shelley: run schema migrations in a transaction

Philip Zeyliger and Shelley created 3 months ago

Prompt: exed now runs its schema migrations in a transaction; we should do the same for shelley.

Each migration now runs within a single transaction that:
1. Executes the migration SQL
2. Records it in the migrations table

If either step fails, the entire migration is rolled back.
This matches the pattern used by exed's migration system.

Co-authored-by: Shelley <[e-mail]>

Change summary

db/db.go | 28 +++++++++++++++-------------
1 file changed, 15 insertions(+), 13 deletions(-)

Detailed changes

db/db.go

@@ -178,13 +178,8 @@ func (db *DB) Migrate(ctx context.Context) error {
 
 		if !executedMigrations[migrationNumber] {
 			slog.Info("running migration", "file", migration, "number", migrationNumber)
-			if err := db.executeMigration(ctx, migration); err != nil {
-				return fmt.Errorf("failed to execute migration %s: %w", migration, err)
-			}
-
-			err = db.pool.Exec(ctx, "INSERT INTO migrations (migration_number, migration_name) VALUES (?, ?)", migrationNumber, migration)
-			if err != nil {
-				return fmt.Errorf("failed to record migration %s in migrations table: %w", migration, err)
+			if err := db.runMigration(ctx, migration, migrationNumber); err != nil {
+				return err
 			}
 		}
 	}
@@ -192,18 +187,25 @@ func (db *DB) Migrate(ctx context.Context) error {
 	return nil
 }
 
-// executeMigration executes a single migration file
-func (db *DB) executeMigration(ctx context.Context, filename string) error {
+// runMigration executes a single migration file within a transaction,
+// including recording it in the migrations table.
+func (db *DB) runMigration(ctx context.Context, filename string, migrationNumber int) error {
 	content, err := schemaFS.ReadFile("schema/" + filename)
 	if err != nil {
 		return fmt.Errorf("failed to read migration file %s: %w", filename, err)
 	}
 
-	if err := db.pool.Exec(ctx, string(content)); err != nil {
-		return fmt.Errorf("failed to execute migration %s: %w", filename, err)
-	}
+	return db.pool.Tx(ctx, func(ctx context.Context, tx *Tx) error {
+		if _, err := tx.Exec(string(content)); err != nil {
+			return fmt.Errorf("failed to execute migration %s: %w", filename, err)
+		}
 
-	return nil
+		if _, err := tx.Exec("INSERT INTO migrations (migration_number, migration_name) VALUES (?, ?)", migrationNumber, filename); err != nil {
+			return fmt.Errorf("failed to record migration %s in migrations table: %w", filename, err)
+		}
+
+		return nil
+	})
 }
 
 // Pool returns the underlying connection pool for advanced operations