Implement ResourceCapsule CRD and Operator with GitOps support

[Copilot]

This PR implements a complete Kubernetes Custom Resource Definition (CRD) and operator solution for ResourceCapsules, extending the existing basic-docker-engine with native Kubernetes integration and GitOps workflow support.

🚀 Key Features Implemented

ResourceCapsule CRD

• Complete OpenAPI v3 schema with validation constraints for data integrity
• Namespace-scoped resources supporting multi-tenant environments
• Status subresource for proper lifecycle management (Pending, Active, Failed)
• Built-in rollback configuration with previous version tracking

Operator Implementation

• Event-driven controller that watches ResourceCapsule Add/Modify/Delete events
• Automated resource creation - creates ConfigMaps or Secrets based on spec
• Status management with timestamps and descriptive messages
• Graceful error handling and recovery mechanisms

CLI Integration

New k8s-crd command suite providing:

# Create ResourceCapsule from file
basic-docker k8s-crd create app-config 1.0 /path/config.yaml [configmap|secret]

# List all ResourceCapsules
basic-docker k8s-crd list

# Get ResourceCapsule details
basic-docker k8s-crd get app-config

# Delete ResourceCapsule
basic-docker k8s-crd delete app-config

# Rollback to previous version
basic-docker k8s-crd rollback app-config 0.9

# Start the operator
basic-docker k8s-crd operator start [namespace]

GitOps Ready

• Declarative YAML configuration for version control integration
• ArgoCD/Flux compatible - works with popular GitOps tools
• Built-in versioning with automated rollback capabilities
• Kubernetes-native resource management

🔧 Technical Implementation

Core Components

• crd_types.go - Go structs with full DeepCopy support for CRD API
• crd_operator.go - ResourceCapsule operator with event handling
• k8s/crd-resourcecapsule.yaml - CRD definition with OpenAPI schema
• Updated kubernetes.go with dynamic client and CRD management functions

Testing & Validation

• Unit tests for CRD types, DeepCopy operations, and unstructured handling
• Integration tests added to kind workflow for real cluster validation
• Error handling tests for graceful degradation in test environments
• Demo script (demo-crd.sh) showcasing end-to-end functionality

Example Usage

apiVersion: capsules.docker.io/v1
kind: ResourceCapsule
metadata:
  name: app-config
spec:
  data:
    config.yaml: |
      database:
        host: db.example.com
        port: 5432
      redis:
        host: redis.example.com
  version: "1.0"
  capsuleType: configmap
  rollback:
    enabled: true
status:
  phase: Active
  lastUpdated: "2024-08-02T12:00:00Z"
  message: "ResourceCapsule successfully created"

🎯 Benefits

1. Native Kubernetes Integration - ResourceCapsules are now first-class Kubernetes resources
2. Operator Pattern - Automated lifecycle management following Kubernetes best practices
3. GitOps Compatible - Declarative configuration enables GitOps workflows
4. Backward Compatible - Existing k8s-capsule commands remain unchanged
5. Production Ready - Comprehensive testing and error handling

📋 Files Modified/Added

• ✅ k8s/crd-resourcecapsule.yaml - CRD definition
• ✅ crd_types.go - Go API types for ResourceCapsule CRD
• ✅ crd_operator.go - ResourceCapsule operator implementation
• ✅ crd_test.go - Tests for CRD functionality
• ✅ kubernetes.go - Added CRD management functions
• ✅ main.go - Added k8s-crd CLI commands
• ✅ .github/workflows/kind.yml - Updated with CRD testing
• ✅ KUBERNETES_INTEGRATION.md - Updated documentation
• ✅ demo-crd.sh - End-to-end demonstration script

This implementation addresses all requirements from the issue: CRD implementation, operator functionality, automated versioning, rollback capabilities, and GitOps integration, while maintaining pragmatic decisions and minimal complexity.

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