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Binoy
Binoy

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Create the Admin Terraform Module and Terraform Admin User

Purpose
This document outlines the architectural decision to create a dedicated Terraform admin module and an admin user, which are responsible for provisioning administrative resources, roles, and users. These components are foundational and will support other Terraform modules across different functional areas.
The key objective is to enable modular, independently deployable infrastructure components that avoid cross-environment impact and align with best practices in security, maintainability, and compliance.

Scope and Context
The Terraform admin module will provision privileged users and roles that are categorized to support the following functional areas:

  • Shared Resources: Networking components such as VPCs, subnets, domains, firewall rules, etc.
  • DevOps Resources: Tools and services needed for development pipelines and deployment operations.
  • Monitoring Resources: Centralized logging, alerting, and observability for management, development, and production environments.
  • Application Environments:
    • Development
    • Production

By segregating users and roles by domain and environment, we reduce the risk of cross-impact between critical systems. For example, changes in the development environment must not affect production.

Security and Compliance Objectives
This approach supports the following best practices and compliance requirements:

  1. Least Privilege Principle
    1. Users and roles are scoped with minimal necessary access, and can be reused across modules responsible for different operational domains.
  2. Maintainability, Testability, and Deployability
    1. Each module can be developed, tested, and deployed in isolation.
  3. Resource Clean-up
    1. Modularization simplifies identifying and removing obsolete or unused resources.
  4. Documentation of Administrative Tasks
    1. Automation replaces manual configuration, ensuring consistency and clarity.
  5. Auditability and Monitoring
    • All administrative activities are captured via cloud audit logs.
    • Role-based access control enforces accountability.
    • Environment separation aids incident analysis and root cause tracing.
    • Enable the log anomaly detection for log review
  6. Single Responsibility and Bounded Context
    • Each module, user, and role has a clearly defined scope and responsibility.

ISO & Regulatory Compliance Alignment
This design supports alignment with ISO/IEC 27001 and 27002 standards, as well as industry benchmarks such as CIS. Specifically:

  • ISO/IEC 27001:
    • ✔️ Segregation of duties (A.6.1.2)
    • ✔️ Access control policy (A.9.1)
    • ✔️ Secure user access management (A.9.2)
    • ✔️ Monitoring and logging (A.12.4, A.12.7)
  • ISO/IEC 27002:
    • ✔️ Emphasis on least privilege, auditability, accountability
    • ✔️ Secure administration of systems and services

Audit capability must cover who, when, where, and which changes—which is addressed by enabling cloud-native audit logging (e.g., CloudTrail, Activity Logs) and alerting on sensitive operations.

Prerequisites

  • Root User Setup
  • Root user should only be used to provision the initial admin-terraform-deployer user and role:
    • User: admin-terraform-deployer
    • Role: admin-terraform-deployer-role
  • Root Usage Mitigation
    • Avoid using the root account in ongoing operations, per CIS security benchmarks.

Admin Module Responsibilities

  • Provision the admin-terraform-deployer user/role.
  • Create and manage the KMS key (admin-terraform-kms-key) for encryption and rotation.
  • Provision the Terraform state GCP bucket bucket with:
    • Versioning enabled (retain last 5 versions)
    • Retention and deletion policies
    • At-rest encryption using admin-terraform-kms-key
    • Separate buckets or folders for dev, prod, and management states
  • Store secrets in a Secrets Manager with encryption using the KMS key
  • Enable Cloud Audit Logging for all admin operations
  • Define a retention policy for logs (e.g., 365 days)
  • Configure alerting and monitoring for:
    • Changes to GCP bucket state files
    • Modifications to the KMS key or key rotations
    • Changes to IAM roles and user privileges

Mitigation Strategies
To address risks and challenges:

  • Maintain clear documentation of:
    • Terraform modules
    • User and role definitions
    • Execution flows and state handling
  • Enforce Terraform state security:
    • Use encrypted remote backends
    • Implement state locking and restricted access policies
  • Implement robust monitoring and alerting
  • Schedule regular security audits to ensure compliance with least privilege principles

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