Support for loading file resources by filename

[lucistanescu]

Requirements

Referencing Matrix conversation: https://matrix.to/#/!xzmWHtGpPfVCXKivIh:ubuntu.com/$Pcyf0Dv5amrKGRLYbUagW1ObipX-CFfOcjhLj1jnUQ4?via=ubuntu.com&via=matrix.org&via=canonical.com

Juju supports specifying a file resource by filename: `juju deploy --resource foo=./bar.moo my-charm`. This seemed appropriate for passing a rather large file to a charm, instead of using configuration options.

However, the juju terraform provider does not support that, requiring a revision to be specified. Is it possible to add support for specifying a file resource by filename?

On the other hand, having the contents of the file as part of the terraform state is useful, as the remote state would be updated whenever the file contents change.

Urgency

It would save from a weird workaround

Notes & References

I've also found the following PR: #493. @hmlanigan mentioned that:

We will only be allowing revision number and oci-image information be used. We will not support custom files to be uploaded.

and

It also muddies the water around uploading file resources which we do not intend to support.

This suggests that this functionality may not be intended. Is that indeed the case? What is the right approach for the problem I had described previously (passing a rather large configuration file to the charm from the terraform plan).

[alesstimec]

I would suggest that using resources to pass configuration files to the charm is wrong. If there is no way around it, you could modify the charm to pull the config file from a publicly accessible location instead of using charm resources.

For now there is no plan to support local resources as we do not support local charms.