Although we tend to return these in contexts where at least one of these
values is implied, being explicit means that PackageMeta values are
self-contained and less reliant on such external context.
Registries backed by static files are likely to use relative paths to
their archives for simplicity's sake, but we'll normalize them to be
absolute before returning because the caller wouldn't otherwise know what
to resolve the URLs relative to.
We intend to support installation both directly from origin registries and
from mirrors in the local filesystem or over the network. This Source
interface will serve as our abstraction over those three options, allowing
calling code to treat them all the same.
Our existing provider installer was originally built to work with
releases.hashicorp.com and later retrofitted to talk to the official
Terraform Registry. It also assumes a flat namespace of providers.
We're starting a new one here, copying and adapting code from the old one
as necessary, so that we can build out this new API while retaining all
of the existing functionality and then cut over to this new implementation
in a later step.
Here we're creating a foundational component for the new installer, which
is a mechanism to query for the available versions and download locations
of a particular provider.
Subsequent commits in this package will introduce other Source
implementations for installing from network and filesystem mirrors.
Martin Atkins