Session cookies parameters are important both if you have a need to maintain session while getting from one
subdomain to another or when, in contrary, you host backend app under /admin
URL and want handle session
separately.
$config = [ // ... 'components' => [ // ... 'session' => [ 'name' => 'admin_session', 'cookieParams' => [ 'httpOnly' => true, 'path' => '/admin', ], ], ], ];