In Google Cloud, Identity and Access Management (IAM) helps you maintain access control over your cloud resources and operations. While it includes other features, this is its primary purpose. If you ever tried to harden security over your application, you know the importance of the Principle of Least Privilege (PoLP) ‒ grant the absolute minimum permissions to your users and workloads to allow them to perform their tasks. You reach it through use of predefined roles and custom roles and setting up a combination of Allow and Deny IAM policies at project, folder, or organization level. Using a combination of Allow and Deny policies along the resource hierarchy is an effective way to control access. This approach lets you enforce PoLP across many different scenarios.
The existing flexible control can be insufficient when resources in the project are shared between multiple workloads or used by more than one team. In many such scenarios, it is possible to bind IAM policies to a specific resource in the project. For example, consider the difference between granting the role Artifact Registry Editor (roles/artifactregistry.editor) on a project vs. granting it on a specific repository in the project. In the former case, the access is granted to ANY repository in the project. In the latter case, users will have the editor access only to a specific repository. However, binding IAM policies to a resource or service level isn’t always possible. This is when it is time to use IAM conditions. Let’s look at two distinct examples that demonstrate the power of conditions when hardening access management: one for traditional administrative roles, and one for modern AI integrations.
Use Case 1: Constraining the Power of Admins
This case demonstrates how to restrict the specific operations that broad IAM roles are authorized to perform. You can easily scope administrative privileges for managing specific resources in a project by granting a “resource creator” role at the project level and an editor role on a selected resource. It is far more challenging to constrain IAM Admin Roles that are intended to grant access to operations rather than specific resources. A representative example would be the IAM Admin role (roles/iam.admin). Users granted this role can grant themselves any other role or create a new one. It greatly exceeds practical needs. The first step is to narrow the access by using the Project IAM Admin role (roles/resourcemanager.projectIamAdmin) that provides administrative privileges only at the level of the project.
It is possible, however, to restrict the granted privileges even further. For example, suppose you grant the Project IAM Admin role to your builder service account that creates resources and deploys workloads. The workloads only need access to the BigQuery and Agent Platform APIs (formerly Vertex APIs) and permission to write logs and traces. For such a case you can use the following gcloud CLI command or its alternative in Terraform:
