Using interconnect search-replace wordpress migration tool on Google CloudSQL - wordpress

Question

I recently migrated a site to a new server and am now trying to replace the old domain by the new one using this tool suggested in the wordpress codex.
The SQL instance and the VM are both in the same region and are connected using a cloud sql proxy, however when I try and connect to the database via the searc-replace tool, I get connection refused:
EDIT:
The command used to start the sql proxy is the following:
localhost:/cloudsql/project-name:region:sql-instance-name
It is the same I use in the config file to connect the site to the db.

Answer 1

"Connection Refused" error occurs when an application attempts a TCP connection but there is either no service listening on the target address and port or a firewall rejecting the connection.
First, lets make sure you are connecting on the right port. Run sudo netstat -lntp and look for cloud_sql_proxy. For example you might see
tcp 0 0 127.0.0.1:3306 0.0.0.0:* LISTEN 71313/cloud_sql_pro
indicating cloud sql is listening on port 3306. If you saw this, you should change the port in your tool to 3306.
If netstat does not show any cloud_sql_proxy line, then it isn't listening on TCP. While TCP isn't always needed for MySQL, it looks like the tool your are using does need it. Make sure you start cloud_sql_proxy with -instances=<INSTANCE_CONNECTION_NAME>=tcp:3306
Second, lets make sure you are connecting on the right address. This should be localhost without :/cloudsql/project-name:region:sql-instance-name after.
If it still doesn't work after those two, use sudo iptables -L to look for firewall rules blocking the traffic. I believe it's unlikely that you have a firewall stopping local traffic, however.

Answer 2

An alternative to using the Cloud SQL Proxy is to connect directly to your instance. To do this:
Find the external IP address of the VM you are running the PHP tool on.
Grant access for that IP address to your SQL instance, with the instructions here
Because MySQL can have different username/password depending on where you connect from, ensure there is a username/password combo for host %. instructions here.
Use the tool, with the username/password from (3), port=3306 and host=the IP address of your SQL instance
When you are done, remove access from the IP address to your Cloud SQL instance.