From 37c52dd439b17157124fb7f4fe7af957d45f4a7f Mon Sep 17 00:00:00 2001
From: Dane Everitt <dane@daneeveritt.com>
Date: Sun, 4 Jul 2021 14:07:03 -0700
Subject: [PATCH] Shore up the logic for migrations to allow multiple passes if
 needed

---
 cmd/migrate_vhd.go  | 62 +++++++++++++++++++++++++++++++--------------
 internal/vhd/vhd.go |  8 ++++++
 2 files changed, 51 insertions(+), 19 deletions(-)

diff --git a/cmd/migrate_vhd.go b/cmd/migrate_vhd.go
index 6f3dc2e..7a487ae 100644
--- a/cmd/migrate_vhd.go
+++ b/cmd/migrate_vhd.go
@@ -54,10 +54,12 @@ func (m *MigrateVHDCommand) Run(ctx context.Context) error {
 		s.Log().Debug("starting migration of server contents to virtual disk...")
 
 		v := vhd.New(s.DiskSpace(), filesystem.VirtualDiskPath(s.Id()), s.Filesystem().Path())
+		s.Log().WithField("disk_image", v.Path()).Info("creating virtual disk for server")
 		if err := v.Allocate(ctx); err != nil {
 			return errors.WithStackIf(err)
 		}
 
+		s.Log().Info("creating virtual filesystem for server")
 		if err := v.MakeFilesystem(ctx); err != nil {
 			// If the filesystem already exists no worries, just move on with our
 			// day here.
@@ -67,19 +69,26 @@ func (m *MigrateVHDCommand) Run(ctx context.Context) error {
 		}
 
 		bak := strings.TrimSuffix(s.Filesystem().Path(), "/") + "_bak"
-		// Create a backup directory of the server files if one does not already exist
-		// at that location. If one does exists we'll just assume it is good to go and
-		// rely on it to provide the files we'll need.
-		if _, err := os.Lstat(bak); os.IsNotExist(err) {
-			if err := os.Rename(s.Filesystem().Path(), bak); err != nil {
-				return errors.Wrap(err, "failed to rename existing data directory for backup")
+		mounted, err := v.IsMounted(ctx)
+		if err != nil {
+			return err
+		} else if !mounted {
+			s.Log().WithField("backup_dir", bak).Debug("virtual disk is not yet mounted, creating backup directory")
+			// Create a backup directory of the server files if one does not already exist
+			// at that location. If one does exists we'll just assume it is good to go and
+			// rely on it to provide the files we'll need.
+			if _, err := os.Lstat(bak); os.IsNotExist(err) {
+				if err := os.Rename(s.Filesystem().Path(), bak); err != nil {
+					return errors.Wrap(err, "failed to rename existing data directory for backup")
+				}
+			} else if err != nil {
+				return errors.WithStack(err)
 			}
-		} else if err != nil {
-			return errors.WithStack(err)
-		}
-
-		if err := os.RemoveAll(s.Filesystem().Path()); err != nil && !os.IsNotExist(err) {
-			return errors.Wrap(err, "failed to remove base server files path")
+			if err := os.RemoveAll(s.Filesystem().Path()); err != nil && !os.IsNotExist(err) {
+				return errors.Wrap(err, "failed to remove base server files path")
+			}
+		} else {
+			s.Log().Warn("server appears to already have existing mount, not creating data backup")
 		}
 
 		// Attempt to mount the disk at the expected path now that we've created
@@ -88,14 +97,29 @@ func (m *MigrateVHDCommand) Run(ctx context.Context) error {
 			return errors.WithStackIf(err)
 		}
 
-		// Copy over the files from the backup for this server.
-		cmd := exec.CommandContext(ctx, "mv", bak + "/*", s.Filesystem().Path())
-		s.Log().Debug(cmd.String())
-		if err := cmd.Run(); err != nil {
-			return errors.Wrap(err, "migrate: failed to move old server files into new direcotry")
+		// Copy over the files from the backup for this server but only
+		// if we have a backup directory currently.
+		_, err = os.Lstat(bak)
+		if err != nil {
+			if !os.IsNotExist(err) {
+				s.Log().WithField("error", err).Warn("failed to stat backup directory")
+			} else {
+				s.Log().Info("no backup data directory exists, not restoring files")
+			}
+		} else {
+			cmd := exec.CommandContext(ctx, "cp", "-r", bak+"/.", s.Filesystem().Path())
+			if err := cmd.Run(); err != nil {
+				return errors.Wrap(err, "migrate: failed to move old server files into new direcotry")
+			} else {
+				if err := os.RemoveAll(bak); err != nil {
+					s.Log().WithField("directory", bak).WithField("error", err).Warn("failed to remove backup directory")
+				}
+			}
 		}
-		if err := os.Remove(bak); err != nil {
-			s.Log().WithField("directory", bak).Warn("failed to remove backup directory")
+
+		s.Log().Info("updating server file ownership...")
+		if err := s.Filesystem().Chown("/"); err != nil {
+			s.Log().WithField("error", err).Warn("failed to update ownership of new server files")
 		}
 
 		s.Log().Info("finished migration to virtual disk...")
diff --git a/internal/vhd/vhd.go b/internal/vhd/vhd.go
index 39dfed5..be4d016 100644
--- a/internal/vhd/vhd.go
+++ b/internal/vhd/vhd.go
@@ -95,6 +95,14 @@ func WithCommander(c CommanderProvider) func(*Disk) {
 	}
 }
 
+func (d *Disk) Path() string {
+	return d.diskPath
+}
+
+func (d *Disk) MountPath() string {
+	return d.mountAt
+}
+
 // Exists reports if the disk exists on the system yet or not. This only verifies
 // the presence of the disk image, not the validity of it. An error is returned
 // if the path exists but the destination is not a file or is a symlink.