Function CheckLatestVersion

coderd/database/migrations/migrate.go:201–234

Returns nil if currentVersion corresponds to the latest available migration, otherwise an error explaining why not.

(sourceDriver source.Driver, currentVersion uint)

// Returns nil if currentVersion corresponds to the latest available migration,
// otherwise an error explaining why not.
func CheckLatestVersion(sourceDriver source.Driver, currentVersion uint) error {
	// This is ugly, but seems like the only way to do it with the public
	// interfaces provided by golang-migrate.

	// Check that there is no later version
	nextVersion, err := sourceDriver.Next(currentVersion)
	if err == nil {
		return xerrors.Errorf("current version is %d, but later version %d exists", currentVersion, nextVersion)
	}
	if !errors.Is(err, os.ErrNotExist) {
		return xerrors.Errorf("get next migration after %d: %w", currentVersion, err)
	}

	// Once we reach this point, we know that either currentVersion doesn't
	// exist, or it has no successor (the return value from
	// sourceDriver.Next() is the same in either case). So we need to check
	// that either it's the first version, or it has a predecessor.

	firstVersion, err := sourceDriver.First()
	if err != nil {
		// the total number of migrations should be non-zero, so this must be
		// an actual error, not just a missing file
		return xerrors.Errorf("get first migration: %w", err)
	}
	if firstVersion == currentVersion {
		return nil
	}

	_, err = sourceDriver.Prev(currentVersion)
	if err != nil {
		return xerrors.Errorf("get previous migration: %w", err)
	}
	return nil
}

// Stepper returns a function that runs SQL migrations one step at a time.
//