Last week, Google announced the migration from Vertex AI SDK to Google GenAI SDK. Their official documentation looked comprehensive—until I tried to implement it with service account authentication in production.
The problem? Their migration guide only covers Application Default Credentials (ADC), completely overlooking JSON service accounts—the authentication method most production applications actually use.
After spending hours debugging authentication failures, I realized this wasn’t a “me” problem. It’s a documentation gap that will affect thousands of developers migrating their AI applications.
What I learned:
OAuth2 scope configuration is critical (and not mentioned in their guide)
Python and Go require different approaches for credential management
Google’s scope options for Vertex AI are surprisingly limited (only full access or read-only)
I documented the complete implementation for both Python and Go, including the service account authentication patterns that Google’s guide omits.
Key takeaway: When migrating critical infrastructure, always test authentication flows in staging first. Official documentation isn’t always production-ready.
“Modified by moderator”
Have you encountered similar gaps in cloud migration guides? Let me know in the comments.