Due to requirements with our reverse proxies, I had to show the user login form on a different URL. Well, no problem, I thought, I'll just copy the relevant section from
user.routing.yml and display it on a different path:
mymodule.user.login: path: '/ls/login' defaults: _form: '\Drupal\user\Form\UserLoginForm' _title: 'Log in' requirements: _user_is_logged_in: 'FALSE' options: _maintenance_access: TRUE
This works, but if an user accesses the login URL after having logged in (typically because they bookmarked the login page), they get an "Access denied" page. I can understand it – after all, there is the requirement that the user is NOT logged is. I was thinking of ways to circumvent this, but then I noticed that the original URL (still accessible if I access the server directly rather than through the proxies) does not have this problem: if I go to
/usr/login it after logging in, I get redirected to the user page,
I don't understand how the latter works, I looked at
UserLoginForm.php in addition to
user.login.form, but I found no clue. What is involved here?