Step-by-step instruction
Step 1
At the root of the project (@app) add a .htaccess with the following content:
<IfModule mod_rewrite.c>
Options +FollowSymlinks
RewriteEngine On
</IfModule>
<IfModule mod_rewrite.c>
RewriteCond %{REQUEST_URI} ^/(admin)
RewriteRule ^admin/assets/(.*)$ backend/web/assets/$1 [L]
RewriteRule ^admin/css/(.*)$ backend/web/css/$1 [L]
RewriteRule ^admin/js/(.*)$ backend/web/js/$1 [L]
RewriteCond %{REQUEST_URI} !^/backend/web/(assets|js|css|js)/
RewriteCond %{REQUEST_URI} ^/(admin)
RewriteRule ^.*$ backend/web/index.php [L]
RewriteCond %{REQUEST_URI} ^/(assets|css|js|images)
RewriteRule ^assets/(.*)$ frontend/web/assets/$1 [L]
RewriteRule ^css/(.*)$ frontend/web/css/$1 [L]
RewriteRule ^js/(.*)$ frontend/web/js/$1 [L]
RewriteRule ^images/(.*)$ frontend/web/images/$1 [L]
RewriteRule ^(.*)$ frontend/web/$1 [L]
RewriteCond %{REQUEST_URI} !^/(frontend|backend)/web/(assets|css|js)/
RewriteCond %{REQUEST_URI} !index.php
RewriteCond %{REQUEST_FILENAME} !-f [OR]
RewriteCond %{REQUEST_FILENAME} !-d
RewriteRule ^.*$ frontend/web/index.php
</IfModule>
Where admin - path to the @backend/web.
Step 2
In the folder @frontend/web add the file .htaccess with the following content:
RewriteEngine on
# if a directory or a file exists, use it directly
RewriteCond %{REQUEST_FILENAME} !-f
RewriteCond %{REQUEST_FILENAME} !-d
# otherwise forward it to index.php
RewriteRule . index.php
Step 3
In the file @frontend/config/main.php in item components of array add:
'request' => [
'baseUrl' => '',
],
'urlManager' => [
'enablePrettyUrl' => true,
'showScriptName' => false,
'rules' => [
'' => 'site/index',
'<controller:\w+>/<action:\w+>/' => '<controller>/<action>',
],
],
Step 4
In the folder @backend/web add the file .htaccess with the following content:
RewriteEngine on
# if a directory or a file exists, use it directly
RewriteCond %{REQUEST_FILENAME} !-f
RewriteCond %{REQUEST_FILENAME} !-d
# otherwise forward it to index.phpp
RewriteRule . index.php
Step 5
In the file @backend/config/main.php in item components of array add:
'request' => [
'baseUrl' => '/admin',
],
'urlManager' => [
'enablePrettyUrl' => true,
'showScriptName' => false,
'rules' => [
'' => 'site/index',
'<controller:\w+>/<action:\w+>/' => '<controller>/<action>',
],
],
Well done)