Quickstart: using the Google Cloud Console
This page shows you how to perform basic tasks in Pub/Sub using the Google Cloud Console.
Note: If you are new to Pub/Sub, we recommend that you start with the interactive tutorial.
Before you begin
Set up a Cloud Console project.
Set up a project
Click to:
Create or select a project.
Enable the Pub/Sub API for that project.
You can view and manage these resources at any time in the Cloud Console.
Install and initialize the Cloud SDK.
Note: You can run the gcloud tool in the Cloud Console without installing the Cloud SDK. To run the gcloud tool in the Cloud Console, use Cloud Shell .
https://cloud.google.com/pubsub/docs/quickstart-console

The requirement is for an infrastructure-as-code (IaC) solution that can manage Kubernetes resources and other cloud resources across multiple cloud providers (Google Cloud and two others).
Option A (YAML manifests): YAML manifests are primarily used for defining Kubernetes objects, not for provisioning general cloud resources (like VPCs, IAM policies, databases) across different cloud providers.
Option C (Python + SDKs): While possible, writing custom scripts using each provider's SDK requires significant development effort to handle state management, dependencies, and provider differences. It essentially reinvents much of what dedicated IaC tools provide and is not a standard IaC approach.
Option D (Config Connector): Config Connector allows managing Google Cloud resources using Kubernetes- style manifests and APIs. It is specific to Google Cloud and cannot manage resources in other cloud providers.
Option B (Terraform): Terraform is an open-source IaC tool explicitly designed for building, changing, and versioning infrastructure safely and efficiently across multiple cloud providers and on-premises data centers.
It uses providers for different platforms (GCP, AWS, Azure, Kubernetes, etc.), allowing a unified workflow to manage diverse resources across the required environments (Google Cloud, other clouds, Kubernetes).
Terraform is the standard tool for multi-cloud IaC automation as described in the scenario.
References:
Terraform on Google Cloud: "Terraform is an open source infrastructure as code (IaC) tool... Terraform lets you manage Google Cloud resources with declarative configuration files..." - https://cloud.google.com/docs
/terraform
Terraform Providers (General): Terraform supports numerous providers for various cloud platforms and services. - https://registry.terraform.io/browse/providers Config Connector Overview: "Config Connector is a Kubernetes addon that allows you to manage Google Cloud resources through Kubernetes." (Google Cloud specific) - https://cloud.google.com/config-connector
/docs/overview

Let ' s analyze each option to find the one that meets the requirements of no startup time for new traffic, two idle instances, and minimal administrative overhead:
A). Unchecking " Serve this revision immediately " and using a traffic simulation tool: Unchecking " Serve this revision immediately " does prevent the new revision from receiving traffic immediately. However, manually using a traffic simulation tool adds administrative overhead. It also doesn ' t guarantee that two idle instances will be ready before traffic is shifted; you would need to monitor and adjust traffic manually based on the simulation.
B). Configuring service autoscaling and setting the minimum number of instances to 2: Service-level autoscaling applies to all revisions of the service. Setting the minimum instances at the service level would ensure at least two instances are running across all active revisions, not specifically for the new revision before traffic shift.
C). Configuring revision autoscaling for the new revision and setting the minimum number of instances to 2:
This is the correct approach. By configuring revision autoscaling specifically for the new revision and setting the minimum number of instances to 2, Cloud Run will ensure that at least two instances of the new version are running and ready to serve traffic before you redirect any traffic to it. This eliminates startup latency when you do shift traffic. It also minimizes administrative overhead as Cloud Run manages the instance scaling based on this configuration.
D). Configuring revision autoscaling for the existing revision and setting the minimum number of instances to
2: This would ensure the existing version has at least two idle instances, which doesn ' t directly address the requirement of having idle instances ready for the new version before traffic redirection.
Google Cloud Documentation References:
Cloud Run Autoscaling: https://cloud.google.com/run/docs/configuring/min-instances - This document explains how to configure minimum and maximum instances for Cloud Run services and revisions. It clarifies that you can set minimum instances at the revision level to ensure instances are always ready.
Cloud Run Traffic Management: https://cloud.google.com/run/docs/managing/traffic - This describes how to deploy new revisions and gradually shift traffic between them. Combining minimum instances on the new revision with traffic splitting allows for zero-downtime deployments with pre-warmed instances.

https://cloud.google.com/architecture/identity/migrating-consumer-accounts