$ oadm manage-node <node_name> --schedulable=false
Updating or upgrading your operating system (OS), by either changing OS versions
or updating the system software, can impact the OpenShift Origin software running
on those machines. In particular, these updates can affect the iptables rules
or ovs flows that OpenShift Origin requires to operate.
Use the following to safely upgrade the OS on a host:
Ensure the host is unschedulable, meaning that no new pods will be placed onto the host:
$ oadm manage-node <node_name> --schedulable=false
Migrate the pods from the host:
$ oadm drain <node_name> --force --delete-local-data --ignore-daemonsets
Install or update the *-excluder packages on each host with the following. This ensures the hosts stay on the correct versions of OpenShift Origin, as per the atomic-openshift and docker packages, instead of the most current versions:
# yum install atomic-openshift-excluder atomic-openshift-docker-excluder
This adds entries to the exclude directive in the host’s /etc/yum.conf
file.
Update or upgrade the host packages, and reboot the host. A reboot ensures
that the host is running the newest versions, and means that the docker and
OpenShift Origin processes have been restarted, which will force them to check
that all of the rules in other services are correct.
However, instead of rebooting a node host, you can restart the services that are
affected, or preserve the iptables state. Both processes are described in the
OpenShift Origin
IPtables topic. The ovs flow rules do not need to be saved, but restarting
the OpenShift Origin node software will fix the flow rules.
Configure the host to be schedulable again:
$ oadm manage-node <node_name> --schedulable=true