Overview MetalLB is a load balancer implementation for bare metal Kubernetes clusters. It provides LoadBalancer-type service support, which is typically only available in cloud environments.
HelmRelease Configuration MetalLB is deployed using Flux with the following HelmRelease:
apiVersion : helm.toolkit.fluxcd.io/v2 kind : HelmRelease metadata : name : metallb spec : chart : spec : chart : metallb sourceRef : kind : HelmRepository name : metallb version : "=0.15.3" interval : 24h releaseName : metallb install : crds : Create upgrade : crds : CreateReplace
Key Configuration MetalLB Helm chart version. Currently using 0.15.3
How often Flux checks for chart updates
CRD management strategy during installation
IP Address Pool Configuration MetalLB requires an IPAddressPool resource to define the range of IP addresses it can assign:
apiVersion : metallb.io/v1beta1 kind : IPAddressPool metadata : name : first-pool namespace : metallb-system spec : addresses : - 192.168.10.0/24
L2 Advertisement For Layer 2 mode, configure L2Advertisement to announce IP addresses:
apiVersion : metallb.io/v1beta1 kind : L2Advertisement metadata : name : l2-advertisement namespace : metallb-system spec : ipAddressPools : - first-pool
L2 mode is simpler to configure but requires that MetalLB nodes are on the same Layer 2 network as your clients.
Operating Modes Layer 2 mode uses ARP (for IPv4) or NDP (for IPv6) to announce service IPs: Advantages:
Simple configuration
No special network equipment required
Works with standard switches
Limitations:
All traffic goes through a single node
Failover can take a few seconds
Configuration: apiVersion : metallb.io/v1beta1 kind : L2Advertisement metadata : name : l2-advertisement spec : ipAddressPools : - first-pool
BGP mode peers with your network routers using the BGP protocol: Advantages:
True load balancing across multiple nodes
Faster failover
Better scalability
Requirements:
BGP-capable router
Network configuration for BGP peering
Configuration: apiVersion : metallb.io/v1beta1 kind : BGPAdvertisement metadata : name : bgp-advertisement spec : ipAddressPools : - first-pool peers : - 192.168.1.1
Using LoadBalancer Services
Create a LoadBalancer service
Define a service with type LoadBalancer: apiVersion : v1 kind : Service metadata : name : my-app namespace : default spec : type : LoadBalancer selector : app : my-app ports : - port : 80 targetPort : 8080 protocol : TCP
Apply the service
kubectl apply -f service.yaml
Verify IP assignment
Check that MetalLB assigned an external IP: Expected output: NAME TYPE CLUSTER-IP EXTERNAL-IP PORT(S) my-app LoadBalancer 10.96.100.50 192.168.10.10 80:30123/TCP
Test connectivity
Access the service using the external IP: curl http://192.168.10.10
Advanced Configuration Requesting Specific IP Addresses You can request a specific IP from the pool:
apiVersion : v1 kind : Service metadata : name : my-app spec : type : LoadBalancer loadBalancerIP : 192.168.10.50 # Request specific IP selector : app : my-app ports : - port : 80 targetPort : 8080
IP Sharing Multiple services can share the same IP using the metallb.universe.tf/allow-shared-ip annotation:
http-service.yaml
https-service.yaml
apiVersion : v1 kind : Service metadata : name : http-service annotations : metallb.universe.tf/allow-shared-ip : "shared-ip-key" spec : type : LoadBalancer loadBalancerIP : 192.168.10.100 ports : - port : 80 protocol : TCP
When sharing IPs, ensure services use different ports to avoid conflicts.
kubectl get pods -n metallb-system
Expected output:
NAME READY STATUS RESTARTS AGE controller-xxxxxxxxxx-xxxxx 1/1 Running 0 5d speaker-xxxxx 1/1 Running 0 5d speaker-yyyyy 1/1 Running 0 5d
View IP address pools kubectl get ipaddresspools -n metallb-system
Check allocated IPs kubectl get svc --all-namespaces -o wide | grep LoadBalancer
Troubleshooting Service stuck in pending If a LoadBalancer service remains in pending:
Check if IPAddressPool is configured:
kubectl get ipaddresspools -n metallb-system
Verify pool has available IPs:
kubectl describe ipaddresspool first-pool -n metallb-system
Check MetalLB controller logs:
kubectl logs -n metallb-system -l app.kubernetes.io/component=controller
IP not reachable
Verify L2Advertisement is configured:
kubectl get l2advertisements -n metallb-system
Check speaker logs:
kubectl logs -n metallb-system -l app.kubernetes.io/component=speaker
Verify network connectivity from speaker nodes
Best Practices
Define IP pools carefully to avoid conflicts with your network DHCP range
Use L2 mode for simplicity in small to medium deployments
Consider BGP mode for production environments requiring high availability
Monitor IP address pool utilization to prevent exhaustion
Document IP assignments for services in your infrastructure documentation
Resources