Feature Request: Add IPv6 subnet support for ENI attachments

## Summary

Add comprehensive IPv6 subnet support to the AWS Multi-ENI Controller, enabling IPv6-only and dual-stack (IPv4 + IPv6) ENI configurations through NodeENI resources.

## Motivation

As AWS VPCs increasingly adopt IPv6 for modern cloud-native applications, the AWS Multi-ENI Controller needs to support IPv6 subnets to remain relevant for next-generation networking requirements. This includes support for IPv6-only environments and dual-stack configurations that many enterprises are adopting.

## Feature Description

### Core Functionality

- **IPv6 Subnet Support**: Ability to specify IPv6 subnet IDs in NodeENI resource specifications
- **Dual-Stack Configuration**: Support for both IPv4 and IPv6 subnets in a single NodeENI resource
- **IPv6 Address Management**: Automatic IPv6 address assignment and management for attached ENIs
- **AWS VPC Integration**: Full integration with AWS VPC IPv6 functionality and routing
- **Status Reporting**: Enhanced ENI attachment status to include IPv6 addresses and subnet information
- **Multus CNI Compatibility**: Ensure seamless integration with existing Multus CNI configurations
- **SR-IOV/DPDK Compatibility**: Maintain compatibility with existing SR-IOV and DPDK functionality

### Proposed NodeENI Resource Schema

```yaml
apiVersion: networking.k8s.aws/v1alpha1
kind: NodeENI
metadata:
  name: dual-stack-eni
spec:
  nodeSelector:
    ng: ipv6-enabled
  
  # IPv4 Configuration (existing)
  subnetIDs:
    - subnet-12345678  # IPv4 subnet
  
  # NEW: IPv6 Configuration
  ipv6SubnetIDs:
    - subnet-ipv6-abcdef123  # IPv6 subnet
  
  # Alternative: Combined subnet configuration
  # subnets:
  #   - id: subnet-12345678
  #     type: ipv4
  #   - id: subnet-ipv6-abcdef123
  #     type: ipv6
  
  securityGroupIDs:
    - sg-12345678
  deviceIndex: 2
  
  # IPv6-specific configuration
  ipv6Config:
    enabled: true
    addressCount: 1  # Number of IPv6 addresses to assign
    prefixDelegation: false  # Enable IPv6 prefix delegation
    
status:
  attachments:
    - eniID: eni-12345678
      deviceIndex: 2
      status: attached
      # IPv4 information (existing)
      subnetID: subnet-12345678
      subnetCIDR: "10.0.1.0/24"
      privateIPAddress: "10.0.1.100"
      # NEW: IPv6 information
      ipv6SubnetID: subnet-ipv6-abcdef123
      ipv6SubnetCIDR: "2001:db8::/64"
      ipv6Addresses:
        - "2001:db8::100"
        - "2001:db8::101"
      lastUpdated: "2025-05-28T10:00:00Z"
```

### Example Configurations

#### 1. IPv6-Only ENI
```yaml
apiVersion: networking.k8s.aws/v1alpha1
kind: NodeENI
metadata:
  name: ipv6-only-eni
spec:
  nodeSelector:
    workload: ipv6-native
  ipv6SubnetIDs:
    - subnet-ipv6-123456
  securityGroupIDs:
    - sg-ipv6-789012
  deviceIndex: 2
  ipv6Config:
    enabled: true
    addressCount: 2
```

#### 2. Dual-Stack ENI (IPv4 + IPv6)
```yaml
apiVersion: networking.k8s.aws/v1alpha1
kind: NodeENI
metadata:
  name: dual-stack-eni
spec:
  nodeSelector:
    network: dual-stack
  subnetIDs:
    - subnet-ipv4-abc123  # IPv4 subnet
  ipv6SubnetIDs:
    - subnet-ipv6-def456  # IPv6 subnet
  securityGroupIDs:
    - sg-dual-stack-789
  deviceIndex: 3
  ipv6Config:
    enabled: true
    addressCount: 1
```

#### 3. IPv6 with SR-IOV (Non-DPDK)
```yaml
apiVersion: networking.k8s.aws/v1alpha1
kind: NodeENI
metadata:
  name: ipv6-sriov-eni
spec:
  nodeSelector:
    workload: high-performance-ipv6
  ipv6SubnetIDs:
    - subnet-ipv6-sriov-123
  securityGroupIDs:
    - sg-sriov-ipv6-456
  deviceIndex: 2
  # SR-IOV Configuration
  enableDPDK: false
  dpdkPCIAddress: "0000:00:07.0"
  dpdkResourceName: "intel.com/sriov_ipv6_kernel"
  # IPv6 Configuration
  ipv6Config:
    enabled: true
    addressCount: 1
```

