cmd/lxd-to-incus: Uncompress snapshot files in the target database

Signed-off-by: Free Ekanayaka <[email protected]>

cmd/lxd-to-incus/db.go

@@ -0,0 +1,100 @@
+package main
+
+import (
+	"fmt"
+	"github.com/lxc/incus/shared"
+	"github.com/pierrec/lz4/v4"
+	"io"
+	"io/ioutil"
+	"os"
+	"path/filepath"
+)
+
+// Uncompress the raft snapshot files in the given database directory.
+//
+// A backup will be created and kept around in case of errors.
+func migrateDatabase(dir string) error {
+	global := filepath.Join(dir, "global")
+
+	err := shared.DirCopy(global, global+".bak")
+	if err != nil {
+		return fmt.Errorf("Failed to backup database directory %q: %w", global, err)
+	}
+
+	files, err := ioutil.ReadDir(global)
+	if err != nil {
+		return fmt.Errorf("Failed to list database directory %q: %w", global, err)
+	}
+
+	for _, file := range files {
+		var timestamp uint64
+		var first uint64
+		var last uint64
+
+		if !file.Mode().IsRegular() {
+			continue
+		}
+
+		n, err := fmt.Sscanf(file.Name(), "snapshot-%d-%d-%d\n", &timestamp, &first, &last)
+		if err != nil || n != 3 {
+			continue
+		}
+
+		filename := filepath.Join(global, file.Name())
+		err = uncompress(filename)
+		if err != nil {
+			return fmt.Errorf("Failed to uncompress snapshot %q: %w", filename, err)
+		}
+	}
+
+	return nil
+}
+
+// Uncompress the given file, preserving its mode and ownership.
+func uncompress(zfilename string) error {
+	zr := lz4.NewReader(nil)
+
+	zfile, err := os.Open(zfilename)
+	if err != nil {
+		return fmt.Errorf("Failed to open file %q: %w", zfilename, err)
+	}
+	zinfo, err := zfile.Stat()
+	if err != nil {
+		return fmt.Errorf("Fialed to get file info for %q: %w", zfilename, err)
+	}
+	mode := zinfo.Mode() // use the same mode for the output file
+
+	_, uid, gid := shared.GetOwnerMode(zinfo)
+
+	filename := zfilename + ".uncompressed"
+	file, err := os.OpenFile(filename, os.O_CREATE|os.O_WRONLY|os.O_TRUNC, mode)
+	if err != nil {
+		return fmt.Errorf("Failed to open file %q: %w", filename, err)
+	}
+
+	zr.Reset(zfile)
+
+	_, err = io.Copy(file, zr)
+	if err != nil {
+		return fmt.Errorf("Failed to uncompress %q into %q: %w", zfilename, filename, err)
+	}
+
+	for _, c := range []io.Closer{zfile, file} {
+		err := c.Close()
+		if err != nil {
+			return fmt.Errorf("Failed to close file: %w", err)
+		}
+	}
+
+	err = os.Chown(filename, uid, gid)
+	if err != nil {
+		return fmt.Errorf("Failed to set ownership of %q: %w", filename, err)
+	}
+
+	err = os.Rename(filename, zfilename)
+	if err != nil {
+		return fmt.Errorf("Failed to rename %q to %q: %w", filename, zfilename, err)
+	}
+
+	return nil
+}

cmd/lxd-to-incus/go.mod

@@ -28,6 +28,7 @@ require (
 	github.com/muhlemmer/gu v0.3.1 // indirect
 	github.com/olekukonko/tablewriter v0.0.5 // indirect
 	github.com/pborman/uuid v1.2.1 // indirect
+	github.com/pierrec/lz4/v4 v4.1.18 // indirect
 	github.com/pkg/sftp v1.13.6 // indirect
 	github.com/pkg/xattr v0.4.9 // indirect
 	github.com/rivo/uniseg v0.4.4 // indirect

cmd/lxd-to-incus/go.sum

@@ -96,6 +96,8 @@ github.com/olekukonko/tablewriter v0.0.5 h1:P2Ga83D34wi1o9J6Wh1mRuqd4mF/x/lgBS7N
 github.com/olekukonko/tablewriter v0.0.5/go.mod h1:hPp6KlRPjbx+hW8ykQs1w3UBbZlj6HuIJcUGPhkA7kY=
 github.com/pborman/uuid v1.2.1 h1:+ZZIw58t/ozdjRaXh/3awHfmWRbzYxJoAdNJxe/3pvw=
 github.com/pborman/uuid v1.2.1/go.mod h1:X/NO0urCmaxf9VXbdlT7C2Yzkj2IKimNn4k+gtPdI/k=
+github.com/pierrec/lz4/v4 v4.1.18 h1:xaKrnTkyoqfh1YItXl56+6KJNVYWlEEPuAQW9xsplYQ=
+github.com/pierrec/lz4/v4 v4.1.18/go.mod h1:gZWDp/Ze/IJXGXf23ltt2EXimqmTUXEy0GFuRQyBid4=
 github.com/pkg/sftp v1.13.6 h1:JFZT4XbOU7l77xGSpOdW+pwIMqP044IyjXX6FGyEKFo=
 github.com/pkg/sftp v1.13.6/go.mod h1:tz1ryNURKu77RL+GuCzmoJYxQczL3wLNNpPWagdg4Qk=
 github.com/pkg/xattr v0.4.9 h1:5883YPCtkSd8LFbs13nXplj9g9tlrwoJRjgpgMu1/fE=

cmd/lxd-to-incus/main.go

@@ -395,6 +395,11 @@ Instances will come back online once the migration is complete.
 		return fmt.Errorf("Failed to move %q to %q: %w", sourcePaths.Daemon, targetPaths.Daemon, err)
 	}
 
+	err = migrateDatabase(filepath.Join(targetPaths.Daemon, "database"))
+	if err != nil {
+		return fmt.Errorf("Failed to migrate database in %q: %w", filepath.Join(targetPaths.Daemon, "database"), err)
+	}
+
 	// Cleanup paths.
 	fmt.Println("=> Cleaning up target paths")