When running on the LXD Juju cloud provider with Juju 3.1 to 3.3:
```
juju deploy vault vault --model lxd-cloud/cell0-ovn-central --config auto-generate-root-ca-cert=true --config totally-unsecure-auto-unlock=true --channel 1.8/stable --num-units 1
juju deploy postgresql postgresql --model lxd-cloud/cell0-ovn-central --channel latest/stable --num-units 1
# Wait here
juju integrate vault:db postgresql:db --model lxd-cloud/cell0-ovn-central
```
Without sleeping for several minutes until vault reports `Unit is ready` before making the relation, the relation will fail with the error: `hook failed: "db-relation-changed" for postgresql:db
```
unit-vault-2: 21:39:56 INFO unit.vault/2.juju-log db:13: Reactive main running for hook db-relation-changed
unit-vault-2: 21:39:56 ERROR unit.vault/2.juju-log db:13: Unable to find implementation for relation: peers of vault-ha
unit-vault-2: 21:39:56 INFO unit.vault/2.juju-log db:13: Initializing Leadership Layer (is leader)
unit-vault-2: 21:39:56 INFO unit.vault/2.juju-log db:13: Initializing Snap Layer
unit-vault-2: 21:39:56 INFO unit.vault/2.juju-log db:13: Invoking reactive handler: reactive/vault_handlers.py:260:configure_vault_psql
unit-vault-2: 21:39:56 INFO unit.vault/2.juju-log db:13: Invoking reactive handler: reactive/vault_handlers.py:348:request_db
unit-vault-2: 21:39:56 INFO unit.vault/2.juju-log db:13: Invoking reactive handler: reactive/vault_handlers.py:737:prime_assess_status
unit-vault-2: 21:39:56 INFO unit.vault/2.juju-log db:13: Invoking reactive handler: reactive/vault_handlers.py:1165:tune_pki_backend_config_changed
unit-vault-2: 21:39:56 ERROR unit.vault/2.juju-log db:13: Hook error:
Traceback (most recent call last):
File "/var/lib/juju/agents/unit-vault-2/.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-vault-2/.venv/lib/python3.10/site-packages/charms/reactive/bus.py", line 390, in dispatch
_invoke(other_handlers)
File "/var/lib/juju/agents/unit-vault-2/.venv/lib/python3.10/site-packages/charms/reactive/bus.py", line 359, in _invoke
handler.invoke()
File "/var/lib/juju/agents/unit-vault-2/.venv/lib/python3.10/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 1188, in tune_pki_backend_config_changed
vault_pki.update_roles(max_ttl=max_ttl)
File "/var/lib/juju/agents/unit-vault-2/charm/lib/charm/vault_pki.py", line 361, in update_roles
local = client.secrets.pki.read_role(
File "/var/lib/juju/agents/unit-vault-2/.venv/lib/python3.10/site-packages/hvac/api/secrets_engines/pki.py", line 467, in read_role
return self._adapter.get(
File "/var/lib/juju/agents/unit-vault-2/.venv/lib/python3.10/site-packages/hvac/adapters.py", line 113, in get
return self.request("get", url, **kwargs)
File "/var/lib/juju/agents/unit-vault-2/.venv/lib/python3.10/site-packages/hvac/adapters.py", line 364, in request
response = super(JSONAdapter, self).request(*args, **kwargs)
File "/var/lib/juju/agents/unit-vault-2/.venv/lib/python3.10/site-packages/hvac/adapters.py", line 330, in request
utils.raise_for_error(
File "/var/lib/juju/agents/unit-vault-2/.venv/lib/python3.10/site-packages/hvac/utils.py", line 43, in raise_for_error
raise exceptions.InvalidPath(message, errors=errors, method=method, url=url)
hvac.exceptions.InvalidPath: no handler for route 'charm-pki-local/roles/local', on get http://127.0.0.1:8220/v1/charm-pki-local/roles/local
```
Additionally, this also happens if you try to make 2 simultaneous relations to vault, even if you wait until all charms are happy by sleeping for 15 mins first.
```
juju deploy postgresql postgresql --model lxd-cloud/
juju deploy vault vault --model lxd-cloud/
juju deploy ovn-central ovn-central --model lxd-cloud/
# A long 15 minute sleep here
juju integrate ovn-central:
juju integrate vault:db postgresql:db --model lxd-cloud/
```