#### 4. IPv6 with DPDK
```yaml
apiVersion: networking.k8s.aws/v1alpha1
kind: NodeENI
metadata:
  name: ipv6-dpdk-eni
spec:
  nodeSelector:
    workload: dpdk-ipv6
  ipv6SubnetIDs:
    - subnet-ipv6-dpdk-789
  securityGroupIDs:
    - sg-dpdk-ipv6-012
  deviceIndex: 4
  # DPDK Configuration
  enableDPDK: true
  dpdkDriver: "vfio-pci"
  dpdkPCIAddress: "0000:00:08.0"
  dpdkResourceName: "intel.com/sriov_dpdk_ipv6"
  # IPv6 Configuration
  ipv6Config:
    enabled: true
    addressCount: 2
```

#### 5. Multus CNI NetworkAttachmentDefinition for IPv6
```yaml
apiVersion: "k8s.cni.cncf.io/v1"
kind: NetworkAttachmentDefinition
metadata:
  name: ipv6-secondary-network
  namespace: default
spec:
  config: '{
    "cniVersion": "0.3.1",
    "type": "ipvlan",
    "master": "eth2",
    "mode": "l2",
    "ipam": {
      "type": "static",
      "addresses": [
        {
          "address": "2001:db8::100/64",
          "gateway": "2001:db8::1"
        }
      ],
      "routes": [
        {
          "dst": "::/0",
          "gw": "2001:db8::1"
        }
      ]
    }
  }'
```

## Implementation Approach

### 1. NodeENI CRD Updates
```go
// Proposed Go structures
type NodeENISpec struct {
    // Existing fields...
    SubnetIDs         []string `json:"subnetIDs,omitempty"`
    
    // NEW: IPv6 support
    IPv6SubnetIDs     []string     `json:"ipv6SubnetIDs,omitempty"`
    IPv6Config        *IPv6Config  `json:"ipv6Config,omitempty"`
    
    // Alternative: Unified subnet configuration
    // Subnets []SubnetConfig `json:"subnets,omitempty"`
}

type IPv6Config struct {
    Enabled           bool  `json:"enabled"`
    AddressCount      int32 `json:"addressCount,omitempty"`
    PrefixDelegation  bool  `json:"prefixDelegation,omitempty"`
}

type ENIAttachment struct {
    // Existing IPv4 fields...
    ENIID            string `json:"eniID"`
    SubnetID         string `json:"subnetID"`
    SubnetCIDR       string `json:"subnetCIDR"`
    PrivateIPAddress string `json:"privateIPAddress"`
    
    // NEW: IPv6 fields
    IPv6SubnetID     string   `json:"ipv6SubnetID,omitempty"`
    IPv6SubnetCIDR   string   `json:"ipv6SubnetCIDR,omitempty"`
    IPv6Addresses    []string `json:"ipv6Addresses,omitempty"`
}

// Alternative unified approach
type SubnetConfig struct {
    ID   string `json:"id"`
    Type string `json:"type"` // "ipv4" or "ipv6"
}
```

### 2. AWS EC2 Client Enhancement
- Extend EC2 client to support IPv6 subnet operations
- Add IPv6 address assignment and management
- Implement IPv6 subnet validation and discovery
- Support for dual-stack ENI creation and configuration

### 3. ENI Manager Updates
- Update interface configuration logic for IPv6
- Add IPv6 routing and address management
- Ensure IPv6 compatibility with existing SR-IOV/DPDK functionality
- Update status reporting to include IPv6 information

### 4. Controller Logic Enhancement
- Extend NodeENI controller to handle IPv6 subnets
- Add validation for IPv6 subnet configurations
- Implement IPv6-aware reconciliation logic
- Support for mixed IPv4/IPv6 environments

## Acceptance Criteria

### Core IPv6 Functionality
- [ ] NodeENI CRD supports IPv6 subnet configuration fields
- [ ] Controller can create and attach ENIs to IPv6 subnets
- [ ] Support for IPv6-only ENI configurations
- [ ] Support for dual-stack (IPv4 + IPv6) ENI configurations
- [ ] Proper IPv6 address assignment and management
- [ ] IPv6 subnet validation and error handling

