kubernetes/vendor/google.golang.org/grpc/internal/tcp_keepalive_unix.go

// NetDialerWithTCPKeepalive returns a net.Dialer that enables TCP keepalives on
// the underlying connection with OS default values for keepalive parameters.
//
// TODO: Once https://github.com/golang/go/issues/62254 lands, and the
// appropriate Go version becomes less than our least supported Go version, we
// should look into using the new API to make things more straightforward.
func NetDialerWithTCPKeepalive() *net.Dialer { … }