APIs normally accept your login request and send you an authentication token which you need to pass back in each call. This is very similar to cookie based sessions where your browser automatically passes back the cookie which is acquired on initial website visit.
From what I've seen in Sinatra's docs, you could make a session-based authentication system like this:
enable :session
disable :show_exceptions
use Rack::Session::Pool,
key: 'session_id'
post '/login' do
user = User.login_success(params)
halt 401 if user.nil?
session[:user] = user
200
end
get '/fun' do
user = session[:user]
halt 401 if user.nil?
halt 403 if !user.has_permission_for '/fun'
"fun was had"
end
Now all you need to do in your client is to pass back the cookie token returned in response to initial visit when requesting an API function. This can be done with any web client library that supports cookie stores (such as libcurl) or by inserting the session cookie into the request header manually. Rack::Minitest functionality also supports cookies, so you can test your API with minitest.
