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Alex Spinov
Alex Spinov

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MetalLB Has a Free API — Load Balancing for Bare Metal Kubernetes

#kubernetes #cloudnative #networking #devops

MetalLB: Load Balancers Without Cloud Providers

Running Kubernetes on bare metal? No AWS ELB, no GCP Load Balancer. Your LoadBalancer services stay in "Pending" forever. MetalLB fixes this by providing network load balancers for bare metal clusters.

How MetalLB Works

MetalLB operates in two modes:

  • Layer 2 (ARP/NDP) — simple, works everywhere, single-node bottleneck
  • BGP — production-grade, true load balancing across nodes

The Free API (CRDs)

MetalLB is configured entirely through Kubernetes CRDs:

apiVersion: metallb.io/v1beta1
kind: IPAddressPool
metadata:
  name: production-pool
  namespace: metallb-system
spec:
  addresses:
  - 192.168.1.240-192.168.1.250
---
apiVersion: metallb.io/v1beta1
kind: L2Advertisement
metadata:
  name: l2-advert
  namespace: metallb-system
spec:
  ipAddressPools:
  - production-pool
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# Check allocated IPs
kubectl get ipaddresspools -n metallb-system

# See which services got IPs
kubectl get svc -A | grep LoadBalancer

# BGP session status
kubectl get bgppeers -n metallb-system
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Real-World Use Case

A fintech company running on-prem Kubernetes for compliance reasons couldn't use cloud load balancers. MetalLB with BGP mode gave them production-grade load balancing with failover — no cloud dependency, full data sovereignty.

Quick Start 

kubectl apply -f https://raw.githubusercontent.com/metallb/metallb/v0.14.5/config/manifests/metallb-native.yaml

# Wait for pods
kubectl wait --namespace metallb-system --for=condition=ready pod --selector=app=metallb -l 120s
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Layer 2 vs BGP

Feature Layer 2 BGP
Setup Simple Requires router config
Failover ~10s Sub-second
Load distribution Single node All nodes
Best for Dev/small clusters Production

Key Features

  • No cloud vendor lock-in — works on any bare metal or VM cluster
  • Dual-stack — IPv4 and IPv6 support
  • Multiple pools — different IP ranges for different namespaces
  • FRR mode — modern BGP implementation with advanced features

Resources

Need automated data collection for your infrastructure? Check out my web scraping tools on Apify or email spinov001@gmail.com for custom solutions.

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