Allowing Wordpress to update/install with SSH Keys

You have two options to bypass FTP.

1. First one is using Direct write to wp-content directory

This method doesn’t require FRP or SSH, it directly writes to wp-content directory. You must ensure before using this method that you does have sufficient permissions to write to wp-content. Usually you would go with setting ownership to regular user (e.g. sammy) and group to apache (apache is CentOS equivalent to Ubuntu’s www-data).

This is done by following command:

sudo chown -R sammy:apache /var/www/html

After you make sure it is setup correctly you will have to change wp-config.php. Find FS_METHOD and change its value to direct. It should look like -> define('FS_METHOD', 'direct);

2. First one is using SSH/SFTP write to wp-content directory

There is How To Configure Secure Updates and Installations in WordPress on Ubuntu by DigitalOcean. It is for older version but it still should do its job. Keep in mind if you are using php7 to use equivalent packages for it.