backup: Introduce a base backup ID

This base ID will be used to find the backup to use as a base of an
incremental backup. Right now pointer layout always uses the latest
backup as a base. Specifying a base will allow extra flexibility.

9 files changed, 22 insertions, 11 deletions

diff --git a/internal/backup/backup.go b/internal/backup/backup.go
index cb1265a5e..e9b957b79 100644
--- a/internal/backup/backup.go
+++ b/internal/backup/backup.go
@@ -92,8 +92,11 @@ type Locator interface {
 	BeginFull(ctx context.Context, repo storage.Repository, backupID string) *Backup
 
 	// BeginIncremental returns the backup with the last element of Steps being
-	// the tentative step needed to create an incremental backup.
-	BeginIncremental(ctx context.Context, repo storage.Repository, backupID string) (*Backup, error)
+	// the tentative step needed to create an incremental backup. backupID will
+	// be the name of the newly created backup. baseBackupID is the name of the
+	// backup used to create an incremental backup from if supported by the
+	// layout.
+	BeginIncremental(ctx context.Context, repo storage.Repository, backupID, baseBackupID string) (*Backup, error)
 
 	// Commit persists the backup so that it can be looked up by FindLatest. It
 	// is expected that the last element of Steps will be the newly created
@@ -243,7 +246,7 @@ func (mgr *Manager) Create(ctx context.Context, req *CreateRequest) error {
 	var backup *Backup
 	if req.Incremental {
 		var err error
-		backup, err = mgr.locator.BeginIncremental(ctx, req.VanityRepository, req.BackupID)
+		backup, err = mgr.locator.BeginIncremental(ctx, req.VanityRepository, req.BackupID, req.BaseBackupID)
 		if err != nil {
 			return fmt.Errorf("manager: %w", err)
 		}
diff --git a/internal/backup/locator.go b/internal/backup/locator.go
index b2952a5f7..f2ffa3931 100644
--- a/internal/backup/locator.go
+++ b/internal/backup/locator.go
@@ -35,7 +35,7 @@ func (l LegacyLocator) BeginFull(ctx context.Context, repo storage.Repository, b
 }
 
 // BeginIncremental is not supported for legacy backups
-func (l LegacyLocator) BeginIncremental(ctx context.Context, repo storage.Repository, backupID string) (*Backup, error) {
+func (l LegacyLocator) BeginIncremental(ctx context.Context, repo storage.Repository, backupID, baseBackupID string) (*Backup, error) {
 	return nil, errors.New("legacy layout: begin incremental: not supported")
 }
 
@@ -108,7 +108,7 @@ func (l PointerLocator) BeginFull(ctx context.Context, repo storage.Repository,
 // backup.  The incremental backup is always based off of the latest full
 // backup. If there is no latest backup, a new full backup step is returned
 // using fallbackBackupID
-func (l PointerLocator) BeginIncremental(ctx context.Context, repo storage.Repository, fallbackBackupID string) (*Backup, error) {
+func (l PointerLocator) BeginIncremental(ctx context.Context, repo storage.Repository, fallbackBackupID, _baseBackupID string) (*Backup, error) {
 	repoPath := strings.TrimSuffix(repo.GetRelativePath(), ".git")
 	backupID, err := l.findLatestID(ctx, repoPath)
 	if err != nil {
@@ -286,8 +286,8 @@ func (l ManifestInteropLocator) BeginFull(ctx context.Context, repo storage.Repo
 }
 
 // BeginIncremental passes through to Fallback
-func (l ManifestInteropLocator) BeginIncremental(ctx context.Context, repo storage.Repository, backupID string) (*Backup, error) {
-	return l.Fallback.BeginIncremental(ctx, repo, backupID)
+func (l ManifestInteropLocator) BeginIncremental(ctx context.Context, repo storage.Repository, backupID, baseBackupID string) (*Backup, error) {
+	return l.Fallback.BeginIncremental(ctx, repo, backupID, baseBackupID)
 }
 
 // Commit passes through to Fallback, then writes a manifest file for the backup.
diff --git a/internal/backup/locator_test.go b/internal/backup/locator_test.go
index cb7f5c4ed..4c49a17a5 100644
--- a/internal/backup/locator_test.go
+++ b/internal/backup/locator_test.go
@@ -184,7 +184,7 @@ func TestPointerLocator(t *testing.T) {
 						previousRefPath = step.RefPath
 					}
 
-					step, err := l.BeginIncremental(ctx, repo, fallbackBackupID)
+					step, err := l.BeginIncremental(ctx, repo, fallbackBackupID, "")
 					require.NoError(t, err)
 					require.Equal(t, expected, step)
 
@@ -465,7 +465,7 @@ custom_hooks_path = '%[1]s/%[2]s/001.custom_hooks.tar'
 			Fallback: l,
 		}
 
