$ oc describe pod router-default-66d5cf9464-7pwkc
A node selector specifies a map of key-value pairs. The rules are defined using custom labels on nodes and selectors specified in pods.
For the pod to be eligible to run on a node, the pod must have the indicated key-value pairs as the label on the node.
If you are using node affinity and node selectors in the same pod configuration, see the important considerations below.
You can use node selectors on pods and labels on nodes to control where the pod is scheduled. With node selectors, OKD schedules the pods on nodes that contain matching labels.
You add labels to a node, a compute machine set, or a machine config. Adding the label to the compute machine set ensures that if the node or machine goes down, new nodes have the label. Labels added to a node or machine config do not persist if the node or machine goes down.
To add node selectors to an existing pod, add a node selector to the controlling object for that pod, such as a ReplicaSet
object, DaemonSet
object, StatefulSet
object, Deployment
object, or DeploymentConfig
object.
Any existing pods under that controlling object are recreated on a node with a matching label. If you are creating a new pod, you can add the node selector directly to the pod spec. If the pod does not have a controlling object, you must delete the pod, edit the pod spec, and recreate the pod.
You cannot add a node selector directly to an existing scheduled pod. |
To add a node selector to existing pods, determine the controlling object for that pod.
For example, the router-default-66d5cf9464-m2g75
pod is controlled by the router-default-66d5cf9464
replica set:
$ oc describe pod router-default-66d5cf9464-7pwkc
kind: Pod
apiVersion: v1
metadata:
# ...
Name: router-default-66d5cf9464-7pwkc
Namespace: openshift-ingress
# ...
Controlled By: ReplicaSet/router-default-66d5cf9464
# ...
The web console lists the controlling object under ownerReferences
in the pod YAML:
apiVersion: v1
kind: Pod
metadata:
name: router-default-66d5cf9464-7pwkc
# ...
ownerReferences:
- apiVersion: apps/v1
kind: ReplicaSet
name: router-default-66d5cf9464
uid: d81dd094-da26-11e9-a48a-128e7edf0312
controller: true
blockOwnerDeletion: true
# ...
Add labels to a node by using a compute machine set or editing the node directly:
Use a MachineSet
object to add labels to nodes managed by the compute machine set when a node is created:
Run the following command to add labels to a MachineSet
object:
$ oc patch MachineSet <name> --type='json' -p='[{"op":"add","path":"/spec/template/spec/metadata/labels", "value":{"<key>"="<value>","<key>"="<value>"}}]' -n openshift-machine-api
For example:
$ oc patch MachineSet abc612-msrtw-worker-us-east-1c --type='json' -p='[{"op":"add","path":"/spec/template/spec/metadata/labels", "value":{"type":"user-node","region":"east"}}]' -n openshift-machine-api
You can alternatively apply the following YAML to add labels to a compute machine set:
|
Verify that the labels are added to the MachineSet
object by using the oc edit
command:
For example:
$ oc edit MachineSet abc612-msrtw-worker-us-east-1c -n openshift-machine-api
MachineSet
objectapiVersion: machine.openshift.io/v1beta1
kind: MachineSet
# ...
spec:
# ...
template:
metadata:
# ...
spec:
metadata:
labels:
region: east
type: user-node
# ...
Add labels directly to a node:
Edit the Node
object for the node:
$ oc label nodes <name> <key>=<value>
For example, to label a node:
$ oc label nodes ip-10-0-142-25.ec2.internal type=user-node region=east
You can alternatively apply the following YAML to add labels to a node:
|
Verify that the labels are added to the node:
$ oc get nodes -l type=user-node,region=east
NAME STATUS ROLES AGE VERSION
ip-10-0-142-25.ec2.internal Ready worker 17m v1.31.3
Add the matching node selector to a pod:
To add a node selector to existing and future pods, add a node selector to the controlling object for the pods:
ReplicaSet
object with labelskind: ReplicaSet
apiVersion: apps/v1
metadata:
name: hello-node-6fbccf8d9
# ...
spec:
# ...
template:
metadata:
creationTimestamp: null
labels:
ingresscontroller.operator.openshift.io/deployment-ingresscontroller: default
pod-template-hash: 66d5cf9464
spec:
nodeSelector:
kubernetes.io/os: linux
node-role.kubernetes.io/worker: ''
type: user-node (1)
# ...
1 | Add the node selector. |
To add a node selector to a specific, new pod, add the selector to the Pod
object directly:
Pod
object with a node selectorapiVersion: v1
kind: Pod
metadata:
name: hello-node-6fbccf8d9
# ...
spec:
nodeSelector:
region: east
type: user-node
# ...
You cannot add a node selector directly to an existing scheduled pod. |