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',
],
],
],
];