Google Cloud Platform Terraform Recipes

At work we’ve recently started to use Terraform to manage the cloud infrastructure of our clients. During my initial research on how to set up a Cloud SQL instance using Terraform, I stumbled upon the “Terraform Google Modules” organization (unaffiliated to Google). They provide several Terraform modules in order to easily create:

  • A Kubernetes Engine Cluster
  • A CloudSQL Instance
  • A CloudSQL HA Cluster (MySQL RR)
  • Cloud Functions
  • Repository Triggers

This will surely save me and my colleagues some work 🙂

Terraform Google Modules (on Terraform Registry) →
Terraform Google Modules (on GitHub) →

Connect to Remote MySQL Server with SSL Certificates from PHP: Fixing the error "Terminated due to signal: ABORT TRAP (6)"


Photo by Clem Onojeghuo on Unsplash

To connect to a MySQL Server that requires SSL from PHP with PDO, you can use this piece of code:

try {
	$db = new PDO('mysql:host=DB_HOST;dbname=DB_NAME', $user, $pass, [
		PDO::MYSQL_ATTR_SSL_KEY => 'path/to/client_private_key',
		PDO::MYSQL_ATTR_SSL_CERT => 'path/to/client_cert',
		PDO::MYSQL_ATTR_SSL_CA => 'path/to/server_ca_cert',
	]);
} catch (PDOException $e) {
	print "Error!: " . $e->getMessage() . "<br/>";
	die();
}

To my surprise I was greeted with an abort signal (not an Exception!) when running this piece of code when trying to connect to a MySQL 5.7 Server on Google Cloud SQL:

Terminated due to signal: ABORT TRAP (6)

Thinking it was a problem with the used certificates I turned to the mysql binary to verify their contents:

$ mysql \
	--ssl-cert='path/to/client_cert' \
	--ssl-key='path/to/client_private_key' \
	--ssl-ca='path/to/server_ca_cert' \
	--host=DB_HOST \
	--user=DB_USERNAME \
	--password

And guess what: that command, of course, worked just fine … but what is the problem then? Is it Google Cloud SQL? Is it PHP acting up?

At the root of the problem is the fact that I’m connecting to the host using an IPv4 address and that the Common Name in the certificate – which one needs to choose manually when generating an SSL Certificate for a Cloud SQL instance – does not match (ref).

To work around this issue you have two options:

  1. (recommended) Connect to your Cloud SQL instance using the Cloud SQL proxy
  2. (not recommended, but needed when solution 1 is not an option) Disable the verification of the server SSL certificate

For the first solution follow Google’s instructions on the Cloud SQL Proxy.

For the second solution, set the PDO::MYSQL_ATTR_SSL_VERIFY_SERVER_CERT option to false:

try {
	$db = new PDO('mysql:host=DB_HOST;dbname=DB_NAME', $user, $pass, [
		PDO::MYSQL_ATTR_SSL_KEY => 'path/to/client_private_key',
		PDO::MYSQL_ATTR_SSL_CERT => 'path/to/client_cert',
		PDO::MYSQL_ATTR_SSL_CA => 'path/to/server_ca_cert',
		PDO::MYSQL_ATTR_SSL_VERIFY_SERVER_CERT => false,
	]);
} catch (PDOException $e) {
	print "Error!: " . $e->getMessage() . "<br/>";
	die();
}

💁‍♂️ Do note that in this case your connection is encrypted, but you’re not validation the server SSL certificate, and therefore cannot be guaranteed that you’re connecting to the correct server …

With all these set, your PHP code should be able to connect to the MySQL instance without being terminated prematurely …

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