### SPIKE: Specific workloads on Specific Nodes
JIRA: [link](https://projects.engineering.redhat.com/browse/CPE-702)
Resources:
* [1] Advanced pod scheduling [https://docs.openshift.com/container-platform/4.4/nodes/scheduling/nodes-scheduler-about.html](https://docs.openshift.com/container-platform/4.4/nodes/scheduling/nodes-scheduler-about.html)
* [2] Pod placing using node affinity rules [https://docs.openshift.com/container-platform/4.4/nodes/scheduling/nodes-scheduler-node-affinity.html](https://docs.openshift.com/container-platform/4.4/nodes/scheduling/nodes-scheduler-node-affinity.html)
* [3] Pod placing using node taints, and pod tolerations [https://docs.openshift.com/container-platform/4.4/nodes/scheduling/nodes-scheduler-taints-tolerations.html](https://docs.openshift.com/container-platform/4.4/nodes/scheduling/nodes-scheduler-taints-tolerations.html)
* [4] Pod affinity/anti-affinity [https://docs.openshift.com/container-platform/4.4/nodes/scheduling/nodes-scheduler-pod-affinity.html#nodes-scheduler-pod-affinity](https://docs.openshift.com/container-platform/4.4/nodes/scheduling/nodes-scheduler-pod-affinity.html#nodes-scheduler-pod-affinity)
* [5] Cluster/Project wide Node Affinity [https://docs.openshift.com/container-platform/4.4/nodes/scheduling/nodes-scheduler-node-selectors.html#nodes-scheduler-node-selectors-project_nodes-scheduler-node-selectors](https://docs.openshift.com/container-platform/4.4/nodes/scheduling/nodes-scheduler-node-selectors.html#nodes-scheduler-node-selectors-project_nodes-scheduler-node-selectors)
* [6] Cluster [https://github.com/storageos/cluster-operator](https://github.com/storageos/cluster-operator)
I’m thinking we should go with a mixture of two modes, taint/toleration and node affinity in order to target a specific class of compute node with privileged network access and ensure only specific workloads may be scheduled there, and so access them.
Creating a POC:
Steps:
```
oc new-project targeting-specific-nodes
oc get nodes
NAME STATUS ROLES AGE VERSION
kempty-n10.ci.centos.org Ready worker 7d5h v1.17.1
kempty-n11.ci.centos.org Ready worker 7d5h v1.17.1
kempty-n12.ci.centos.org Ready worker 7d5h v1.17.1
kempty-n6.ci.centos.org Ready master 7d5h v1.17.1
kempty-n7.ci.centos.org Ready master 7d5h v1.17.1
kempty-n8.ci.centos.org Ready master 7d5h v1.17.1
kempty-n9.ci.centos.org Ready worker 7d5h v1.17.1
oc adm taint nodes kempty-n9.ci.centos.org examplekey=examplevalue:NoSchedule
oc label node kempty-n9.ci.centos.org examplekey=examplevalue
oc get node kempty-n9.ci.centos.org -o yaml
…
labels:
...
examplekey: examplevalue
...
...
spec:
taints:
- effect: NoSchedule
key: examplekey
value: examplevalue
…
oc apply -f targetspecificnodes.yaml
oc get pods --all-namespaces -o wide | grep kempty-n9
...
targeting-specific-nodes example-57d74cf6b4-mlppz 1/1 Running 0 13s 10.130.2.15 kempty-n9.ci.centos.org <none> <none>
targeting-specific-nodes example-57d74cf6b4-sgnzh 1/1 Running 0 13s 10.130.2.17 kempty-n9.ci.centos.org <none> <none>
targeting-specific-nodes example-57d74cf6b4-swllc 1/1 Running 0 13s 10.130.2.16 kempty-n9.ci.centos.org <none> <none>
...
```