Backups failing: need to write MySQL unixSocket config to temp my.cnf

[juddlyon]

Description

The _createDumpConfigFile method in /vendor/craftcms/cms/src/db/mysql/Schema.php does not include the unixSocket setting when creating the temporary config file passed to mysqldump via the --defaults-extra-file flag.

When using a non-default socket path this will trigger the following error:

...failed with exit code 2: mysqldump: Got error: 2002: Can't connect to local MySQL server through socket '/tmp/mysql.sock'

I realize there is a backupCommand General Config override, but it feels like if you designate the unixSocket in db.php it should be respected here. The temp file seems to take precedence over my [mysqldump] config so my backups fail.

Here's my quick fix.

$unixSocket = $dbConfig->unixSocket ? 'socket='.$dbConfig->unixSocket : '';
$contents = '[client]'.PHP_EOL.
    'user='.$dbConfig->user.PHP_EOL.
    'password="'.addslashes($dbConfig->password).'"'.PHP_EOL.
    'host='.$dbConfig->server.PHP_EOL.
    'port='.$dbConfig->port.PHP_EOL.
    $unixSocket;

Steps to reproduce

1. Use a non-default unix socket location for MySQL
2. Trigger a backup
3. Check /storage/logs/web.log for the mysqldump error

Additional info

• Craft version: Craft CMS 3.0.2
• PHP version: PHP 7.1.12
• Database driver & version: MySQL 5.6.38
  I'm using the AWS Lightsail Bitnami Nginx 1.12.2-3 AMI where everything is mapped to /opt/bitnami/