Example

/**
 *
 */
function myplugin_wpf2b_register()
{
    // Register the plugin
    try {
        do_action(
            'wp_fail2ban_register_plugin',
            'my-plugin-slug',
            'My Plugin Name'
        );
    } catch(\LengthException $e) {
        // slug or name too long
    } catch(\RuntimeException $e) {
        // database error
    }

    // Register a message
    $args = [
        'slug'        => 'my-plugin-msg-slug-1',
        'fail'        => 'hard',
        'priority'    => LOG_NOTICE,
        'event_class' => 'Password',
        'event_id'    => 0x001F,
        'message'     => 'Message with ___VAR1___ and ___VAR2___',
        'vars'        => [
            'VAR1' => '\d+',
            'VAR2' => '*.'
        ]
    ];
    try {
        do_action(
            'wp_fail2ban_register_message',
            'my-plugin-slug',
            $args
        );
    } catch(\InvalidArgumentException $e) {
        // Missing entry or invalid type
    } catch(\UnexpectedValueException $e) {
        // Invalid value
    }
}
add_action(
    'wp_fail2ban_register',
    __NAMESPACE__.'\myplugin_wpf2b_register'
);

/**
 *
 */
function myplugin_foobar()
{
    $vars = [
        'VAR1' => 12345,
        'VAR2' => 'xyz'
    ];
    do_action(
        'wp_fail2ban_log_message',
        'my-plugin-slug',
        'my-plugin-msg-slug-1',
        $vars
    );
}