Use the correct hostname in kubelet's kubeconfig

[anton-johansson]

Closes #22

There was a mix of hostvars[item].inventory_hostname and inventory_hostname in a task that had run_once: True, causing it to give all nodes the hostname of the first node in the credentials part of kubeconfig.

Here's an example kubeconfig of my k8s-worker-02 before this fix:

apiVersion: v1
clusters:
- cluster:
    certificate-authority-data: <redacted>
    server: https://k8s-master-01:6443
  name: kubernetes
contexts:
- context:
    cluster: kubernetes
    user: system:node:k8s-worker-02
  name: default
current-context: default
kind: Config
preferences: {}
users:
- name: system:node:k8s-worker-01
  user:
    client-certificate-data: <redacted>
    client-key-data: <redacted>

[amimof]

The run_once statement was added because kubectl config-commands would sometimes fail due to a lock-file already being present. Kubectl only lets one process modify kubeconfigs and having multiple nodes would cause an error because it runs on localhost.

I suggest adding the kubectl role to to masters and nodes groups and let each host create their kubeconfig rather than delegating it to localhost and copying them over.

[anton-johansson]

Yeah, that sounds like a better idea, indeed!

Could feel a bit redundant to have kubectl on the nodes and masters though?

[amimof]

That means that installing kubectl on localhost isn't necessary anymore and requires adding additional instructions in README. I'll make some changes and push to this branch to see how it looks.

[amimof]

I haven't tried the latest commit, but now when we don't have with_items anymore, shouldn't {{ hostvars[item].inventory_hostname }} be replaced with {{ inventory_hostname }}?

Yes it does. I will change that :)

[amimof]

@anton-johansson Have you had the chance to test the latest commit?

[anton-johansson]

No, I can do that now.

[anton-johansson]

Other than my issue in #25 (which isn't really related to this PR), this works as expected. I really dig the change where we got rid of kubectl alltogether and used templates instead. Feels better!

One thing though. Is the kubectl role necessary at all anymore?

[amimof]

Not really, but it's necessary on localhost until i figure out how to replace it and update the README with instructions since your default ~/.kube/config won't be ready for your new cluster after an install.

[anton-johansson]

Ah of course. But it might not be a bad idea to keep it on localhost then? Quite nice to get a ready ~/.kube/config. :)