Deploying k-c-p in a jammy container errors on /etc/fstab not found

[Chris Johnston]

1.25/stable on a Jammy lxd container fails with:

2022-10-25 19:40:25 INFO unit.kubernetes-control-plane/0.juju-log server.go:316 kube-control:49: LXD detected, faking kernel params via bind mounts
2022-10-25 19:40:25 ERROR unit.kubernetes-control-plane/0.juju-log server.go:316 kube-control:49: Hook error:
Traceback (most recent call last):
  File "/var/lib/juju/agents/unit-kubernetes-control-plane-0/.venv/lib/python3.10/site-packages/charms/reactive/__init__.py", line 74, in main
    bus.dispatch(restricted=restricted_mode)
  File "/var/lib/juju/agents/unit-kubernetes-control-plane-0/.venv/lib/python3.10/site-packages/charms/reactive/bus.py", line 390, in dispatch
    _invoke(other_handlers)
  File "/var/lib/juju/agents/unit-kubernetes-control-plane-0/.venv/lib/python3.10/site-packages/charms/reactive/bus.py", line 359, in _invoke
    handler.invoke()
  File "/var/lib/juju/agents/unit-kubernetes-control-plane-0/.venv/lib/python3.10/site-packages/charms/reactive/bus.py", line 181, in invoke
    self._action(*args)
  File "/var/lib/juju/agents/unit-kubernetes-control-plane-0/charm/reactive/kubernetes_control_plane.py", line 3701, in configure_kubelet
    kubernetes_common.configure_kubelet(
  File "/var/lib/juju/agents/unit-kubernetes-control-plane-0/charm/lib/charms/layer/kubernetes_common.py", line 1115, in configure_kubelet
    workaround_lxd_kernel_params()
  File "/var/lib/juju/agents/unit-kubernetes-control-plane-0/charm/lib/charms/layer/kubernetes_common.py", line 1000, in workaround_lxd_kernel_params
    host.fstab_add(fake_param_path, real_param_path, "none", "bind")
  File "/var/lib/juju/agents/unit-kubernetes-control-plane-0/.venv/lib/python3.10/site-packages/charmhelpers/core/host.py", line 620, in fstab_add
    return Fstab.add(dev, mp, fs, options=options)
  File "/var/lib/juju/agents/unit-kubernetes-control-plane-0/.venv/lib/python3.10/site-packages/charmhelpers/core/fstab.py", line 130, in add
    return cls(path=path).add_entry(Fstab.Entry(device,
  File "/var/lib/juju/agents/unit-kubernetes-control-plane-0/.venv/lib/python3.10/site-packages/charmhelpers/core/fstab.py", line 63, in __init__
    super(Fstab, self).__init__(self._path, 'rb+')
FileNotFoundError: [Errno 2] No such file or directory: '/etc/fstab'

Code: https://github.com/charmed-kubernetes/layer-kubernetes-common/blob/main/lib/charms/layer/kubernetes_common.py#L976

[George Kraft (cynerva)]

PR: https://github.com/charmed-kubernetes/layer-kubernetes-common/pull/37