🐛 create bootstrap token if not found in refresh process

[archerwu9425]

What this PR does / why we need it:
For the refreshBootstrapTokenIfNeeded function, if token not found, should create a new one instead of just raise error

why we need it:

1. Bootstrap token is created by bootstrap controller but will delete by workload-cluster
2. MachinePool is scaled up/down by cluster autoscaler
3. When cluster is with paused: true filed, reconcile will stop. During this period, bootstrap token may be deleted but kubeadminconfig will not updated.
4. Instanced in machinepool created during this period will not be able to join cluster, even after cluster remove paused filed and start to reconcile.

Which issue(s) this PR fixes (optional, in fixes #<issue number>(, fixes #<issue_number>, ...) format, will close the issue(s) when PR gets merged):
Fixes #11034

[k8s-ci-robot]

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[k8s-ci-robot]

Hi @archerwu9425. Thanks for your PR.

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[archerwu9425]

/area bootstrap

[neolit123]

seems like this creates a "secret" (bootstrap-token) on demand. i.e. when the user is trying to join node with some invalid BST, the BST will be created for them.
that doesn't seem like the correct thing to do, but interesting to hear more opinions.

[archerwu9425]

seems like this creates a "secret" (bootstrap-token) on demand. i.e. when the user is trying to join node with some invalid BST, the BST will be created for them.

that doesn't seem like the correct thing to do, but interesting to hear more opinions.

If the token kept in kubeadminconfig is not able to find in remote cluster, it will create a new one and update the token in kubeadminconfig and launch template. This will still be handled by bootstrap controller and used for machine pool. Also this is the logic for rotate machine pool bootstrap token, the only difference is the machine pool has nodeRef or not, code block to be referred:

https://github.com/kubernetes-sigs/cluster-api/blob/main/bootstrap/kubeadm/internal/controllers/kubeadmconfig_controller.go#L276-L286

https://github.com/kubernetes-sigs/cluster-api/blob/main/bootstrap/kubeadm/internal/controllers/kubeadmconfig_controller.go#L379-L391

[archerwu9425]

@neolit123 @ncdc @greut Could you please help review? Thanks

[neolit123]

seems like this creates a "secret" (bootstrap-token) on demand. i.e. when the user is trying to join node with some invalid BST, the BST will be created for them. that doesn't seem like the correct thing to do, but interesting to hear more opinions.

my comment is here. waiting for comments from more maintainers.