Usage with Sidekiq::Web

Sidekiq docs does not (yet) feature an example for Passwordless, but their restful authentication or sorcery example is pretty close to a working solution. This is how I did it:

# app/models/user.rb

class User < ApplicationRecord
  validates :email, presence: true, uniqueness: { case_sensitive: false }

  passwordless_with :email

  # Treating all users as admins to make the example short. This part will likely look different in your app ✌️
  def admin?
    true
  end
end

# lib/admin_constraint.rb

class AdminConstraint
  def matches?(request)
    passwordless_session_id = request.session['passwordless_session_id--user']
    return false unless passwordless_session_id

    user = Passwordless::Session.find(passwordless_session_id).authenticatable
    user&.admin?
  end
end

# config/routes.rb

require 'sidekiq/web'
require 'admin_constraint'

Rails.application.routes.draw do
  passwordless_for :users
  mount Sidekiq::Web => '/sidekiq', constraints: AdminConstraint.new
  ...
end