This was accidentally missed on the first pass of module call decoding.
As before, this is a map from child provider config address to parent
provider config address, allowing the set of providers to be projected in
arbitrary ways into a child module.
Previously we just ported over the simple "string", "list", and "map" type
hint keywords from the old loader, which exist primarily as hints to the
CLI for whether to treat -var=... arguments and environment variables as
literal strings or as HCL expressions.
However, we've been requested before to allow more specific constraints
here because it's generally better UX for a type error to be detected
within an expression in a calling "module" block rather than at some point
deep inside a third-party module.
To allow for more specific constraints, here we use the type constraint
expression syntax defined as an extension within HCL, which uses the
variable and function call syntaxes to represent types rather than values,
like this:
- string
- number
- bool
- list(string)
- list(any)
- list(map(string))
- object({id=string,name=string})
In native HCL syntax this looks like:
variable "foo" {
type = map(string)
}
In JSON, this looks like:
{
"variable": {
"foo": {
"type": "map(string)"
}
}
}
The selection of literal processing or HCL parsing of CLI-set values is
now explicit in the model and separate from the type, though it's still
derived from the type constraint and thus not directly controllable in
configuration.
Since this syntax is more complex than the keywords that replaced it, for
now the simpler keywords are still supported and "list" and "map" are
interpreted as list(any) and map(any) respectively, mimicking how they
were interpreted by Terraform 0.11 and earlier. For the time being our
documentation should continue to recommend these shorthand versions until
we gain more experience with the more-specific type constraints; most
users should just make use of the additional primitive type constraints
this enables: bool and number.
As a result of these more-complete type constraints, we can now type-check
the default value at config load time, which has the nice side-effect of
allowing us to produce a tailored error message if an override file
produces an invalid situation; previously the result was rather confusing
because the error message referred to the original definition of the
variable and not the overridden parts.
The initial pass of implementation here missed the special case where
ignore_changes can, in the old parser, be set to ["*"] to ignore changes
to all attributes.
Since that syntax is awkward and non-obvious, our new decoder will instead
expect ignore_changes = all, using HCL2's capability to interpret an
expression as a literal keyword. For compatibility with old configurations
we will still accept the ["*"] form but emit a deprecation warning to
encourage moving to the new form.
In our new loader we are changing certain values in configuration to be
naked keywords or references rather than quoted strings as before. Since
many of these have been shown in books, tutorials, and our own
documentation we will make the old forms generate deprecation warnings
rather than errors so that newcomers starting from older documentation
can be eased into the new syntax, rather than getting blocked.
This will also avoid creating a hard compatibility wall for reusable
modules that are already published, allowing them to still be used in
spite of these warnings and then fixed when the maintainer is able.
BuildConfig creates a module tree by recursively walking through module
calls in the root module and any descendent modules. This is intended to
be used both for the simple case of loading already-installed modules and
the more complex case of installing modules inside "terraform init", both
of which will be dealt with in a separate package.
mergeBody is a hcl.Body implementation that deals with our override file
merging behavior for the portions of the configuration that are not
processed until full eval time.
Mimicking the behavior of our old config merge implementation from the
"config" package, the rules here are:
- Attributes in the override body hide attributes of the same name in
the base body.
- Any block in the override body hides all blocks with the same type name
that appear in the base body.
This is tested by a new test for the overriding of module arguments, which
asserts the correct behavior of the merged body as part of its work.
Some of the fields in our config structs are either mandatory in primary
files or there is a default value that we apply if absent.
Unfortunately override files impose the additional constraint that we
be allowed to omit required fields (which have presumably already been
set in the primary files) and that we are able to distinguish between a
default value and omitting a value entirely.
Since most of our fields were already acceptable for override files, here
we just add some new fields to deal with the few cases where special
handling is required and a helper function to disable the "Required" flag
on attributes in a given schema.
This method wraps LoadConfigFile to load all of the .tf and .tf.json files
in a given directory and then bundle them together into a Module object.
This function also deals with the distinction between primary and override
files, first appending together the primary files in lexicographic order
by filename, and then merging in override files in the same order.
The merging behavior is not fully implemented as of this commit, and so
will be expanded in future commits.
Much like TestParserLoadConfigFileSuccess, this is intended to be an
easy-to-maintain collection of bad examples to test different permutations
of our error handling.
As with TestParserLoadConfigFileSuccess, we should also have more specific
tests alongside this that check that the error outcome is what was
expected, since this test just accepts any error and may thus not be
testing what we think it is.
This test is intended to be an easy-to-maintain catalog of good examples
that we can use to catch certain parsing or decoding regressions easily.
It's not a fully-comprehensive test since it doesn't check the result
of decoding, instead just accepting any decode that completes without
errors. However, an easy-to-maintain test like this is a good complement
to some more specialized tests since we can easily collect good examples
over time and just add them in here.
Martin Atkins