Create a single transformer to remove all unused nodes from the apply
graph. This is similar to the combination of the resource pruning done
in the destroy edge transformer, and the unused values transformer. In
addition to resources, variables, locals, and outputs, we now need to
remove unused module expansion nodes as well. Since these can all be
interdependent, we need to process them as whole in a single
transformation.
NodeModuleRemoved is redundant now with the concept of
nodeCloseModule, so we can replace it within the graph. This does mean
that nodeCloseModule needs to know if it's evaluating an orphaned module
that can't be expanded, but the overhead to checking this isn't too
bad.
Now that nodeModuleClose is referenceable, and we can ensure it's always
in the graph at the correct time, we can eliminate the need to connect
each resource to every single node within a module it references, and
instead connect only to the nodeModuleClose, which acts as the module
root. Since module expansion can cause exponential growth in the number
of edges in graphs, this will help with performance problems when
transforming and reducing these graphs by eliminating the bulk of
redundant edges. This will also help with general debugging, making the
graphs easier to read.
Due to how often the state and plan types are referenced throughout
Terraform, there isn't a great way to switch them out gradually. As a
consequence, this huge commit gets us from the old world to a _compilable_
new world, but still has a large number of known test failures due to
key functionality being stubbed out.
The stubs here are for anything that interacts with providers, since we
now need to do the follow-up work to similarly replace the old
terraform.ResourceProvider interface with its replacement in the new
"providers" package. That work, along with work to fix the remaining
failing tests, will follow in subsequent commits.
The aim here was to replace all references to terraform.State and its
downstream types with states.State, terraform.Plan with plans.Plan,
state.State with statemgr.State, and switch to the new implementations of
the state and plan file formats. However, due to the number of times those
types are used, this also ended up affecting numerous other parts of core
such as terraform.Hook, the backend.Backend interface, and most of the CLI
commands.
Just as with 5861dbf3fc49b19587a31816eb06f511ab861bb4 before, I apologize
in advance to the person who inevitably just found this huge commit while
spelunking through the commit history.
Due to how deeply the configuration types go into Terraform Core, there
isn't a great way to switch out to HCL2 gradually. As a consequence, this
huge commit gets us from the old state to a _compilable_ new state, but
does not yet attempt to fix any tests and has a number of known missing
parts and bugs. We will continue to iterate on this in forthcoming
commits, heading back towards passing tests and making Terraform
fully-functional again.
The three main goals here are:
- Use the configuration models from the "configs" package instead of the
older models in the "config" package, which is now deprecated and
preserved only to help us write our migration tool.
- Do expression inspection and evaluation using the functionality of the
new "lang" package, instead of the Interpolator type and related
functionality in the main "terraform" package.
- Represent addresses of various objects using types in the addrs package,
rather than hand-constructed strings. This is not critical to support
the above, but was a big help during the implementation of these other
points since it made it much more explicit what kind of address is
expected in each context.
Since our new packages are built to accommodate some future planned
features that are not yet implemented (e.g. the "for_each" argument on
resources, "count"/"for_each" on modules), and since there's still a fair
amount of functionality still using old-style APIs, there is a moderate
amount of shimming here to connect new assumptions with old, hopefully in
a way that makes it easier to find and eliminate these shims later.
I apologize in advance to the person who inevitably just found this huge
commit while spelunking through the commit history.
Remove the module entry from the state if a module is no longer in the
configuration. Modules are not removed if there are any existing
resources with the module path as a prefix. The only time this should be
the case is if a module was removed in the config, but the apply didn't
target that module.
Create a NodeModuleRemoved and an associated EvalDeleteModule to track
the module in the graph then remove it from the state. The
NodeModuleRemoved dependencies are simply any other node which contains
the module path as a prefix in its path.
This could have probably been done much easier as a step in pruning the
state, but modules are going to have to be promoted to full graph nodes
anyway in order to support count.
James Bardin