Add Kubernetes Integration Guide for Milvus Semantic Cache

[Xunzhuo]

Is your feature request related to a problem? Please describe.

Currently, the semantic router supports Milvus as a semantic cache backend and has comprehensive Kubernetes deployment manifests. However, there's no integrated guide for deploying Milvus alongside the semantic router in Kubernetes environments. Users need to:

1. Manually deploy Milvus in Kubernetes
2. Configure network connectivity between semantic router and Milvus
3. Handle authentication, persistence, and scaling considerations
4. Manage configuration updates for production deployments

This creates a barrier for users wanting to leverage the full power of persistent, distributed semantic caching in Kubernetes environments, especially for production deployments requiring high availability and scalability.

Describe the solution you'd like

Create a comprehensive Kubernetes integration guide for Milvus that includes:

1. Milvus Deployment Options

• Helm chart deployment for Milvus standalone and cluster modes
• Kubernetes manifests for Milvus with proper resource allocation
• Integration with existing semantic router namespace and networking

2. Configuration Management

• Kubernetes ConfigMap/Secret management for Milvus connection details
• Environment-specific configurations (development, staging, production)
• TLS and authentication setup for secure connections

3. Networking and Service Discovery

• Service definitions for Milvus within the cluster
• Network policies for secure communication
• DNS-based service discovery configuration

4. Persistence and Storage

• PersistentVolume configurations for Milvus data
• Storage class recommendations for different cloud providers
• Backup and recovery strategies

5. Monitoring and Observability

• Prometheus metrics integration for Milvus
• Grafana dashboards for cache performance monitoring
• Health checks and readiness probes

6. Production Considerations

• Resource requirements and scaling guidelines
• High availability setup with Milvus cluster mode
• Performance tuning for different workload patterns

7. Example Deployments

• Complete working examples for different scenarios:
  • Development setup with Milvus standalone
  • Production setup with Milvus cluster
  • Cloud-specific deployments (EKS, GKE, AKS)

8. Migration Guide

• Steps to migrate from memory cache to Milvus
• Data migration strategies
• Rollback procedures

Additional context

Current State:

• Milvus cache backend is implemented (src/semantic-router/pkg/cache/milvus_cache.go)
• Kubernetes deployment manifests exist (deploy/kubernetes/)
• Milvus configuration template available (config/cache/milvus.yaml)
• Current K8s config uses memory backend (deploy/kubernetes/config.yaml)

Technical Requirements:

• Support for Milvus v2.3.3+ (current version used in tools/make/milvus.mk)
• Integration with existing semantic router architecture
• Compatibility with Gateway API and Envoy AI Gateway
• Support for both development and production environments

Documentation Structure:

• Add to existing Kubernetes documentation (website/docs/installation/kubernetes.md)
• Create dedicated Milvus integration section
• Include practical examples and troubleshooting guides
• Provide performance benchmarking guidelines

Related Files:

• deploy/kubernetes/config.yaml - Update to include Milvus option
• config/cache/milvus.yaml - Reference configuration
• website/docs/tutorials/semantic-cache/milvus-cache.md - Existing Milvus docs
• deploy/kubernetes/README.md - Integration point for new guide

This enhancement will significantly improve the user experience for production deployments and enable users to fully leverage the semantic router's caching capabilities at scale.

[Xunzhuo]

/area core networking docs
/milestone v0.1
/priority P1

[samzong]

/assign @samzong