Failed Charmed Worker Deployment Due To Tag Error on GCP

[Eslam Nawara]

The Juju GCP deployment fails for both of Kubernetes cluster core and Charmed distribution due to tagging error in GCP. The code tries to tag the instances using an incompatible syntax as it uses special character.

Here's the error that shows up on the worker and integrator node.
ERROR unit.gcp-integrator/0.juju-log Traceback (most recent call last):
  File "/var/lib/juju/agents/unit-gcp-integrator-0/charm/reactive/gcp.py", line 68, in handle_requests
    request.instance_labels)
  File "lib/charms/layer/gcp.py", line 125, in label_instance
    '--labels', ','.join('='.join([k, v]) for k, v in labels.items()))
  File "lib/charms/layer/gcp.py", line 253, in _gcloud
    raise GCPError(stderr)
charms.layer.gcp.GCPError: ERROR: (gcloud.compute.instances.add-labels) HTTPError 400: Invalid value for field 'labels': ''. Label key 'juju.io/az' violates format constraints. The key must start with a lowercase character, can only contain lowercase letters, numeric characters, underscores and dashes. The key can be at most 63 characters long. International characters are allowed.

This the the GitHub commit that introduced this bug
https://github.com/charmed-kubernetes/charm-kubernetes-worker/commit/cb3d6a53c8e932b8a583587ea8abf3c6bee21a63

[Cory Johns (johnsca)]

https://github.com/charmed-kubernetes/charm-kubernetes-worker/pull/8

[Tim Van Steenburgh (tvansteenburgh)]

Fix available in kubernetes-worker-527 or later.

[George Kraft (cynerva)]

PR to stable branch: https://github.com/charmed-kubernetes/charm-kubernetes-worker/pull/14