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MetalLB

As explained in Acing the Certified Kubernetes Administrator Exam, Second Edition

MetalLB is a Kubernetes load-balancer implementation that provides external load-balancing capabilities for clusters without an integrated cloud load balancer.

MetalLB provides load-balancing for Kubernetes clusters such as kind, allowing a LoadBalancer Service to receive an externally reachable IP without an integrated cloud load balancer. section 5.3.1 section 6.4.3

Deploy and configure MetalLB as an operational workflow:

  • Install the chart with helm install metallb metallb/metallb --values values.yaml; the values file configures chart parameters in YAML. section 5.3.1
  • Configure an IPAddressPool and L2Advertisement, using an address range that matches the node network’s address prefix. section 6.4.3
  • Expose an application by changing its Service type to LoadBalancer, then inspect EXTERNAL-IP with kubectl get svc. section 6.4.3

Expose Apache through MetalLB

After configuring the pool 172.18.255.1-172.18.255.50 and applying the layer-2 resources, apache-svc reports type LoadBalancer and EXTERNAL-IP 172.18.255.1. Running curl 172.18.255.1 returns the Apache response.

How Acing the Certified Kubernetes Administrator Exam, Second Edition covers it

How deep it goes
Explains Helm installation, node-network-based address configuration, layer-2 resources, service exposure, and curl verification.
Examples
Uses a kind cluster, an Apache Service, a 172.18.255.1–172.18.255.50 pool, kubectl output, and curl verification.
What it assumes
Assumes a running kind cluster and basic Helm and kubectl usage, while demonstrating node-IP discovery and Service exposure.
What you can do after
Operate MetalLB by installing its Helm chart or manifests, assigning an address pool, exposing a Service, and verifying external access.
How it connects
Connects Kubernetes Services with Helm, LoadBalancer, NodePort, ClusterIP, IPAddressPool, and L2Advertisement resources.
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Related concepts

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