When you need to repair or maintain nodes, you should first put the nodes into maintenance mode. Putting nodes into maintenance mode safely drains their pods/workloads and excludes the nodes from pod scheduling. In maintenance mode, you can work on your nodes without a risk of disrupting pod traffic.
Choose the nodes you want to put into maintenance mode by specifying IP ranges
for the selected nodes under maintenanceBlocks
in your cluster configuration
file. The nodes you choose must be in a ready state, and functioning in the
cluster.
Steps to put nodes into maintenance mode
To put nodes into maintenance mode:
Edit the cluster configuration file to select the nodes you want to put into maintenance mode.
You can edit the configuration file with an editor of your choice, or you can edit the cluster custom resource directly by running the following command:
kubectl -n CLUSTER_NAMESPACE edit cluster CLUSTER_NAME
Replace the following:
CLUSTER_NAMESPACE
: the namespace of the cluster.CLUSTER_NAME
: the name of the cluster.
Add the
maintenanceBlocks
section to the cluster configuration file to specify either a single IP address, or an address range, for nodes you want to put into maintenance mode.The following sample shows how to select multiple nodes by specifying a range of IP addresses:
metadata: name: my-cluster namespace: cluster-my-cluster spec: maintenanceBlocks: cidrBlocks: - 172.16.128.1-172.16.128.64
Save and apply the updated cluster configuration.
Google Distributed Cloud starts putting the nodes into maintenance mode.
Run the following command to get the status of the nodes in your cluster:
kubectl get nodes -n CLUSTER_NAME
The response is something like the following:
NAME STATUS ROLES AGE VERSION user-anthos-baremetal-01 Ready master 2d22h v1.17.8-gke.16 user-anthos-baremetal-04 Ready <none> 2d22h v1.17.8-gke.16 user-anthos-baremetal-05 Ready,SchedulingDisabled <none> 2d22h v1.17.8-gke.16 user-anthos-baremetal-06 Ready <none> 2d22h v1.17.8-gke.16
A status of
SchedulingDisabled
indicates that a node is in maintenance mode.Run the following command to get the number of nodes in maintenance mode:
kubectl get nodepools
The response should look something like the following output:
NAME READY RECONCILING STALLED UNDERMAINTENANCE UNKNOWN np1 3 0 0 1 0
This
UNDERMAINTENANCE
column in this sample shows that one node is in maintenance mode.Google Distributed Cloud also adds the following taints to nodes when they are put into maintenance mode:
baremetal.cluster.gke.io/maintenance:NoExecute
baremetal.cluster.gke.io/maintenance:NoSchedule
Steps to remove nodes from maintenance mode
To remove nodes from maintenance mode:
Edit the cluster configuration file to clear the nodes you want to remove from maintenance mode.
You can edit the configuration file with an editor of your choice, or you can edit the cluster custom resource directly by running the following command:
kubectl -n CLUSTER_NAMESPACE edit cluster CLUSTER_NAME
Replace the following:
CLUSTER_NAMESPACE
: the namespace of the cluster.CLUSTER_NAME
: the name of the cluster.
Either edit the IP addresses to remove specific nodes from maintenance mode or remove the
maintenanceBlocks
section remove all does from maintenance mode.Save and apply the updated cluster configuration.
Use
kubectl
commands to check the status of your nodes.