Support caching_sha2_password authentication plugin with Proxy in Unix Socket mode

[jackwotherspoon]

The Cloud SQL Proxy currently does not support the caching_sha2_password authentication plugin when listening over a unix socket.

This is an issue as in MySQL 8.4, caching_sha2_password has now become the default authentication plugin. Any new database users created with the caching_sha2_password will be unable to log in via the Proxy over unix socket.

Failed logins are not always clear that the authentication plugin is the root cause of the issue:

ERROR 1045 (28000): Access denied for user 'my-user'@'cloudsqlproxy~34.124.164.49' (using password: YES)

The Cloud SQL Language Connectors are a viable alternative and workaround at the moment as they work with MySQL 8.4 and the caching_sha2_password plugin:

• Cloud SQL Go connector
• Cloud SQL Java connector
• Cloud SQL Python connector
• Cloud SQL Node.js connector