Laravel failing to connect to DB after 4.2 upgrade - mysql

Question

I just upgraded my Laravel install from 4.1.(something) to 4.2.7 using the steps recommended here: http://laravel.com/docs/upgrade
Now I'm getting this error on every page:
PDOException (2002)
SQLSTATE[HY000] [2002] Can't connect to local MySQL server through socket '' (111)
MySQL is not running locally, but it's not supposed to be. I don't have any configuration for connecting to local MySQL, my development SQL server is remote. Why is it trying to connect to local?
Is there some config change that isn't mentioned in the upgrade guide? Everything was peachy in 4.1.
From my app/config/database.php file:
'default' => 'mysql',
...
'connections' => array(
'mysql' => array(
'driver' => 'mysql',
'host' => 'myrealdb.us-east-1.rds.amazonaws.com',
'database' => 'myrealdbname',
'username' => 'myrealuser',
'password' => 'myrealpass',
'charset' => 'utf8',
'collation' => 'utf8_unicode_ci',
'prefix' => '',
'database_port' => '3306',
'unix_socket' => '',
),
...
);
I tried php artisan clear-compiled and php artisan dump-autoload just in case. No effect.

Answer 1

Edit: I submitted a fix for this that has been merged into the 4.2 branch. You shouldn't have to worry about this error anymore.
I got it! This appears to be a change in the way Laravel uses the database configuration, I hope this answer helps others.
The short version is: if your connection is configured like mine (in the question), delete the unix_socket entry from the array.
Previously, I always copied and edited the default entries in the connections array, leaving in the unix_socket parameter as empty. Apparently now there's a check that assumes if unix_socket is present, it should use a socket DSN string. The empty string in my config passed the check. You can see how this happens in /vendor/laravel/framework/src/Illuminate/Database/Connectors/MySqlConnector.php. The functions getDsn, getSocketDsn, and getHostDsn tell the story.
Pasted because this will eventually change:
protected function getDsn(array $config)
{
return isset($config['unix_socket']) ? $this->getSocketDsn($config) : $this->getHostDsn($config);
}
...
protected function getSocketDsn(array $config)
{
extract($config);
return "mysql:unix_socket={$config['unix_socket']};dbname={$database}";
}
...
protected function getHostDsn(array $config)
{
extract($config);
return isset($config['port'])
? "mysql:host={$host};port={$port};dbname={$database}"
: "mysql:host={$host};dbname={$database}";
}