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Set a custom external IP address for the DHCP service

Available since MCC 2.25.0 (Cluster release 16.0.0)

This section instructs you on how to set a custom external IP address for the dhcp-lb service so that it remains the same during management cluster upgrades and other LCM operations.

The changes of dhcp-lb service address may lead to the necessity of changing configuration for DHCP relays on ToR switches. The described procedure allows you to avoid such unwanted changes. This configuration makes sense when you use multiple DHCP address ranges on your deployment. See Configure multiple DHCP address ranges for details.

To set a custom external IP address for the dhcp-lb service:

1. In the Cluster object of the management cluster, modify the configuration of the baremetal-operator release by setting dnsmasq.dedicated_udp_service_address_pool to true:

   spec:
     ...
     providerSpec:
       value:
         kaas:
           ...
           regional:
             - helmReleases:
               ...
               - name: baremetal-operator
                 values:
                   dnsmasq:
                     dedicated_udp_service_address_pool: true
                     ...
               provider: baremetal
             ...
   

2. In the MetalLBConfig object of the management cluster, modify the ipAddressPools object list by adding the dhcp-lb object and the serviceAllocation parameters for the default object:

   ipAddressPools:
   - name: default
     spec:
       addresses:
       - 112.181.11.41-112.181.11.60
       autoAssign: true
       avoidBuggyIPs: false
       serviceAllocation:
         serviceSelectors:
         - matchExpressions:
           - key: app.kubernetes.io/name
             operator: NotIn
             values:
             - dhcp-lb
   - name: services-pxe
     spec:
       addresses:
       - 10.0.24.122-10.0.24.140
       autoAssign: false
       avoidBuggyIPs: false
   - name: dhcp-lb
     spec:
       addresses:
       - 10.0.24.121/32
       autoAssign: true
       avoidBuggyIPs: false
       serviceAllocation:
         namespaces:
         - kaas
         serviceSelectors:
         - matchExpressions:
           - key: app.kubernetes.io/name
             operator: In
             values:
             - dhcp-lb
   

   Select non-overlapping IP addresses for all the ipAddressPools that you use: default, services-pxe, and dhcp-lb.

3. In the MetalLBConfig object of the management cluster, modify the l2Advertisements object list by adding dhcp-lb to the ipAddressPools section in the pxe object spec:

   Note

   A cluster may have a different L2Advertisement object name instead of pxe.

   l2Advertisements:
   ...
   - name: pxe
     spec:
       ipAddressPools:
       - services-pxe
       - dhcp-lb
       ...