Give permission to a file when making a queries log (queries) in mysql

I try to make a mysql querys log in ubuntu and do the following (recommended for mysql 5.6+, which is the version I have):

[mysqld]
general_log = on
general_log_file=/var/log/apache2/mysql-query.log

in my my.cnf file.

When I restart the mysql service I do tests and the queries are not stored in the path that I specified. The file has 666 permissions and the owner left it in the following way:

sudo chown mysql:mysql /var/log/apache2/mysql-query.log

Then I enter mysql from the console and manually execute what I put in my my.cnf file.

 SET GLOBAL general_log = 'ON';

and I get the following error:

  

ERROR 29 (HY000): File '/var/log/apache2/mysql-query.log' not found (Errcode: 13 - Permission denied)

Why? It is assumed that the file already has permissions. I need help.