Have you actually tryed searching the Authentication / Security section where there are tons and tons of threads on the subject already? But here we go again:

<?php namespace App\Http\Controllers\Auth;
use Illuminate\Http\Request;
use App\Http\Controllers\Controller;
use Illuminate\Contracts\Auth\Guard;
use Illuminate\Contracts\Auth\Registrar;
use Illuminate\Foundation\Auth\AuthenticatesAndRegistersUsers;

class AuthController extends Controller {

	/*
	|--------------------------------------------------------------------------
	| Registration & Login Controller
	|--------------------------------------------------------------------------
	|
	| This controller handles the registration of new users, as well as the
	| authentication of existing users. By default, this controller uses
	| a simple trait to add these behaviors. Why don't you explore it?
	|
	*/

	use AuthenticatesAndRegistersUsers;

	/**
	 * Create a new authentication controller instance.
	 *
	 * @param  \Illuminate\Contracts\Auth\Guard  $auth
	 * @param  \Illuminate\Contracts\Auth\Registrar  $registrar
	 * @return void
	 */
	public function __construct(Guard $auth, Registrar $registrar)
	{
		$this->auth = $auth;
		$this->registrar = $registrar;

		$this->middleware('guest', ['except' => 'getLogout']);
	}
        
        
           public function getLogin()
	{
		return view('auth.login');
                //return view('auth.testview');
	}
        
        public function postLogin(Request $request)
	{
		$this->validate($request, [
			'userid' => 'required', 'password' => 'required',
		]);
                
                //added
                
             $tvar = $request->input('userid');
             $pw = $request->input('password');
            if ($this->auth->attempt(['userid' => $tvar, 'password' => $pw]))
		{
                    //echo 'logged in========'.$request->user->userid;
                    echo 'logged in========'.$request->user()->userid;
                    $yourvar = $request->user()->userid;
                    echo $yourvar;
                    echo "====loggin in now";
                    return redirect('pets');
		}
            else
                {
                    echo ' not logged in';
                }

                //added

		/*$credentials = $request->only('email', 'password');

		if ($this->auth->attempt($credentials, $request->has('remember')))
		{
			return redirect($this->redirectPath());
		}

		return redirect('/auth/login')
					->withInput($request->only('email'))
					->withErrors([
						'email' => 'These credentials do not match our records.',
					]);*/
	}
        
        public function getLogout()
	{
		$this->auth->logout();

		return redirect('/');
	}



}//end class

Like this, nothing else. I use userid, NOT email.
By the way docs are not up to date on auth.

Thanks a lot