This changes the approach used by the provider installer to remember
between runs which selections it has previously made, using the lock file
format implemented in internal/depsfile.
This means that version constraints in the configuration are considered
only for providers we've not seen before or when -upgrade mode is active.
These are helper functions to give the installation UI some hints about
whether the lock file has changed so that it can in turn give the user
advice about it. The UI-layer callers of these will follow in a later
commit.
The logic for what constitutes a valid hash and how different hash schemes
are represented was starting to get sprawled over many different files and
packages.
Consistently with other cases where we've used named types to gather the
definition of a particular string into a single place and have the Go
compiler help us use it properly, this introduces both getproviders.Hash
representing a hash value and getproviders.HashScheme representing the
idea of a particular hash scheme.
Most of this changeset is updating existing uses of primitive strings to
uses of getproviders.Hash. The new type definitions are in
internal/getproviders/hash.go.
Although origin registries return specific [filename, hash] pairs, our
various different installation methods can't produce a structured mapping
from platform to hash without breaking changes.
Therefore, as a compromise, we'll continue to do platform-specific checks
against upstream data in the cases where that's possible (installation
from origin registry or network mirror) but we'll treat the lock file as
just a flat set of equally-valid hashes, at least one of which must match
after we've completed whatever checks we've made against the
upstream-provided checksums/signatures.
This includes only the minimal internal/getproviders updates required to
make this compile. A subsequent commit will update that package to
actually support the idea of verifying against multiple hashes.
It doesn't make sense for a built-in provider to appear in a lock file
because built-in providers have no version independent of the version of
Terraform they are compiled into.
We also exclude legacy providers here, because they were supported only
as a transitional aid to enable the Terraform 0.13 upgrade process and
are not intended for explicit selection.
The provider installer will, once it's updated to understand dependency
locking, use this concept to decide which subset of its selections to
record in the dependency lock file for reference for future installation
requests.
This is an initial implementation of writing locks back to a file on disk.
This initial implementation is incomplete because it does not write the
changes to the new file atomically. We'll revisit that in a later commit
as we return to polish these codepaths, once we've proven out this
package's design by integrating it with Terraform's provider installer.
This is the initial implementation of the parser/decoder portion of the
new dependency lock file handler. It's currently dead code because the
caller isn't written yet. We'll continue to build out this functionality
here until we have the basic level of both load and save functionality
before introducing this into the provider installer codepath.
Martin Atkins