openshift-dns pod placement can cause intermittent DNS resolution failures
Issue
openshift-dns
pods are deployed via a Daemonset
. In OpenShift 4.4.x they did not tolerate the NoSchedule
taint
placed on nodes.
However, in OpenShift 4.5.x the pods are now deployed with the operator: "Exists" toleration
which tolerates taints
placed on nodes and can allow pods to be scheduled onto the nodes that have taints
.
In deployments with active/active LACP bonds and workloads that utilize SR-IOV (e.g., the F5 BigIP Load balancer), local traffic from a pod towards the SR-IOV VF is dropped by the switching infrastructure. Thus, if openshift-dns
pods are scheduled onto the load balancer node, traffic from the dns pod to the load balancer will be impacted.
This causes intermittent DNS queries failures.
Environment
- Red Hat OpenShift Container Platform
- 4.5
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