Changing BMC Address

There are situations where you may need to change the BMC (Baseboard Management Controller) address of a BareMetalHost:

• The BMC hardware has failed and been replaced
• The BMC network configuration has changed (e.g., IP address reassignment)
• A mistake was made when initially setting the BMC address
• Network infrastructure changes require BMC address updates

This document explains how to update the BMC address of an existing BareMetalHost.

When Can the BMC Address Be Changed?

The BMC address can be updated in the following scenarios:

1. When the host is in the registering state - This is the initial state when a BareMetalHost is first created and Ironic is attempting to register it.

2. When the host is detached - By using the detached annotation, you can temporarily remove the host from Ironic’s management, update the BMC address, and then reattach it.

The BMC address cannot be changed while the host is actively managed by Ironic in other states without first detaching it.

Procedure for changing the BMC address

1. Check the current status of your BareMetalHost(s):

   $ kubectl get baremetalhost -o wide
   NAME   STATUS     STATE         CONSUMER           BMC                                 ONLINE   ERROR     AGE
   bmh1   detached   provisioned   metal3-k8s-426jf   redfish-virtualmedia://192.168.1.32    true               108d
   bmh2   OK         registering                      redfish-virtualmedia://192.168.1.33    true               3s
   

2. If the state is registering or the status is detached, you can directly edit the BMC address.

3. If this is not the case, you need to detach the host first. NOTE: Make sure it is in a stable provisioning state, e.g. Provisioned or Available before this!

   kubectl annotate baremetalhost -n <namespace> <host-name> \
   baremetalhost.metal3.io/detached="updating-bmc"
   

4. Wait for the host to become detached:

   kubectl -n <namespace> wait baremetalhost <host-name> --for=jsonpath='{.status.operationalStatus}'=detached
   

5. Edit the BareMetalHost resource:

   kubectl edit baremetalhost -n <namespace> <host-name>
   

6. Update the spec.bmc.address field to the new BMC address:

   spec:
     bmc:
       address: redfish://192.168.1.100  # Update to new address
       credentialsName: host-bmc-secret
   

7. If needed, also update the BMC credentials secret.

8. Remove the detached annotation to reattach the host:

   kubectl annotate baremetalhost -n <namespace> <host-name> \
     baremetalhost.metal3.io/detached-
   

   Note the trailing - which removes the annotation.

9. Wait for the host to be reattached:

   kubectl -n <namespace> wait baremetalhost <host-name> --for=jsonpath='{.status.operationalStatus}'=OK
   

Important Considerations

• Ensure stable state: Do not try to change the BMC address in the middle of other operations, or if external processes or tools are interacting with the host. Make sure it is in a stable provisioning state, e.g. Provisioned or Available before considering a change.

• Host state is preserved: When you detach and reattach a host, the provisioning state is preserved. A Provisioned host will remain Provisioned, and an Available host will remain Available.

• No deprovisioning occurs: Using the detached annotation ensures that the host is not deprovisioned when you update the BMC address.

• BMC credentials: If the BMC replacement also changed the username or password, make sure to update the credentials secret before removing the detached annotation.

• MAC address remains the same: The bootMACAddress should remain unchanged even when the BMC is replaced, as it refers to the server’s network interface, not the BMC.

Related Documentation

• Detaching Hosts from Provisioner - Detailed information about the detached annotation

References

• PR #1549: Allow BMC address to be updated