The introduction of a heirarchical addressing scheme for providers gives
us an opportunity to make more explicit the special case of "built-in"
providers.
Thus far we've just had a special case in the "command" package that the
provider named "terraform" is handled differently than all others, though
there's nothing especially obvious about that in the UI.
Moving forward we'll put such "built-in" providers under the special
namespace terraform.io/builtin/terraform, which will be visible in the UI
as being different than the other providers and we can use the namespace
itself (rather than a particular name) as the trigger for our special-case
behaviors around built-in plugins.
We have no plans to introduce any built-in providers other than
"terraform" in the foreseeable future, so any others will produce an
error.
This commit just establishes the addressing convention, without making use
of it anywhere yet. Subsequent commits will make the provider installer
and resolver codepaths aware of it, replacing existing checks for the
provider just being called "terraform".
Just as with the old installer mechanism, our goal is that explicit
provider installation is the only way that new provider versions can be
selected.
To achieve that, we conclude each call to EnsureProviderVersions by
writing a selections lock file into the target directory. A later caller
can then recall the selections from that file by calling SelectedPackages,
which both ensures that it selects the same set of versions and also
verifies that the checksums recorded by the installer still match.
This new selections.json file has a different layout than our old
plugins.json lock file. Not only does it use a different hashing algorithm
than before, we also record explicitly which version of each provider
was selected. In the old model, we'd repeat normal discovery when
reloading the lock file and then fail with a confusing error message if
discovery happened to select a different version, but now we'll be able
to distinguish between a package that's gone missing since installation
(which could previously have then selected a different available version)
from a package that has been modified.
For the old-style provider cache directory model we hashed the individual
executable file for each provider. That's no longer appropriate because
we're giving each provider package a whole directory to itself where it
can potentially have many files.
This therefore introduces a new directory-oriented hashing algorithm, and
it's just using the Go Modules directory hashing algorithm directly
because that's already had its cross-platform quirks and other wrinkles
addressed during the Go Modules release process, and is now used
prolifically enough in Go codebases that breaking changes to the upstream
algorithm would be very expensive to the Go ecosystem.
This is also a bit of forward planning, anticipating that later we'll use
hashes in a top-level lock file intended to be checked in to user version
control, and then use those hashes also to verify packages _during_
installation, where we'd need to be able to hash unpacked zip files. The
Go Modules hashing algorithm is already implemented to consistently hash
both a zip file and an unpacked version of that zip file.
There's still a lot of work to do here around both the UX and the
follow-up steps that need to happen after installation completes, but this
is enough to faciliate some initial end-to-end testing of the new-style
install process.
We cannot evaluate expansion during validation, since the values may not
be known at that time.
Inject a nodeValidateModule, using the "Concrete" pattern used for other
node types during graph building. This node will always evaluate to a
single module instance, so that we have a valid context within which to
evaluate all sub resources.
Make the expansion logic easier to follow, keeping the evaluation and
registration local to switch cases. We don't validate anything between
count or for_each (config loading should handle that), and we don't need
to keep relying on the count == -1 sentinel value.
os.NewFile was called on file descriptors 3, 4, and 5 during every init,
in case this process happened to be running inside panicwrap. If the
runtime has already chosen one of these file descriptors to use
internally, starting polling on them can cause the runtime to crash.
Initialize the file descriptors lazily, only if we know that they belong
to us, after Wrapped is checked.
Replace the graphNodeRoot for the main graph with a nodeCloseModule for
the root module. USe a new transformer as well, so as to not change any
behavior of DynamicExpand graphs.
Closing out the root module like we do with sub modules means we no
longer need the OrphanResourceTransformer, or the NodeDestroyResource.
The old resource destroy logic has mostly moved into the instance nodes,
and the remaining resource node was just for cleanup, which need to be
done again by the module since there isn't always a NodeDestroyResource
to be evaluated.
The more-correct state caused a few tests to fail, which need to be
cleaned up to match the state without empty resource husks.
There is not one more non-dependent type to look for when pruning unused
values. This fixes the oversight, but still leaves the ugly concrete
type checking which we need to remove.
During plan, anything dependent on a module can connect to the module
expansion node, because all instance nodes are created during
DynamicExpand. During apply the instance nodes are created from the
diff, so we need a root module to terminate the logical module subgraph.
Besides providing an anchor for the completion of a module, the
nodeCloseModule can also be used to cleanup the orphan resource and
module placeholders in the state.
NodeDestroyResource does not require a provider, and to avoid this a
temporary GraphNodeNoProvider was used to differentiate it from other
resource nodes. We can now de-couple the destroy node from the abstract
resource which was adding the ProvidedBy method, and remove the
NoProvider method.
Terraform 0.13 will allow the installation of providers from various
sources. If a user updates their configuration to change the source of
an in-use provider (for example, if the provider namespace changes),
they will also need to update the state file accordingly.
This commit introduces a new `state replace-provider` subcommand which
supports this. All resources using the `from` provider will be updated
to use the `to` provider.
We've been using the models from the "moduledeps" package to represent our
provider dependencies everywhere since the idea of provider dependencies
was introduced in Terraform 0.10, but that model is not convenient to use
for any use-case other than the "terraform providers" command that needs
individual-module-level detail.
To make things easier for new codepaths working with the new-style
provider installer, here we introduce a new model type
getproviders.Requirements which is based on the type the new installer was
already taking as its input. We have new methods in the states, configs,
and earlyconfig packages to produce values of this type, and a helper
to merge Requirements together so we can combine config-derived and
state-derived requirements together during installation.
The advantage of this new model over the moduledeps one is that all of
recursive module walking is done up front and we produce a simple, flat
structure that is more convenient for the main use-cases of selecting
providers for installation and then finding providers in the local cache
to use them for other operations.
This new model is _not_ suitable for implementing "terraform providers"
because it does not retain module-specific requirement details. Therefore
we will likely keep using moduledeps for "terraform providers" for now,
and then possibly at a later time consider specializing the moduledeps
logic for only what "terraform providers" needs, because it seems to be
the only use-case that needs to retain that level of detail.
Martin Atkins