how to achieve an apache Alias with a proxy pass on the same domain
You have to combine both:
<VirtualHost *:80> ServerName domain.org ServerAlias www.domain.org ProxyPass /blog ! Alias /blog /var/apache-vhosts/www.domain.org-blog <Directory /var/apache-vhosts/www.domain.org-blog/> Options Indexes FollowSymLinks MultiViews AllowOverride All Order allow,deny allow from all </Directory> ErrorLog ${APACHE_LOG_DIR}/error.log # Possible values include: debug, info, notice, warn, error, crit, # alert, emerg. LogLevel warn CustomLog ${APACHE_LOG_DIR}/access.log combined ProxyPass / http://localhost:8884/ ProxyPassReverse / http://localhost:8884/ ProxyPreserveHost on LogLevel debug</VirtualHost>