Change audit log to JSON format in Percona Mysql - mysql

Question

How to modify the system variable audit_log_format to change to JSON format. The variable is read-only and cannot be changed when the server is running.
mysql> SHOW variables LIKE 'audit%';
+-----------------------------+---------------+
| Variable_name | Value |
+-----------------------------+---------------+
| audit_log_buffer_size | 1048576 |
| audit_log_exclude_accounts | |
| audit_log_exclude_commands | |
| audit_log_exclude_databases | |
| audit_log_file | audit.log |
| audit_log_flush | OFF |
| audit_log_format | OLD |
| audit_log_handler | FILE |
| audit_log_include_accounts | |
| audit_log_include_commands | |
| audit_log_include_databases | |
| audit_log_policy | ALL |
| audit_log_rotate_on_size | 0 |
| audit_log_rotations | 0 |
| audit_log_strategy | ASYNCHRONOUS |
| audit_log_syslog_facility | LOG_USER |
| audit_log_syslog_ident | percona-audit |
| audit_log_syslog_priority | LOG_INFO |
+-----------------------------+---------------+
18 rows in set (0.00 sec)
I edit my my.cnf in this way, but it doesnt work
bash-4.4$ cat ./etc/my.cnf
#
# The Percona Server 5.7 configuration file.
#
#
# * IMPORTANT: Additional settings that can override those from this file!
# The files must end with '.cnf', otherwise they'll be ignored.
# Please make any edits and changes to the appropriate sectional files
# included below.
#
!includedir /etc/my.cnf.d/
!includedir /etc/percona-server.conf.d/
[mysqld]
## Audit Logging ##
audit_log_format=JSON

Answer 1

The audit plugin is need to be loaded at first.
[mysqld]
plugin-load="audit_log=audit_log.so"
audit_log_policy=ALL
audit_log_format=JSON
audit_log_rotate_on_size=1024M
audit_log_rotations=10