[Release-1.31] - Add a topologySpreadConstraint with `topology.kubernetes.io/zone` key to CoreDNS manifest

[brandond]

Backport fix for Add a topologySpreadConstraint with topology.kubernetes.io/zone key to CoreDNS manifest

• Add a topologySpreadConstraint with topology.kubernetes.io/zone key to CoreDNS manifest #12433

[fmoral2]

Validated on Version:

-$ k3s version v1.31.9+k3s-5f094d69 (5f094d69)
 

Environment Details

Infrastructure
Cloud EC2 instance

Node(s) CPU architecture, OS, and Version:
rhel 9.5
AMD

Cluster Configuration:
2 nodes

Steps to validate the fix

1. Install k3s
2. scale coredns deployment to 8 replicas
3. Label nodes with topology.kubernetes.io/zone
4. Validate that pods are distributed across nodes based on the zone label
5. Validate that pods are distributed across nodes based on the topologyKey label
6. Validate that the topologyKey label is set to topology.kubernetes.io/zone in the coredns deployment

Reproduction Issue:

Details

  

 
~$ kubectl get deployment coredns -n kube-system -o yaml | grep topologyKey
        topologyKey: kubernetes.io/hostname
 

Validation Results:

   




  ~$curl -sfL https://get.k3s.io | INSTALL_K3S_COMMIT=5f094d699a1c68924de2f20e619621a7159d3506  INSTALL_K3S_CHANNEL=latest sh -s - server  --write-kubeconfig-mode 644 --token test


 ~$ kubectl get deployment coredns -n kube-system -o yaml | grep topologyKey
        topologyKey: kubernetes.io/hostname
        topologyKey: topology.kubernetes.io/zone



 ~$ kubectl label node  ip-1   topology.kubernetes.io/zone=us-east-2b --overwrite

 ~$ kubectl label node  ip-2  topology.kubernetes.io/zone=us-east-2a --overwrite
 
 $ kubectl get nodes -L topology.kubernetes.io/zone
NAME               STATUS   ROLES                  AGE   VERSION                ZONE
ip-1               Ready    <none>                 40s   v1.33.1+k3s-5f094d69   us-east-2b
ip-2               Ready    control-plane,master   31m   v1.33.1+k3s-5f094d69   us-east-2a



 

~$ kubectl scale deployment coredns -n kube-system --replicas=8
deployment.apps/coredns scaled

 Pod: coredns-5688667fd4-2cn6b -> Node: ip-1     -> Zone: us-east-2a
Pod: coredns-5688667fd4-6lb2c -> Node: ip-2        -> Zone: us-east-2b
Pod: coredns-5688667fd4-fj8mz -> Node: ip-2        -> Zone: us-east-2b
Pod: coredns-5688667fd4-hbd78 -> Node: ip-1        -> Zone: us-east-2a
Pod: coredns-5688667fd4-hg75l -> Node: ip-1        -> Zone: us-east-2a
Pod: coredns-5688667fd4-kldrz -> Node: ip-2        -> Zone: us-east-2b
Pod: coredns-5688667fd4-kzzdn -> Node: ip-1        -> Zone: us-east-2a
Pod: coredns-5688667fd4-nzjml -> Node: ip-2        -> Zone: us-east-2b