed via BoltDBOptions if anything needed
 	fileName := cfg.FilePath
-	if err := io.MakeDirForFile(fileName, "BoltDB"); err != nil {
-		return nil, err
+	if cfg.ReadOnly {
+		opts.ReadOnly = true
+	} else {
+		if err := io.MakeDirForFile(fileName, "BoltDB"); err != nil {
+			return nil, err
+		}
 	}
 	db, err := bbolt.Open(fileName, fileMode, opts)
 	if err != nil {
-		return nil, err
+		return nil, fmt.Errorf("failed to open BoltDB instance: %w", err)
+	}
+	if opts.ReadOnly {
+		err = db.View(func(tx *bbolt.Tx) error {
+			b := tx.Bucket(Bucket)
+			if b == nil {
+				return errors.New("root bucket does not exist")
+			}
+			return nil
+		})
+	} else {
+		err = db.Update(func(tx *bbolt.Tx) error {
+			_, err = tx.CreateBucketIfNotExists(Bucket)
+			if err != nil {
+				return fmt.Errorf("could not create root bucket: %w", err)
+			}
+			return nil
+		})
 	}
-	err = db.Update(func(tx *bbolt.Tx) error {
-		_, err = tx.CreateBucketIfNotExists(Bucket)
-		if err != nil {
-			return fmt.Errorf("could not create root bucket: %w", err)
-		}
-		return nil
-	})
 	if err != nil {
 		return nil, fmt.Errorf("failed to initialize BoltDB instance: %w", err)
 	}

pkg/core/storage/boltdb_store_test.go

@@ -1,11 +1,15 @@
 package storage
 
 import (
+	"os"
 	"path/filepath"
+	"strings"
 	"testing"
 
 	"github.com/nspcc-dev/neo-go/pkg/core/storage/dbconfig"
+	"github.com/nspcc-dev/neo-go/pkg/io"
 	"github.com/stretchr/testify/require"
+	"go.etcd.io/bbolt"
 )
 
 func newBoltStoreForTesting(t testing.TB) Store {
@@ -15,3 +19,42 @@ func newBoltStoreForTesting(t testing.TB) Store {
 	require.NoError(t, err)
 	return boltDBStore
 }
+
+func TestROBoltDB(t *testing.T) {
+	d := t.TempDir()
+	testFileName := filepath.Join(d, "test_ro_bolt_db")
+	cfg := dbconfig.BoltDBOptions{
+		FilePath: testFileName,
+		ReadOnly: true,
+	}
+
+	// If DB doesn't exist, then error should be returned.
+	_, err := NewBoltDBStore(cfg)
+	require.Error(t, err)
+
+	// Create the DB and try to open it in RO mode.
+	cfg.ReadOnly = false
+	store, err := NewBoltDBStore(cfg)
+	require.NoError(t, err)
+	require.NoError(t, store.Close())
+	cfg.ReadOnly = true
+
+	store, err = NewBoltDBStore(cfg)
+	require.NoError(t, err)
+	// Changes must be prohibited.
+	putErr := store.PutChangeSet(map[string][]byte{"one": []byte("one")}, nil)
+	require.ErrorIs(t, putErr, bbolt.ErrDatabaseReadOnly)
+	require.NoError(t, store.Close())
+
+	// Create the DB without buckets and try to open it in RO mode, an error is expected.
+	fileMode := os.FileMode(0600)
+	cfg.FilePath = filepath.Join(d, "clean_ro_bolt_db")
+	require.NoError(t, io.MakeDirForFile(cfg.FilePath, "BoltDB"))
+	db, err := bbolt.Open(cfg.FilePath, fileMode, nil)
+	require.NoError(t, err)
+	require.NoError(t, db.Close())
+
+	_, err = NewBoltDBStore(cfg)
+	require.Error(t, err)
+	require.True(t, strings.Contains(err.Error(), "root bucket does not exist"))
+}

pkg/core/storage/dbconfig/store_config.go

@@ -13,9 +13,11 @@ type (
 	// LevelDBOptions configuration for LevelDB.
 	LevelDBOptions struct {
 		DataDirectoryPath string `yaml:"DataDirectoryPath"`
+		ReadOnly          bool   `yaml:"ReadOnly"`
 	}
 	// BoltDBOptions configuration for BoltDB.
 	BoltDBOptions struct {
 		FilePath string `yaml:"FilePath"`
+		ReadOnly bool   `yaml:"ReadOnly"`
 	}
 )

pkg/core/storage/leveldb_store.go

@@ -2,6 +2,7 @@ package storage
 
 import (
 	"errors"
+	"fmt"
 
 	"github.com/nspcc-dev/neo-go/pkg/core/storage/dbconfig"
 	"github.com/syndtr/goleveldb/leveldb"
@@ -21,11 +22,14 @@ type LevelDBStore struct {
 // initialize the database found at the given path.
 func NewLevelDBStore(cfg dbconfig.LevelDBOptions) (*LevelDBStore, error) {
 	var opts = new(opt.Options) // should be exposed via LevelDBOptions if anything needed
-
+	if cfg.ReadOnly {
+		opts.ReadOnly = true
+		opts.ErrorIfMissing = true
+	}
 	opts.Filter = filter.NewBloomFilter(10)
 	db, err := leveldb.OpenFile(cfg.DataDirectoryPath, opts)
 	if err != nil {
-		return nil, err
+		return nil, fmt.Errorf("failed to open LevelDB instance: %w", err)
 	}
 
 	return &LevelDBStore{

pkg/core/storage/leveldb_store_test.go

@@ -5,6 +5,7 @@ import (
 
 	"github.com/nspcc-dev/neo-go/pkg/core/storage/dbconfig"
 	"github.com/stretchr/testify/require"
+	"github.com/syndtr/goleveldb/leveldb"
 )
 
 func newLevelDBForTesting(t testing.TB) Store {
@@ -16,3 +17,29 @@ func newLevelDBForTesting(t testing.TB) Store {
 	require.Nil(t, err, "NewLevelDBStore error")
 	return newLevelStore
 }
+
+func TestROLevelDB(t *testing.T) {
+	ldbDir := t.TempDir()
+	opts := dbconfig.LevelDBOptions{
+		DataDirectoryPath: ldbDir,
+		ReadOnly:          true,
+	}
+
+	// If DB doesn't exist, then error should be returned.
+	_, err := NewLevelDBStore(opts)
+	require.Error(t, err)
+
+	// Create the DB and try to open it in RO mode.
+	opts.ReadOnly = false
+	store, err := NewLevelDBStore(opts)
+	require.NoError(t, err)
+	require.NoError(t, store.Close())
+	opts.ReadOnly = true
+
+	store, err = NewLevelDBStore(opts)
+	require.NoError(t, err)
+	t.Cleanup(func() { require.NoError(t, store.Close()) })
+	// Changes must be prohibited.
+	putErr := store.PutChangeSet(map[string][]byte{"one": []byte("one")}, nil)
+	require.ErrorIs(t, putErr, leveldb.ErrReadOnly)
+}