title: Google Cloud SQL proxy couldn't find default credentials
body: <p>I'm trying to run Google Cloud SQL proxy locally like this:</p>
  
  <pre><code>$ ./cloud_sql_proxy -instances project-name:region-name:instance-id tcp:3306
  </code></pre>
  
  <p>But it's returning </p>
  
  <pre><code>google: could not find default credentials. See https://developers.google.com/accounts/docs/application-default-credentials for mor information.
  </code></pre>
  
  <p>My Google Cloud SDK is already installed and logged in to Google.</p>
  
  <p>How do I fix this?</p>