title: Scaling Cloud SQL instances without cloud_sql_proxy update
body: <p>The issue targets an SQL scaling problem.
  For Cloud SQL Proxy there <a href="https://cloud.google.com/sql/docs/mysql/sql-proxy#instances-options" rel="nofollow noreferrer">are options</a> and one of them is one to specify instances through instance metadata with -instances_metadata option.</p>
  
  <p>Despite -instances flag where we can specify a list of Cloud SQL instances connections names the -instances_metadata flag is not clear how to use.</p>
  
  <p>Is that means that instance metadata works only for SQL instances that are on VMs? Because I don't understand how to add metadata to Cloud SQL Instance or fetch it by some way.</p>
  
  <p>If there is no way to set or rely on Cloud SQL instance metadata that means that there is no way to scale Cloud SQL instances without proxy configuration update. Don't believe it's true. GC should support that.</p>
  
  <p>Thank you for any advice.</p>