Configure gem for ActiveAdmin

app/admin/user.rb

@@ -12,6 +12,9 @@
     column :username
     column :role
     column :authy_enabled
+    column do |user|
+      link_to("Sign in as #{user.name}", impersonate_engine.impersonate_user_path(user))
+    end
   end
 
   filter :email

app/models/admin_user.rb

@@ -4,4 +4,8 @@ class AdminUser < ActiveRecord::Base
   devise :authy_authenticatable, :database_authenticatable, :trackable, :validatable
 
   validates :email, presence: true
+
+  def staff?
+    true
+  end
 end

config/initializers/user_impersonate.rb

@@ -0,0 +1,40 @@
+module UserImpersonate
+  class Engine < Rails::Engine
+    # Devise user model
+    config.user_class = 'User'
+
+    # User model lookup method
+    config.user_finder = 'find'
+
+    # Staff user model lookup method
+    config.staff_finder = 'find'
+
+    # User model primary key attribute
+    config.user_id_column = 'id'
+
+    # User model name attribute used for search
+    # Usage: User.where('#{user_name_column} like ?', '%#{params[:search]}%')
+    config.user_name_column = 'name'
+
+    # User model staff attribute
+    config.user_is_staff_method = 'staff?'
+
+    # Redirect to this path when entering impersonate mode
+    config.redirect_on_impersonate = '/'
+
+    # Redirect to this path when leaving impersonate mode
+    config.redirect_on_revert = '/manage/users'
+
+    # Devise method used to sign user in
+    config.sign_in_user_method = 'sign_in'
+
+    # For Active Admin "AdminUser" model, use 'AdminUser'
+    config.staff_class = 'AdminUser'
+
+    # For Active Admin "AdminUser" model, use 'authenticate_admin_user!'
+    config.authenticate_user_method = 'authenticate_admin_user!'
+
+    # For Active Admin "AdminUser" model, use 'current_admin_user'
+    config.current_staff = 'current_admin_user'
+  end
+end