This is not tested yet, but it's a compilable strawman implementation of
the necessary sequence of events to coordinate all of the moving parts
of running a provider installation operation.
This will inevitably see more iteration in later commits as we complete
the surrounding parts and wire it up to be used by "terraform init". So
far, it's just dead code not called by any other package.
The Installer type will encapsulate the logic for running an entire
provider installation request: given a set of providers to install, it
will determine a method to obtain each of them (or detect that they are
already installed) and then take the necessary actions.
So far it doesn't do anything, but this stubs out an interface by which
the caller can request ongoing notifications during an installation
operation.
The existing functionality in this package deals with finding packages
that are either available for installation or already installed. In order
to support installation we also need to determine the location where a
package should be installed.
This lives in the getproviders package because that way all of the logic
related to the filesystem layout for local provider directories lives
together here where they can be maintained together more easily in future.
This is a basic implementation of FilesystemMirrorSource for now aimed
only at the specific use-case of scanning the cache of provider plugins
Terraform will keep under the ".terraform" directory, as part of our
interim provider installer implementation for Terraform 0.13.
The full functionality of this will grow out in later work when we
implement explicit local filesystem mirrors, but for now the goal is to
use this just to inspect the work done by the automatic installer once
we switch it to the new provider-FQN-aware directory structure.
The various FIXME comments in this are justified by the limited intended
scope of this initial implementation, and they should be resolved by
later work to use FilesystemMirrorSource explicitly for user-specified
provider package mirrors.
These are utility functions to ease processing of lists of PackageMeta
elsewhere, once we have functionality that works with multiple packages
at once. The local filesystem mirror source will be the first example of
this, so these methods are motivated mainly by its needs.
This is just to have a centralized set of logic for converting from a
platform string (like "linux_amd64") to a Platform object, so we can do
normalization and validation consistently.
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.
Our local filesystem mirror mechanism will allow provider packages to be
given either in packed form as an archive directly downloaded to disk or
in an unpacked form where the archive is extracted.
Distinguishing these two cases in the concrete Location types will allow
callers to reliably select the mode chosen by the selected installation
source and handle it appropriately, rather than resorting to out-of-band
heuristics like checking whether the object is a directory or a file.
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