cluster upgrade validation fails if eks-a kubeconfig namespace is not 'default'

[swapzero]

What happened:

When using the same kubeconfig as the EKS-A tooling, running eksctl anywhere upgrade cluster with a namespace other than 'default' selected causes one of the checks to fail:

Error: failed to upgrade cluster: validations failed: getting eksa TinkerbellMachineConfig Error from server (NotFound): tinkerbellmachineconfigs.anywhere.eks.amazonaws.com "eks-a-cp" not found

It looks like one of the checks doesn't use --namespace in the kubectl command.

What you expected to happen:

The checks should pass regardless of the current namespace.

How to reproduce it (as minimally and precisely as possible):

This is easy to reproduce:

# use the same kubeconfig as EKS-A tooling
export KUBECONFIG=eks-a/eks-a-eks-a-cluster.kubeconfig

$ kubectl get nodes
NAME       STATUS   ROLES           AGE   VERSION
cplane-0   Ready    control-plane   35m   v1.31.9-eks-ca3410b
cplane-1   Ready    control-plane   31m   v1.31.9-eks-ca3410b
cplane-2   Ready    control-plane   25m   v1.31.9-eks-ca3410b
worker-0   Ready    <none>          17m   v1.31.9-eks-ca3410b
worker-1   Ready    <none>          17m   v1.31.9-eks-ca3410b

# switch the namespace to something else than default
$ kubens -c
default

$ kubens eksa-system
✔ Active namespace is "eksa-system"

$ kubens -c
eksa-system

# start an `upgrade cluster` without changing any settings in `cluster.yaml`
eksctl anywhere upgrade cluster --hardware-csv hardware.csv -f cluster.yaml --no-timeouts

Performing setup and validations
...
✅ Upgrade cluster worker node group kubernetes version increment
✅ Validate authentication for git provider
❌ Validation failed {"validation": "validate immutable fields", "error": "getting eksa TinkerbellMachineConfig Error from server (NotFound): tinkerbellmachineconfigs.anywhere.eks.amazonaws.com "eks-a-cp" not found\n", "remediation": ""}
✅ Validate cluster's eksaVersion matches EKS-Anywhere Version
✅ Validate eksa controller is not paused

---

This simple fix would be helpful if you want to build an automation around eksctl anywhere.

---

EKS Anywhere Release

$ eksctl anywhere version
Version: v0.22.6
Release Manifest URL: https://anywhere-assets.eks.amazonaws.com/releases/eks-a/manifest.yaml
Bundle Manifest URL: https://anywhere-assets.eks.amazonaws.com/releases/bundles/100/manifest.yaml