Horizontal Stackview left align items

I am creating a horizontal UIStackView and want to left align items in it. Here is my code:

let nameLabel: UILabel = {
    let label=UILabel()
    label.text = "First Name:"
    label.textColor = UIColor.black
    label.font = UIFont.systemFont(ofSize: 20)
    label.textAlignment = .left
    label.translatesAutoresizingMaskIntoConstraints=false
    return label
}()

let nameTextField: UITextField = {
    let label=UITextField()
    label.placeholder = "Enter Name"
    label.textColor = UIColor.darkGray
    label.font = UIFont.systemFont(ofSize: 18)
    label.textAlignment = .left
    label.isUserInteractionEnabled = false
    label.translatesAutoresizingMaskIntoConstraints=false
    return label
}()

lazy var firstNameView: UIStackView = {
    let stackView = UIStackView(arrangedSubviews: [self.nameLabel, self.nameTextField])
    stackView.translatesAutoresizingMaskIntoConstraints = false;
    stackView.axis = .horizontal
    stackView.distribution = .fill
    stackView.alignment = .center
    stackView.spacing = 10.0
    return stackView
}()

And here is how i add it to the view

self.view.addSubview(firstNameView)

firstNameView.leadingAnchor.constraint(equalTo: self.view.leadingAnchor).isActive = true;
    firstNameView.topAnchor.constraint(equalTo: idLabel.bottomAnchor).isActive = true;
    firstNameView.trailingAnchor.constraint(equalTo: self.view.trailingAnchor).isActive = true
    firstNameView.heightAnchor.constraint(equalToConstant: 40.0).isActive = true

I also tried the following:

firstNameView.trailingAnchor.constraint(greaterThanOrEqualTo: self.view.trailingAnchor).isActive = true

PS: This question is different from UIStackview align left as i am talking about horizontal stackview

According to this link Left aligned horizontal stackview and top aligned vertical stackview Is there any alternative, i don't really want to set a fixed width.