Add comprehensive Kubernetes authentication and authorization documentation

[Copilot]

This PR introduces comprehensive documentation for implementing authentication and authorization in the Fibonacci Kubernetes cluster. The documentation is designed to guide LLM programs through the complete process of securing the cluster with proper RBAC policies, authentication mechanisms, and security best practices.

Overview

The current Fibonacci application deployment lacks proper authentication and authorization controls, with all services running in the default namespace without access restrictions. This documentation provides step-by-step instructions to implement enterprise-grade security.

Documentation Structure

Primary Implementation Guide

• KUBERNETES_AUTH_GUIDE.md - Complete 27,000+ character comprehensive guide covering all aspects of authentication and authorization implementation
• Includes service account setup, RBAC configuration, JWT authentication, network policies, and troubleshooting

Quick Start Resources

• QUICK_AUTH_SETUP.md - Streamlined 15-minute basic setup for immediate security improvements
• TERRAFORM_RBAC_CONFIG.md - Production-ready Infrastructure-as-Code configurations with complete Terraform resources
• AUTH_TESTING_SCRIPTS.md - Comprehensive testing and validation scripts for verifying security implementation

Implementation Roadmap

• AUTH_README.md - Overview document with implementation timeline and success criteria

Security Features Documented

Authentication Methods

• Service Account Authentication - Secure pod-to-pod communication with minimal required permissions
• User Certificate Authentication - X.509 certificate-based user authentication for kubectl access
• JWT Token Authentication - Application-level authentication with role-based access control
• OIDC Integration - Enterprise identity provider integration for production environments

Authorization Roles

• Admin Role (fibonacci-cluster-admin) - Full cluster access including resource creation, deletion, user management, and security policy modification
• Reader Role (fibonacci-cluster-reader) - Read-only access to pods, services, deployments, logs, and monitoring dashboards
• Service Account Roles - Namespace-scoped permissions for each component (Fibonacci app, Prometheus, OpenTelemetry, Grafana)

Security Implementation

• Namespace Isolation - Separation into fibonacci-app, monitoring, and auth-system namespaces
• Network Policies - Traffic control between services and namespaces
• Pod Security Standards - Non-root containers, read-only filesystems, capability dropping
• Secret Management - Secure handling of JWT secrets and OIDC credentials

Architecture Transformation

Before: All services in default namespace without access controls

┌─────────────────────────────────────┐
│           Default Namespace         │
│  Fibonacci + Prometheus + Grafana   │
└─────────────────────────────────────┘

After: Secure, properly segmented architecture

┌─────────────────┐  ┌─────────────────┐  ┌─────────────────┐
│ fibonacci-app   │  │   monitoring    │  │   auth-system   │
│ • JWT Auth      │  │ • Prometheus    │  │ • OIDC Config   │
│ • RBAC Roles    │  │ • Grafana       │  │ • Certificates  │
│ • Network Pol   │  │ • OpenTelemetry │  │ • Secrets       │
└─────────────────┘  └─────────────────┘  └─────────────────┘

Implementation Timeline

The documentation provides multiple implementation paths:

• Quick Setup (15 minutes) - Basic RBAC and authentication
• Terraform Deployment (30 minutes) - Infrastructure-as-code approach
• Complete Implementation (2.5 hours) - Full enterprise security
• Testing & Validation (30 minutes) - Comprehensive verification

Testing & Validation

Includes automated test scripts for:

• RBAC permission validation (test-rbac.sh)
• Authentication mechanism testing (test-authentication.sh)
• Network policy verification (test-network-policies.sh)
• Security compliance checking (validate-security.sh)

This documentation empowers LLM programs to implement robust security measures while maintaining the application's functionality and observability capabilities.

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