This introduces a new GraphNode, GraphNodeExecutable, which will
gradually replace GraphNodeEvalable as part of the overall removal of
EvalTree()s. Terraform's Graph.walk function will now check if a node is
GraphNodeExecutable and run walker.Execute instead of running through
the EvalTree() and Eval().
For the time being, terraform will panic if a node implements both
GraphNodeExecutable and GraphNodeEvalable. This will be removed when
we've finished removing all GraphNodeEvalable implementations.
The new GraphWalker function, Execute(), is meant to replace both
EnterEvalTree and ExitEvalTree, and wraps the call to the
GraphNodeExecutable's Execute function.
As the Graph is walked, the current way to set the context path was to
have the walker return a context from EnterPath. This required that
every node know it's absolute path, which can no longer be the case
during plan when modules have not been expanded.
This introduces a new method called WithPath, which returns a copy of
the context with the internal path updated to reflect the method
argument. Any use of the EvalContext that requires knowing the path will
now panic if it wasn't explicitly set to ensure that evaluations always
occur in the correct path.
Add EvalContext to the GraphWalker interface.
EvalContext returns an EvalContext that has not yet set a path. This
will allow us to enforce that all context operations requiring a module
instance path will require that a path be explicitly set rather than
evaluating within the wrong path.
These are some remnants of the shadow graph functionality that was added
to support the graph builder changes in v0.8, but that has since been
removed and so there are no remaining callers for these types and
functions.
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.
Implement debugInfo and the DebugGraph
DebugInfo will be a global variable through which graph debug
information can we written to a compressed archive. The DebugInfo
methods are all safe for concurrent use, and noop with a nil receiver.
The API outside of the terraform package will be to call SetDebugInfo
to create the archive, and CloseDebugInfo() to properly close the file.
Each write to the archive will be flushed and sync'ed individually, so
in the event of a crash or a missing call to Close, the archive can
still be recovered.
The DebugGraph is a representation of a terraform Graph to be written to
the debug archive, currently in dot format. The DebugGraph also contains
an internal buffer with Printf and Write methods to add to this buffer.
The buffer will be written to an accompanying file in the debug archive
along with the graph.
This also adds a GraphNodeDebugger interface. Any node implementing
`NodeDebug() string` can output information to annotate the debug graph
node, and add the data to the log. This interface may change or be
removed to provide richer options for debugging graph nodes.
The new graph builders all delegate the build to the BasicGraphBuilder.
Having a Name field lets us differentiate the actual builder
implementation in the debug graphs.
