Configuring MetalLB address pools

As a cluster administrator, you can add, modify, and delete address pools. The MetalLB Operator uses the address pool custom resources to set the IP addresses that MetalLB can assign to services. The namespace used in the examples assume the namespace is metallb-system.

About the IPAddressPool custom resource

The fields for the IPAddressPool custom resource are described in the following tables.

You can assign IP addresses from an IPAddressPool to services and namespaces by configuring the spec.serviceAllocation specification.

Configuring an address pool

As a cluster administrator, you can add address pools to your cluster to control the IP addresses that MetalLB can assign to load-balancer services.

Prerequisites

• Install the OpenShift CLI (oc).

• Log in as a user with cluster-admin privileges.

Procedure

1. Create a file, such as ipaddresspool.yaml, with content like the following example:

   apiVersion: metallb.io/v1beta1
   kind: IPAddressPool
   metadata:
     namespace: metallb-system
     name: doc-example
     labels: (1)
       zone: east
   spec:
     addresses:
     - 203.0.113.1-203.0.113.10
     - 203.0.113.65-203.0.113.75

   1	This label assigned to the IPAddressPool can be referenced by the ipAddressPoolSelectors in the BGPAdvertisement CRD to associate the IPAddressPool with the advertisement.

2. Apply the configuration for the IP address pool:

   $ oc apply -f ipaddresspool.yaml

Verification

• View the address pool:

  $ oc describe -n metallb-system IPAddressPool doc-example

  Example output

  Name:         doc-example
  Namespace:    metallb-system
  Labels:       zone=east
  Annotations:  <none>
  API Version:  metallb.io/v1beta1
  Kind:         IPAddressPool
  Metadata:
    ...
  Spec:
    Addresses:
      203.0.113.1-203.0.113.10
      203.0.113.65-203.0.113.75
    Auto Assign:  true
  Events:         <none>

Confirm that the address pool name, such as doc-example, and the IP address ranges appear in the output.

Example address pool configurations

Example: IPv4 and CIDR ranges

You can specify a range of IP addresses in CIDR notation. You can combine CIDR notation with the notation that uses a hyphen to separate lower and upper bounds.

apiVersion: metallb.io/v1beta1
kind: IPAddressPool
metadata:
  name: doc-example-cidr
  namespace: metallb-system
spec:
  addresses:
  - 192.168.100.0/24
  - 192.168.200.0/24
  - 192.168.255.1-192.168.255.5

Example: Reserve IP addresses

You can set the autoAssign field to false to prevent MetalLB from automatically assigning the IP addresses from the pool. When you add a service, you can request a specific IP address from the pool or you can specify the pool name in an annotation to request any IP address from the pool.

apiVersion: metallb.io/v1beta1
kind: IPAddressPool
metadata:
  name: doc-example-reserved
  namespace: metallb-system
spec:
  addresses:
  - 10.0.100.0/28
  autoAssign: false

Example: IPv4 and IPv6 addresses

You can add address pools that use IPv4 and IPv6. You can specify multiple ranges in the addresses list, just like several IPv4 examples.

Whether the service is assigned a single IPv4 address, a single IPv6 address, or both is determined by how you add the service. The spec.ipFamilies and spec.ipFamilyPolicy fields control how IP addresses are assigned to the service.

apiVersion: metallb.io/v1beta1
kind: IPAddressPool
metadata:
  name: doc-example-combined
  namespace: metallb-system
spec:
  addresses:
  - 10.0.100.0/28
  - 2002:2:2::1-2002:2:2::100

Example: Assign IP address pools to services or namespaces

You can assign IP addresses from an IPAddressPool to services and namespaces that you specify.

If you assign a service or namespace to more than one IP address pool, MetalLB uses an available IP address from the higher-priority IP address pool. If no IP addresses are available from the assigned IP address pools with a high priority, MetalLB uses available IP addresses from an IP address pool with lower priority or no priority.

apiVersion: metallb.io/v1beta1
kind: IPAddressPool
metadata:
  name: doc-example-service-allocation
  namespace: metallb-system
spec:
  addresses:
    - 192.168.20.0/24
  serviceAllocation:
    priority: 50 (1)
    namespaces: (2)
      - namespace-a
      - namespace-b
    namespaceSelectors: (3)
      - matchLabels:
          zone: east
    serviceSelectors: (4)
      - matchExpressions:
        - key: security
          operator: In
          values:
          - S1

Additional resources

• Configuring MetalLB with an L2 advertisement and label.

Next steps

• For BGP mode, see Configuring MetalLB BGP peers.

• Configuring services to use MetalLB.