Beyond the VPN: Mastering Zero Trust with GCP IAP
The traditional "castle and moat" security model is dead. In the 2026 PCA exam, questions favor Zero Trust architectures that prioritize identity over network location. The star of the show? Identity-Aware Proxy (IAP).
What is Identity-Aware Proxy (IAP)?
IAP is a Google Cloud service that allows you to manage access to applications running on GCP without using a VPN. It uses identity and context (like user location or device health) to determine if a request should be allowed.
Why Architects Love IAP
- No VPN Overhead: Eliminates the performance bottlenecks and licensing costs of traditional VPNs.
- Granular Control: Apply access policies at the application, resource, or even specific URL level.
- Context-Aware Access: Only allow users if they are on a company-managed device or within a specific geography.
- Centralized Management: Manage access across App Engine, Compute Engine, and GKE from one place.
The IAP Workflow
- A user tries to access a protected resource.
- IAP intercepts the request and checks for an Identity Cookie.
- If no cookie exists, IAP redirects the user to Google Accounts for login.
- After login, IAP verifies the user's identity and Access Level (from Access Context Manager).
- If allowed, IAP passes the user's identity to the backend in a JWT (JSON Web Token).
Frequently Asked Questions (FAQ)
Does IAP replace IAM?
No, IAP works alongside IAM. IAP handles the initial authentication and context check, while IAM determines which specific permissions the user has once they are inside the application.
How do I implement IAP for a load balancer?
You enable IAP on the backend service of your Global External HTTP(S) Load Balancer and configure the appropriate IAM roles for the users who need access.
Is IAP free?
IAP is free for most GCP resources like App Engine and GKE. Some advanced context-aware features (via BeyondCorp Enterprise) may carry an additional cost — see our top 10 tips for exam budget logic.
How to implement IAP for EHR?
Enable IAP on the Global Load Balancer to ensure only authorized medical staff on managed devices can access the patient portal — check our EHR Guide.
Does IAP support GKE?
Yes, IAP can be enabled on GKE Ingress to secure containerized applications at the edge — learn more in our Networking Essentials.
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