Function ResolveDialContext

internal/bootstrap/bootstrap.go:48–93

ResolveDialContext returns a DialHandler that uses addresses resolved from u using resolver. l and u must not be nil.

(
	u *url.URL,
	timeout time.Duration,
	r Resolver,
	preferV6 bool,
	l *slog.Logger,
)

// ResolveDialContext returns a DialHandler that uses addresses resolved from u
// using resolver.  l and u must not be nil.
func ResolveDialContext(
	u *url.URL,
	timeout time.Duration,
	r Resolver,
	preferV6 bool,
	l *slog.Logger,
) (h DialHandler, err error) {
	defer func() { err = errors.Annotate(err, "dialing %q: %w", u.Host) }()

	host, port, err := netutil.SplitHostPort(u.Host)
	if err != nil {
		// Don't wrap the error since it's informative enough as is and there is
		// already deferred annotation here.
		return nil, err
	}

	if r == nil {
		return nil, fmt.Errorf("resolver is nil: %w", ErrNoResolvers)
	}

	ctx := context.Background()
	if timeout > 0 {
		var cancel func()
		ctx, cancel = context.WithTimeout(ctx, timeout)
		defer cancel()
	}

	// TODO(e.burkov):  Use network properly, perhaps, pass it through options.
	ips, err := r.LookupNetIP(ctx, NetworkIP, host)
	if err != nil {
		return nil, fmt.Errorf("resolving hostname: %w", err)
	}

	if preferV6 {
		slices.SortStableFunc(ips, netutil.PreferIPv6)
	} else {
		slices.SortStableFunc(ips, netutil.PreferIPv4)
	}

	addrs := make([]string, 0, len(ips))
	for _, ip := range ips {
		addrs = append(addrs, netip.AddrPortFrom(ip, port).String())
	}

	return NewDialContext(timeout, l, addrs...), nil
}

// NewDialContext returns a DialHandler that dials addrs and returns the first
// successful connection.  At least a single addr should be specified.  l must