Remove database on schema creation failure

internal/users/db/db.go

@@ -73,6 +73,11 @@ func New(dbDir string) (*Manager, error) {
 		log.Debugf(context.Background(), "Creating new SQLite database at %v", dbPath)
 		_, err = db.Exec(createSchema)
 		if err != nil {
+			// Remove the database file if we failed to create the schema, to avoid that authd tries to use a broken
+			// database on the next start.
+			if removeErr := os.Remove(dbPath); removeErr != nil {
+				log.Warningf(context.Background(), "Failed to remove database file after failed schema creation: %v", removeErr)
+			}
 			return nil, fmt.Errorf("failed to create schema: %w", err)
 		}
 	}

internal/users/db/db_test.go

@@ -9,6 +9,7 @@ import (
 	"testing"
 
 	"github.com/stretchr/testify/require"
+	"github.com/ubuntu/authd/internal/fileutils"
 	"github.com/ubuntu/authd/internal/testutils/golden"
 	"github.com/ubuntu/authd/internal/users/db"
 	"github.com/ubuntu/authd/log"
@@ -91,6 +92,25 @@ func TestNew(t *testing.T) {
 	}
 }
 
+func TestDatabaseRemovedWhenSchemaCreationFails(t *testing.T) {
+	// Don't run this test in parallel because it writes a global variable (via db.SetCreateSchemaQuery)
+	origQuery := db.GetCreateSchemaQuery()
+	db.SetCreateSchemaQuery("invalid query")
+	t.Cleanup(func() {
+		db.SetCreateSchemaQuery(origQuery)
+	})
+
+	dbDir := t.TempDir()
+	dbDestPath := filepath.Join(dbDir, db.Z_ForTests_DBName())
+
+	_, err := db.New(dbDir)
+	require.Error(t, err, "New should return an error when schema creation fails")
+
+	exists, err := fileutils.FileExists(dbDestPath)
+	require.NoError(t, err, "Failed to check if database file exists")
+	require.False(t, exists, "Database file should not exist after failed schema creation")
+}
+
 func TestUpdateUserEntry(t *testing.T) {
 	t.Parallel()
 

internal/users/db/export_test.go

@@ -4,3 +4,13 @@ package db
 func (m *Manager) Path() string {
 	return m.path
 }
+
+// GetCreateSchemaQuery exposes the query to create the schema for testing.
+func GetCreateSchemaQuery() string {
+	return createSchema
+}
+
+// SetCreateSchemaQuery sets the query to create the schema for testing.
+func SetCreateSchemaQuery(query string) {
+	createSchema = query
+}