Feature Request: Support regulated and non-regulated multi-tenancy within a single GCP Organization #387

Summary

Enable Stellar Engine to support mixed-compliance multi-tenancy (regulated and non-regulated environments) within a single Google Cloud Organization, without requiring separate Google Cloud Organizations per compliance tier.

Problem Statement

Many public-sector, higher-education, and research institutions operate under a single centralized Google Cloud Organization (tied to one primary identity domain) while running two distinct classes of workloads side by side:

1. Regulated workloads requiring Assured Workloads compliance boundaries and strict controls (for example, HIPAA, FedRAMP Moderate/High, or DoD IL4/IL5 enclaves with mandatory CMEK, regional restrictions, and dedicated Shared VPC inspection).
2. Non-regulated workloads (for example, general academic research, open collaboration, or burst HPC/AI compute across multiple regions) where organization-wide Assured Workloads constraints, single-region lock-in, or mandatory CMEK create unnecessary operational friction and cost.

Today, Stellar Engine (fast/stages-aw/*) assumes a centralized, single-regime Organization deployment:

• 0-bootstrap binds directly to the root organization (setIAM.sh, organization-level log_sinks, and org_policies_config) and configures a single global assured_workloads regime and location.
• 1-resman provisions tenants that all inherit the same centralized Stage 0 / Stage 2 compliance controls and network perimeter.
• 3-security enforces uniform security constraints (such as gcp.restrictNonCmekServices and gcp.restrictCmekCryptoKeyProjects).

As a result, organizations needing both regulated (e.g., HIPAA) and non-regulated tenants must currently either:

• Stand up two separate Google Cloud Organizations (duplicating identity federation, billing setup, and two full Stellar Engine deployments), or
• Bypass Stellar Engine in favor of upstream Cloud Foundation Fabric (FAST) and manually layer Assured Workloads folders on top.

Proposed Solution

Support isolated multi-tenancy across regulated and non-regulated boundaries within one Google Cloud Organization through either (or both) of the following patterns:

1. Folder-Scoped (Sub-Org Enclave) Deployment Mode:
   • Allow 0-bootstrap and downstream stages (1-resman, 2-networking-*, 3-security) to target a designated parent Folder ID rather than requiring exclusive root Organization ownership, so one or more regulated Stellar Engine enclaves can coexist alongside non-regulated folders/stages in the same Organization.
2. Per-Tenant / Per-Enclave Compliance Tiers in 1-resman, 2-networking, and 3-security:
   • Allow tenants (or tenant groups/folders) in 1-resman to specify distinct compliance profiles—e.g., provisioning Assured Workloads folders and scoped Organization Policies/Shared VPCs/CMEK only on regulated tenant folders while permitting standard non-regulated tenant folders under the same Stage 0 administrative foundation.

Additional Context

Supporting coexisting regulated and non-regulated tenants under a single Organization aligns Stellar Engine with upstream Cloud Foundation Fabric (FAST) flexibility while preserving Stellar Engine's compliance automation and NIST SP 800-53 control mappings for the regulated enclaves that require them.