This guide explains how to reinstall a compute node from Centos8 Stream-Yoga to AlmaLinux9-Yoga
In the following instructions the node cld-np-19, an INFN node, is the one to be reinstallated
First of all disable the compute node, so that no new VMs will be instantiated on this compute node:
openstack compute service set --disable cld-np-19.cloud.pd.infn.it nova-compute
To check if the compute node was actually disabled:
openstack compute service list
Then finds all the virtual machines instantiated on this compute node:
openstack server list --all --host cld-np-19.cloud.pd.infn.it
Then migrate each VM instantiated on this compute node to other hypervisors.
To avoid the migration of the same virtual machine multiple times, please migrate the VM on a compute node that was already migrated to AlmaLinux9
The migration of a virtual machine usually requires a downtime (~ 15') of that VM, unless the VM was created using a volume. So before migrating the VM you must agree this operation with the relevant owner.
E.g. to find the owner of a VM with UUID be832766-7996-4ccf-a9c1-5eec2e5f8fd3:
[root@cld-ctrl-01 ~]# openstack server show be832766-7996-4ccf-a9c1-5eec2e5f8fd3 | grep user_id
| user_id | 7681252c430040e7bb96c7c4f7c88464 |
[root@cld-ctrl-01 ~]# openstack user show 7681252c430040e7bb96c7c4f7c88464
+---------------------+----------------------------------+
| Field | Value |
+---------------------+----------------------------------+
| domain_id | default |
| email | Ysabella.Ong@lnl.infn.it |
| enabled | True |
| id | 7681252c430040e7bb96c7c4f7c88464 |
| name | ysaong@infn.it |
| options | {} |
| password_expires_at | None |
+---------------------+----------------------------------+
To migrate a virtual machine to another compute node, there are two possible procedures:
- Procedure to be used if the VM was created using a volume (the migration procedure doesn't require a downtime)
- Procedure to be used if the VM was created using ephemeral storage (the migration procedure requires a downtime)
- Install the operating system using foreman. For this use the hosts_all foreman hostgroup
- Disable SELinux
- Configure the management and data network
- Stop puppet:
systemctl stop puppet
- In foreman move the host under the ComputeNode-Prod_Yoga hostgroup
Run puppet manually:
If the configuration fails reportingpuppet agent -t
error: "net.bridge.bridge-nf-call-ip6tables" is an unknown key error: "net.bridge.bridge-nf-call-iptables" is an unknown key error: "net.bridge.bridge-nf-call-arptables" is an unknown key
then please issue:
modprobe br_netfilter
and then rerun puppet
In the configuration fails reporting a problem because of a wrong dependency required by swtpm, then issue:
mv /etc/yum.repos.d/advanced-virtualization.repo /etc/yum.repos.d/advanced-virtualization.repo.old yum install centos-release-advanced-virtualization
and then rerun puppet
Disable the compute node so that it doesn't accept new VMs:
openstack compute service set --disable cld-np-19.cloud.pd.infn.it nova-compute
Start and enablepuppet:
systemctl start puppet; systemctl enable puppet
Enable the checks in Nagios for this host
Wait till all checks are ok (in particular the VM network and volume one: remember to enable the node just for the time to force the run from Nagios; othwerwise the check will fail.)
- Add this node in the following scripts on cld-ctrl-01: /usr/local/bin/display_usage_of_hypervisors.sh, /usr/local/bin/host_aggregate.sh, /usr/local/bin/new_project.sh, /usr/local/bin/free_resources_compute_nodes.sh
- Add this node in the /etc/cron.daily/vm-log.sh script on cld-log
- Create the directory /var/disk-iscsi/qemu/cld-np-19 in cld-log
- Verify that a ssh from root@cld-log to root@cld-np-19 works without requiring password
Stop puppet on the 2 controller nodes:
systemctl stop puppet
Add the new compute node in cld-config:/var/puppet/puppet_yoga/controller_yoga/templates/aai_settings.py.erb
Run puppet on the first controller node (this will trigger a restart of httpd):
puppet agent -t
Run puppet on the second controller node (this will trigger a restart of httpd):
puppet agent -t
Start puppet on the two controller nodes:
systemctl start puppet
Enable the host:
openstack compute service set --enable cld-np-19.cloud.pd.infn.it nova-compute
- Add the host to the 'admin' aggregate
Run the aggregate_manage.sh script to add the node in the relevant hostgroups, e.g.:
/usr/local/bin/aggregate_manage.sh add cld-np-19.cloud.pd.infn.it INFN