Blue-Green Deployments for GCP Managed Instance Groups with Harness

Feb 5, 2026

Learn how to set up and execute zero-downtime blue-green deployments for Google Cloud Managed Instance Groups (MIG) using Harness Continuous Delivery.

In this demo, we cover:

  • What is a Managed Instance Group (MIG)
  • Understanding Blue-Green deployment strategy
  • Prerequisites for MIG blue-green deployment
  • Configuring the Harness pipeline (Service, Environment, Infrastructure)
  • First deployment – automatic creation of secondary MIG and backend service
  • Second deployment – traffic shifting between stable and stage environments
  • How Harness handles labeling, state management, and rollback
  • For more info, refer to Harness docs: https://developer.harness.io/docs/continuous-delivery/deploy-srv-diff-platforms/google-cloud-functions/mig