I'm trying to get "data in transit" via SSL between Drupal 7 to RDS Mysql. I've confirmed the following:

* SSL is configured by default in all Mysql RDS instances.
* The Mysql instance I have brought up can be connected to using Mysql client using the following command:

mysql --ssl-ca=/path/to/ssl-cert  --user=USERID --host=HOSTNAME -p

I've also added a Require SSL directive for this user I am trying to connect as:

GRANT USAGE ON *.* TO 'USERNAME'@'%' REQUIRE SSL
GRANT USAGE ON *.* TO 'USERNAME'localhost'%' REQUIRE SSL

I've confirmed (using the above command) that this user can login if the --ssl-ca argument is passed, but cannot login without it.

I then started digging in to determine how to configure Drupal 7 to have it connect to Mysql using SSL. I found this post

This post implies quite strongly that this support should now be configurable. I've confirmed that the version of Drupal I'm using does have this patch applied. What I cannot seem to find or figure out is exactly how I turn SSL support on for the connection. I've tried the following configurations for my databases array:

$databases = array (
  'default' =>
  array (
    'default' =>
    array (
      'database' => 'DBNAME',
      'username' => 'USERNAME',
      'password' => 'PASSWORD',
      'host' => 'HOSTNAME',
      'port' => '',
      'driver' => 'mysql',
      'prefix' => '',
      'ssl-ca' => 'ssl-ca=/path/to/ssl-cert',
    ),
  ),
);

// Other versions that don't work
'ssl-ca' => '/path/to/ssl-cert',

'init_commands' => array(
  'ssl-ca' => 'ssl-ca=/path/to/ssl-cert',
),

'init_commands' => array(
  'ssl-ca' => 'ssl-ca=/path/to/ssl-cert',
),

'init_commands' => array(
  'ssl-ca' => 'set MYSQL_ATTR_SSL_CA=/path/to/ssl-cert',
),

In each case, the database authentication fails. Note: I have confirmed that this same databases array works when I turn off REQUIRES SSL in the database.

Has anyone gotten this to work?