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MetalLB Load Balancer

This directory contains the MetalLB configuration for providing LoadBalancer services in the bare-metal Kubernetes environment.

Components

Features

Load Balancer Services

MetalLB enables LoadBalancer service types in bare-metal environments by:

  • IP Address Assignment: Automatic external IP allocation from configured pools
  • Traffic Distribution: Layer 2 or BGP-based load balancing
  • Service Integration: Seamless integration with Kubernetes Service resources
  • High Availability: Automatic failover for service endpoints

Address Pool Management

Configured IP address pools for different service types:

  • Public Services: Externally accessible services
  • Private Services: Internal network access only
  • Reserved Ranges: Dedicated IP ranges for specific applications
  • Dynamic Allocation: Automatic IP assignment from available pools

Configuration Modes

Layer 2 Mode

Default configuration using Layer 2 for:

  • Simple Setup: No router configuration required
  • ARP/NDP: Address resolution at Layer 2
  • Single Node: One node announces IP at a time
  • Fast Failover: Quick recovery during node failures

BGP Mode (Optional)

Advanced BGP configuration for:

  • Multi-path Routing: ECMP load distribution
  • Router Integration: Direct integration with network infrastructure
  • Scalable Design: Better performance for high-traffic services
  • Graceful Shutdown: Controlled traffic drain during maintenance

Service Types

Ingress Controllers

MetalLB provides external IPs for:

  • Nginx Ingress: HTTP/HTTPS traffic handling
  • Envoy Gateway: Modern API gateway services
  • Custom Ingress: Application-specific ingress controllers

Application Services

Direct external access for:

  • Database Services: External database connectivity
  • Monitoring Tools: Observability platform access
  • Development Services: Remote development environments
  • Gaming Services: Game server external access

Network Integration

Cilium Integration

MetalLB works with Cilium CNI for:

  • Traffic Routing: Efficient packet forwarding
  • Network Policies: Security policy enforcement
  • Load Balancing: Distributed load balancing
  • Observability: Network flow monitoring

External Access

Services are accessible through:

  • Direct IP Access: External IP assignment
  • DNS Integration: Automatic DNS record creation
  • Port Management: Flexible port allocation
  • Protocol Support: TCP, UDP, and SCTP protocols

Address Pool Configuration

Pool Allocation

IP addresses are allocated from pools based on:

  • Service Annotations: Explicit pool selection
  • Namespace Labels: Automatic pool assignment
  • Service Type: Default pools for different service categories
  • Resource Constraints: Available IP address limits

IP Range Management

  • CIDR Notation: Flexible IP range specification
  • Auto-assignment: Dynamic IP allocation
  • Reserved Addresses: Static IP assignment for critical services
  • Pool Sharing: Multiple services sharing pool resources

Monitoring and Observability

Metrics Collection

MetalLB exposes metrics for:

  • IP Pool Usage: Available vs. allocated addresses
  • Service Status: LoadBalancer service health
  • BGP Sessions: BGP peer connectivity (if enabled)
  • Traffic Statistics: Load balancer traffic patterns

Health Monitoring

  • Controller Health: MetalLB controller pod status
  • Speaker Health: Node-level speaker pod monitoring
  • Service Reachability: External connectivity testing
  • Failover Events: Load balancer failover tracking

Troubleshooting

Common Issues

  • IP Exhaustion: Pool capacity and allocation monitoring
  • ARP Conflicts: Layer 2 address resolution problems
  • BGP Connectivity: Routing protocol troubleshooting
  • Service Annotation: Proper service configuration

Debugging Commands

# Check MetalLB controller status
kubectl get pods -n metallb-system

# View IP pool configuration  
kubectl get ipaddresspools -n metallb-system

# Check service external IP assignment
kubectl get svc -A -o wide

# View MetalLB logs
kubectl logs -n metallb-system -l app=metallb

Security Considerations

Network Policies

MetalLB traffic is controlled through:

  • Speaker Policies: Control plane communication rules
  • BGP Policies: Routing protocol security (if enabled)
  • Service Policies: Application-specific network rules
  • Ingress Filtering: Traffic source validation

Access Control

  • RBAC Configuration: Controller service account permissions
  • Network Segmentation: Isolated MetalLB traffic flows
  • Audit Logging: Load balancer configuration changes
  • Certificate Management: BGP authentication (if enabled)