Cluster name has a stray "\n" character, messing up dashboard queries

[Leon]

It seems that the generated cluster name may contain and end-of-line character:
https://github.com/charmed-kubernetes/charm-kubernetes-control-plane/blob/da2725c67c44bcc855de166fc3251c28879498dd/src/charm.py#L418C9-L418C28

Not sure how it could happen, but on grafana we can clearly see this:

          "labels": {
            "__name__": "kube_pod_container_resource_requests",
            "cluster": "kubernetes-1er8ci1qdkk64gndu4n0b8trf7azivp8\n",
            "container": "calico-node",
            "exported_node": "m2",
            "instance": "localhost:6443",
            "job": "kube-state-metrics",

Also see screenshot.

This can be confirmed by querying prometheus directly:

$ curl 10.1.199.215:9090/api/v1/label/cluster/values
{"status":"success","data":["etcd-0","kubernetes-1er8ci1qdkk64gndu4n0b8trf7azivp8\n"]}

Reproducer is available here: https://pastebin.canonical.com/p/dqyx5TwFkx/

[Adam Dyess (addyess)]

I see no way of actually generating a LF or CR.

the method to create the clustername is

```
def token_generator(length=32):
    """Generate a random token for use in account tokens.

    param: length - the length of the token to generate
    """
    alpha = string.ascii_letters + string.digits
    token = "".join(random.SystemRandom().choice(alpha) for _ in range(length))
    return token
```

which limits the cluster name to be alphanumerics. After this call a further winnowing is done to push to lowercase.

Its more likely this comes from the upgrade where the cluster was stored in leader_set.

we should strip the output from leader_get here

https://github.com/charmed-kubernetes/charm-kubernetes-control-plane/blob/da2725c67c44bcc855de166fc3251c28879498dd/src/charm.py#L409-L410

[Adam Dyess (addyess)]

https://github.com/charmed-kubernetes/charm-kubernetes-control-plane/pull/347

[Adam Dyess (addyess)]

1.29 backport:
https://github.com/charmed-kubernetes/charm-kubernetes-control-plane/commit/f90e69a00ef0202a47240547dcdfdd3e2852c14c
1.30 backport:
https://github.com/charmed-kubernetes/charm-kubernetes-control-plane/commit/9523130355c0227a6271f345602d424e7f33c47b