### Status and Monitoring
- [ ] ENI attachment status includes IPv6 addresses and subnet information
- [ ] IPv6 subnet CIDR information displayed in status
- [ ] Proper error reporting for IPv6-related issues
- [ ] Comprehensive logging for IPv6 operations

### Integration Compatibility
- [ ] IPv6 support works with existing SR-IOV configurations
- [ ] IPv6 support works with existing DPDK configurations
- [ ] Compatible with Multus CNI for IPv6 secondary networks
- [ ] No breaking changes to existing IPv4-only configurations

### AWS Integration
- [ ] Full integration with AWS VPC IPv6 functionality
- [ ] Support for IPv6 security group rules
- [ ] Proper handling of IPv6 routing and gateways
- [ ] Integration with AWS IPv6 prefix delegation (future)

### Testing
- [ ] Unit tests for IPv6 configuration logic
- [ ] Integration tests for IPv6-only scenarios
- [ ] Integration tests for dual-stack scenarios
- [ ] End-to-end tests with Multus CNI and IPv6
- [ ] Performance tests for IPv6 vs IPv4 performance

## Technical Considerations

### 1. AWS VPC IPv6 Requirements
- VPC must have IPv6 CIDR block assigned
- Subnets must have IPv6 CIDR blocks configured
- Route tables must include IPv6 routes
- Security groups must allow IPv6 traffic

### 2. Kubernetes IPv6 Support
- Ensure cluster supports IPv6 (dual-stack or IPv6-only)
- Pod networking must be IPv6-capable
- Service discovery and DNS must support IPv6
- Ingress controllers must support IPv6

### 3. Container Runtime Considerations
- Container runtime must support IPv6 networking
- CNI plugins must be IPv6-capable
- Network policies must support IPv6 rules

### 4. Backwards Compatibility
- Existing IPv4-only NodeENI resources must continue to work
- No changes to existing API behavior
- Graceful handling of mixed IPv4/IPv6 environments
- Optional IPv6 configuration (disabled by default)

## Migration Strategy

### Phase 1: Basic IPv6 Support
- Add IPv6 subnet configuration to NodeENI CRD
- Implement IPv6 ENI creation and attachment
- Basic IPv6 status reporting

### Phase 2: Dual-Stack Support
- Support for both IPv4 and IPv6 in single NodeENI
- Enhanced status reporting for dual-stack
- Comprehensive testing

### Phase 3: Advanced Features
- IPv6 prefix delegation support
- Advanced IPv6 routing configurations
- Performance optimizations

## Related Work

- **Current ENI Management**: Build upon existing ENI attachment logic in v1.3.5
- **SR-IOV Integration**: Ensure IPv6 works with current SR-IOV functionality
- **DPDK Integration**: Maintain IPv6 compatibility with DPDK configurations
- **Multus CNI**: Leverage existing Multus integration for IPv6 secondary networks

## Future Enhancements

- **IPv6 Prefix Delegation**: Support for AWS IPv6 prefix delegation
- **IPv6 Load Balancing**: Integration with AWS IPv6 load balancers
- **IPv6 Monitoring**: Enhanced metrics and monitoring for IPv6 networks
- **IPv6 Security**: Advanced IPv6 security group and NACLs support
- **IPv6 Performance**: IPv6-specific performance optimizations

---

**Baseline Version**: v1.3.5  
**Priority**: High (IPv6 adoption is accelerating)  
**Complexity**: High  
**Dependencies**: AWS VPC IPv6 support, Kubernetes IPv6 support

Feature Request: Add IPv6 subnet support for ENI attachments #25

Description

Summary

Motivation

Feature Description

Core Functionality

Proposed NodeENI Resource Schema

Example Configurations

1. IPv6-Only ENI

2. Dual-Stack ENI (IPv4 + IPv6)

3. IPv6 with SR-IOV (Non-DPDK)

4. IPv6 with DPDK

5. Multus CNI NetworkAttachmentDefinition for IPv6

Implementation Approach

1. NodeENI CRD Updates

2. AWS EC2 Client Enhancement

3. ENI Manager Updates

4. Controller Logic Enhancement

Acceptance Criteria

Core IPv6 Functionality

Status and Monitoring

Integration Compatibility

AWS Integration

Testing

Technical Considerations

1. AWS VPC IPv6 Requirements

2. Kubernetes IPv6 Support

3. Container Runtime Considerations

4. Backwards Compatibility

Migration Strategy

Phase 1: Basic IPv6 Support

Phase 2: Dual-Stack Support

Phase 3: Advanced Features

Related Work

Future Enhancements

Metadata

Metadata

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Labels

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Milestone

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