57 lines
2.1 KiB
ReStructuredText
57 lines
2.1 KiB
ReStructuredText
=============================
|
|
How-To Write a config context
|
|
=============================
|
|
|
|
A config context is an additional context that is passed to the template
|
|
renderer in its own namespace. They are usually useful when some logic
|
|
needs to be applied to user supplied charm configuration. The context
|
|
has access to the charm object.
|
|
|
|
Below is an example which applies logic to the charm config as well as
|
|
collecting the application name to construct the context.
|
|
|
|
.. code:: python
|
|
|
|
class CinderCephConfigurationContext(ConfigContext):
|
|
"""Cinder Ceph configuration context."""
|
|
|
|
def context(self) -> None:
|
|
"""Cinder Ceph configuration context."""
|
|
config = self.charm.model.config.get
|
|
data_pool_name = config('rbd-pool-name') or self.charm.app.name
|
|
if config('pool-type') == "erasure-coded":
|
|
pool_name = (
|
|
config('ec-rbd-metadata-pool') or
|
|
f"{data_pool_name}-metadata"
|
|
)
|
|
else:
|
|
pool_name = data_pool_name
|
|
backend_name = config('volume-backend-name') or self.charm.app.name
|
|
return {
|
|
'cluster_name': self.charm.app.name,
|
|
'rbd_pool': pool_name,
|
|
'rbd_user': self.charm.app.name,
|
|
'backend_name': backend_name,
|
|
'backend_availability_zone': config('backend-availability-zone'),
|
|
}
|
|
|
|
Configuring Charm to use custom config context
|
|
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
|
|
|
|
The charm can append the new context onto those provided by the base class.
|
|
|
|
.. code:: python
|
|
|
|
import ops_sunbeam.charm as sunbeam_charm
|
|
|
|
class MyCharm(sunbeam_charm.OSBaseOperatorAPICharm):
|
|
"""Charm the service."""
|
|
|
|
@property
|
|
def config_contexts(self) -> List[sunbeam_ctxts.ConfigContext]:
|
|
"""Configuration contexts for the operator."""
|
|
contexts = super().config_contexts
|
|
contexts.append(
|
|
sunbeam_ctxts.CinderCephConfigurationContext(self, "cinder_ceph"))
|
|
return contexts
|