What is a very simple authentication scheme for Sinatra/Rack - ruby

Question

I am busy porting a very small web app from ASP.NET MVC 2 to Ruby/Sinatra.
In the MVC app, FormsAuthentication.SetAuthCookie was being used to set a persistent cookie when the users login was validated correctly against the database.
I was wondering what the equivalent of Forms Authentication would be in Sinatra? All the authentication frameworks seem very bulky and not really what I'm looking for.

Answer 1

Here is a very simple authentication scheme for Sinatra.
I’ll explain how it works below.
class App < Sinatra::Base
set :sessions => true
register do
def auth (type)
condition do
redirect "/login" unless send("is_#{type}?")
end
end
end
helpers do
def is_user?
#user != nil
end
end
before do
#user = User.get(session[:user_id])
end
get "/" do
"Hello, anonymous."
end
get "/protected", :auth => :user do
"Hello, #{#user.name}."
end
post "/login" do
session[:user_id] = User.authenticate(params).id
end
get "/logout" do
session[:user_id] = nil
end
end
For any route you want to protect, add the :auth => :user condition to it, as in the /protected example above. That will call the auth method, which adds a condition to the route via condition.
The condition calls the is_user? method, which has been defined as a helper. The method should return true or false depending on whether the session contains a valid account id. (Calling helpers dynamically like this makes it simple to add other types of users with different privileges.)
Finally, the before handler sets up a #user instance variable for every request for things like displaying the user’s name at the top of each page. You can also use the is_user? helper in your views to determine if the user is logged in.

Answer 2

Todd's answer does not work for me, and I found an even simpler solution for one-off dead simple authentication in Sinatra's FAQ:
require 'rubygems'
require 'sinatra'
use Rack::Auth::Basic, "Restricted Area" do |username, password|
[username, password] == ['admin', 'admin']
end
get '/' do
"You're welcome"
end
I thought I would share it just in case anyone wandered this question and needed a non-persistent solution.

Answer 3

I' have found this tutorial and repository with a full example, its working fine for me
https://sklise.com/2013/03/08/sinatra-warden-auth/
https://github.com/sklise/sinatra-warden-example

Answer 4

I used the accepted answer for an app that just had 2 passwords, one for users and one for admins. I just made a login form that takes a password(or pin) and compared that to one that I had set in sinatra's settings (one for admin, one for user). Then I set the session[:current_user] to either admin or user according to which password the user entered and authorized accordingly. I didn't even need a user model. I did have to do something like this:
use Rack::Session::Cookie, :key => 'rack.session',
:domain => 'foo.com',
:path => '/',
:expire_after => 2592000, # In seconds
:secret => 'change_me'
As mentioned in the sinatra documentation to get the session to persist in chrome. With that added to my main file, they persist as expected.

Answer 5

I found JWT to be the simple, modern/secure solution I was searching for. OP mentioned bulky frameworks, so for reference I downloaded the tag of the latest jwt gem at the time of writing (2.2.3) and it's 73 KB zipped and 191 KB unzipped. Seems to be well-maintained and open sourced on GitHub.
Here's a good blog post about it with code and a walkthrough for near-beginners: https://auth0.com/blog/ruby-authentication-secure-rack-apps-with-jwt/