Comment 1 for bug 1904431

we've seen this during the certificates-relation-changed hook as well:

Traceback (most recent call last):
  File "/var/lib/juju/agents/unit-vault-2/.venv/lib/python3.8/site-packages/charms/reactive/__init__.py", line 74, in main
    bus.dispatch(restricted=restricted_mode)
  File "/var/lib/juju/agents/unit-vault-2/.venv/lib/python3.8/site-packages/charms/reactive/bus.py", line 390, in dispatch
    _invoke(other_handlers)
  File "/var/lib/juju/agents/unit-vault-2/.venv/lib/python3.8/site-packages/charms/reactive/bus.py", line 359, in _invoke
    handler.invoke()
  File "/var/lib/juju/agents/unit-vault-2/.venv/lib/python3.8/site-packages/charms/reactive/bus.py", line 181, in invoke
    self._action(*args)
  File "/var/lib/juju/agents/unit-vault-2/charm/reactive/vault_handlers.py", line 861, in publish_ca_info
    chain = vault_pki.get_chain()
  File "/var/lib/juju/agents/unit-vault-2/charm/lib/charm/vault_pki.py", line 80, in get_chain
    return client.read('{}/cert/ca_chain'.format(name))['data']['certificate']
  File "/var/lib/juju/agents/unit-vault-2/.venv/lib/python3.8/site-packages/hvac/v1/__init__.py", line 157, in read
    return self._adapter.get('/v1/{0}'.format(path), wrap_ttl=wrap_ttl).json()
  File "/var/lib/juju/agents/unit-vault-2/.venv/lib/python3.8/site-packages/hvac/adapters.py", line 90, in get
    return self.request('get', url, **kwargs)
  File "/var/lib/juju/agents/unit-vault-2/.venv/lib/python3.8/site-packages/hvac/adapters.py", line 233, in request
    utils.raise_for_error(response.status_code, text, errors=errors)
  File "/var/lib/juju/agents/unit-vault-2/.venv/lib/python3.8/site-packages/hvac/utils.py", line 39, in raise_for_error
    raise exceptions.InternalServerError(message, errors=errors)
hvac.exceptions.InternalServerError: context deadline exceeded

coming from vault2 in this crashdump:
https://oil-jenkins.canonical.com/artifacts/e9741061-8c3b-42ef-95a9-c8fdd425245b/generated/generated/kubernetes/juju-crashdump-kubernetes-2021-05-02-01.11.52.tar.gz