[Feature Request] Add a "ca-certificates-path" to cloud definition files for easier headless operation on OpenStack or other private clouds

Juju allows addition of clouds using a cloud definition file while executing juju add-cloud. For many private clouds a self-signed CA is used and as a result we need to pass in a certificate during this to ensure the Juju agent can auth against the cloud. Today we do this using the “ca-certificates” key and pasting the contents of the CA into the definition file. Pasting in the contents of the CA can be problematic however for headless operation of juju add-cloud such as in the case of a CI pipeline.

Ideally we would be able to pass a path to a certificate file into the definition to make building that file more simple. This would also bring the cloud definition file into feature parity with some of the interactive prompts, such as that of the OpenStack add-cloud.

We support certificates from a path in several other cases (ca-cert and ca-cert-path for supplying the Juju controller certificate).

I think this is reasonable and not very hard to do, it does mean that your cloud definition won’t support older versions of Juju, but it certainly makes the definition easier to put together.