Azure to Vertex AI Authentication

Disclaimer

This specific page uses temporary drafts written and maintained by Generative AI. While verified to be accurate, please cross-verify with source code.

TomoriBot runs on an Azure VM but can call Google Vertex AI without storing a Google service account key. Production uses Google Cloud Workload Identity Federation (WIF) and the Azure VM’s system-assigned managed identity.

Production identity flow

1. TomoriBot reads the non-secret external-account configuration from /run/secrets/google-vertex-wif.json.
2. Google Auth obtains a managed identity token from Azure Instance Metadata Service (IMDS).
3. Google Security Token Service accepts that token only when its xms_mirid claim matches the production VM resource ID.
4. The federated principal impersonates [email protected].
5. That service account calls Vertex AI in the tomoribot-vertex project.

No Google private key or API key is stored on the VM. The checked-in deploy/azure/google-vertex-wif.json file contains only public federation metadata.

Google Cloud boundary

• Project ID: tomoribot-vertex
• Project purpose: Vertex AI provider calls only; it does not host TomoriBot infrastructure
• Workload identity pool/provider: tomoribot-azure/azure-vm
• Runtime service account roles: Vertex AI User and Service Usage Consumer
• Service account binding: Workload Identity User for principals admitted by the pool
• Provider condition: exact Azure production VM resource ID (xms_mirid)

The Azure VM must retain its system-assigned identity. Terraform declares this in terraform/azure/vm.tf so a future apply does not remove it.

Deployment

The Azure deployment workflow installs the federation file at /etc/tomoribot/google-vertex-wif.json with owner root, group ID 1001, and mode 0640. Docker Compose mounts it read-only and sets GOOGLE_APPLICATION_CREDENTIALS to the container path. Treat write access to the host copy as privileged even though the file is not a secret: changing its audience or impersonation target changes the identity TomoriBot requests.

Discord configuration

Run /provider add, choose Google Vertex AI, and enter:

tomoribot-vertex::global

The saved value is the Google project and location, not a credential. The Azure workload identity provides the credential at runtime. Google Vertex AI Express is a separate API-key provider and does not use this path.

Verification

After deployment, verify that the container is healthy, the credential file is mounted read-only, and a small Vertex request succeeds. countTokens is suitable for an authentication smoke test because it exercises ADC, federation, service-account impersonation, and the Vertex endpoint without generating a model response.

Billing budgets and alerts are monitoring controls, not hard spending caps. Keep this project free of unrelated resources so its billing activity is attributable to Vertex usage.