This is the frontend to the work-in-progress codepath for upgrading the
source code for a module written for Terraform v0.11 or earlier to use
the new syntax and idiom of v0.12.
The underlying upgrade code is not yet complete as of this commit, and
so the command is not yet very useful. We will continue to iterate on
the upgrade code in subsequent commits.
This covers all of the expression node types in HIL's AST, and also
includes initial support for some of our top-level blocks so that we can
easily test that.
The initial implementations of the "variable" and "output" blocks are
pretty redundant and messy, so we can hopefully improve on these in a
later pass.
This function is the main functionality of this package. So far it just
deals with detecting and renaming JSON files that are mislabeled as
native syntax files. Other functionality will follow in later commits.
This package will do all of its work in-memory so that it can avoid making
partial updates and then failing, so we need to be able to load the
sources files from a particular directory into memory.
The upgrade process isn't idempotent, so we also attempt to detect
heuristically whether an upgrade has already been performed (can parse
with the new parser and has a version constraint that prevents versions
earlier than 0.12) so that the CLI tool that will eventually wrap this
will be able to produce a warning and prompt for confirmation in that
case.
Although the new HCL implementation and configuration loader is broadly
compatible with the prior implementation, it has a number of new idiomatic
forms and it also cannot parse some more extreme non-idiomatic usages
that were possible under the old parser.
To help users migrate to the new implementation, this package will rewrite
configuration to comply with the new idiom and fix as many cases as
possible where the legacy parser was too liberal or exposed implementation
details.
Martin Atkins