Filtering mechanisms for `incus_image` datasource

[jonatas-lima]

Some cloud image datasources provide filtering mechanisms, such as the most_recent and name_regex parameters in aws_ami or google_compute_instance. I reviewed the code and identified two possible approaches to implement this feature:

1. Client-side approach: Query all image aliases to Incus server, then apply the filters within the provider.

or

2. Server-side approach: Modify the Incus server image_alias to accept filtering parameters directly. Something like here.

Which approach do you think would be more appropriate?

If this issue seems relevant, I’d be happy to contribute by working on it!

[maveonair]

From a provider’s perspective, it’s always preferable to handle heavy work on the server-side. However, we already have logic in our provider that queries all aliases and determines the appropriate image. This is done, for example, when specifying the image’s architecture.

But if you need to query all possible image aliases first, it might not be the most efficient solution if an image server has many aliases. In such cases, it could make sense for the server to provide an API to leverage that functionality.

@stgraber what are your thoughts on this?

[stgraber]

Most Incus image servers are static web servers using simplestreams, so there is no way to add an API to that which would do server-side filtering.

We could do it in the Incus API but then that would only apply to the relatively uncommon case where Incus itself is used as an image server which is very unlikely for any environment where enough images are present to justify server-side filtering.