Configuring MetalLB address pools - Load balancing with MetalLB | Networking

About the IPAddressPool custom resource
Configuring an address pool
Example address pool configurations
Additional resources
Next steps

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 address pool custom resource definition (CRD) and API documented in "Load balancing with MetalLB" in OKD 4.10 can still be used in 4.11. However, the enhanced functionality associated with advertising the IPAddressPools with layer 2 or the BGP protocol is not supported when using the address pool CRD.

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

Table 1. MetalLB IPAddressPool pool custom resource
Field	Type	Description
`metadata.name`	`string`	Specifies the name for the address pool. When you add a service, you can specify this pool name in the `metallb.universe.tf/address-pool` annotation to select an IP address from a specific pool. The names `doc-example`, `silver`, and `gold` are used throughout the documentation.
`metadata.namespace`	`string`	Specifies the namespace for the address pool. Specify the same namespace that the MetalLB Operator uses.
`metadata.label`	`string`	Optional: Specifies the key value pair assigned to the `IPAddressPool`. This can be referenced by the `ipAddressPoolSelectors` in the `BGPAdvertisement` and `L2Advertisement` CRD to associate the `IPAddressPool` with the advertisement
`spec.addresses`	`string`	Specifies a list of IP addresses for MetalLB Operator to assign to services. You can specify multiple ranges in a single pool; they will all share the same settings. Specify each range in CIDR notation or as starting and ending IP addresses separated with a hyphen.
`spec.autoAssign`	`boolean`	Optional: Specifies whether MetalLB automatically assigns IP addresses from this pool. Specify `false` if you want explicitly request an IP address from this pool with the `metallb.universe.tf/address-pool` annotation. The default value is `true`.

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

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.

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

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.