-		incremental, err := l.BeginIncremental(ctx, repo, backupID)
+		incremental, err := l.BeginIncremental(ctx, repo, backupID, "")
 		require.NoError(t, err)
 		require.NoError(t, l.Commit(ctx, incremental))
 
diff --git a/internal/backup/pipeline.go b/internal/backup/pipeline.go
index 8e4e15784..9d98c1008 100644
--- a/internal/backup/pipeline.go
+++ b/internal/backup/pipeline.go
@@ -33,6 +33,9 @@ type CreateRequest struct {
 	// BackupID is used to determine a unique path for the backup when a full
 	// backup is created.
 	BackupID string
+	// BaseBackupID is used to determine the backup used to use as the base of
+	// an incremental backup if supported by the selected layout.
+	BaseBackupID string
 }
 
 // RestoreRequest is the request to restore from a backup
diff --git a/internal/backup/server_side.go b/internal/backup/server_side.go
index 35654f215..1e58f7c86 100644
--- a/internal/backup/server_side.go
+++ b/internal/backup/server_side.go
@@ -42,6 +42,7 @@ func (ss ServerSideAdapter) Create(ctx context.Context, req *CreateRequest) erro
 		VanityRepository: req.VanityRepository,
 		BackupId:         req.BackupID,
 		Incremental:      req.Incremental,
+		BaseBackupId:     req.BaseBackupID,
 	})
 	if err != nil {
 		st := status.Convert(err)
diff --git a/internal/bundleuri/git_config_test.go b/internal/bundleuri/git_config_test.go
index c14c3625b..cea6be8e1 100644
--- a/internal/bundleuri/git_config_test.go
+++ b/internal/bundleuri/git_config_test.go
@@ -159,7 +159,7 @@ func (l dummyLocator) BeginFull(ctx context.Context, repo storage.Repository, ba
 }
 
 // BeginIncremental is not supported by this dummyLocator.
-func (l dummyLocator) BeginIncremental(ctx context.Context, repo storage.Repository, backupID string) (*backup.Backup, error) {
+func (l dummyLocator) BeginIncremental(ctx context.Context, repo storage.Repository, backupID, baseBackupID string) (*backup.Backup, error) {
 	return nil, structerr.NewUnimplemented("BeginIncremental not implemented for dummyLocator")
 }
 
diff --git a/internal/cli/gitalybackup/create.go b/internal/cli/gitalybackup/create.go
index e1a6ec823..c8194191c 100644
--- a/internal/cli/gitalybackup/create.go
+++ b/internal/cli/gitalybackup/create.go
@@ -31,6 +31,7 @@ type createSubcommand struct {
 	layout          string
 	incremental     bool
 	backupID        string
+	baseBackupID    string
 	serverSide      bool
 }
 
@@ -41,6 +42,7 @@ func (cmd *createSubcommand) flags(ctx *cli.Context) {
 	cmd.layout = ctx.String("layout")
 	cmd.incremental = ctx.Bool("incremental")
 	cmd.backupID = ctx.String("id")
+	cmd.baseBackupID = ctx.String("base-id")
 	cmd.serverSide = ctx.Bool("server-side")
 }
 
@@ -168,6 +170,7 @@ func (cmd *createSubcommand) run(ctx context.Context, logger log.Logger, stdin i
 			VanityRepository: &repo,
 			Incremental:      cmd.incremental,
 			BackupID:         cmd.backupID,
+			BaseBackupID:     cmd.baseBackupID,
 		}))
 	}
 
diff --git a/internal/gitaly/service/repository/backup_repository.go b/internal/gitaly/service/repository/backup_repository.go
index 60b0314ca..880a60c98 100644
--- a/internal/gitaly/service/repository/backup_repository.go
+++ b/internal/gitaly/service/repository/backup_repository.go
@@ -36,6 +36,7 @@ func (s *server) BackupRepository(ctx context.Context, in *gitalypb.BackupReposi
 		VanityRepository: in.VanityRepository,
 		BackupID:         in.BackupId,
 		Incremental:      in.Incremental,
+		BaseBackupID:     in.BaseBackupId,
 	})
 
 	switch {
diff --git a/internal/gitaly/service/smarthttp/upload_pack_test.go b/internal/gitaly/service/smarthttp/upload_pack_test.go
index 47178ece6..6e9748d8d 100644
--- a/internal/gitaly/service/smarthttp/upload_pack_test.go
+++ b/internal/gitaly/service/smarthttp/upload_pack_test.go
@@ -386,7 +386,7 @@ func (l *mockBackupLocator) BeginFull(ctx context.Context, repo storage.Reposito
 	return l.backup
 }
 
-func (l *mockBackupLocator) BeginIncremental(ctx context.Context, repo storage.Repository, backupID string) (*backup.Backup, error) {
+func (l *mockBackupLocator) BeginIncremental(ctx context.Context, repo storage.Repository, backupID, baseBackupID string) (*backup.Backup, error) {
 	return nil, nil
 }