In early versions of Terraform where the interpolation language didn't
have any real list support, list brackets around a single string was the
signal to split the string on a special uuid separator to produce a list
just in time for processing, giving expressions like this:
foo = ["${test_instance.foo.*.id}"]
Logically this is weird because it looks like it should produce a list
of lists of strings. When we added real list support in Terraform 0.7 we
retained support for this behavior by trimming off extra levels of list
during evaluation, and inadvertently continued relying on this notation
for correct type checking.
During the Terraform 0.10 line we fixed the type checker bugs (a few
remaining issues notwithstanding) so that it was finally possible to
use the more intuitive form:
foo = "${test_instance.foo.*.id}"
...but we continued trimming off extra levels of list for backward
compatibility.
Terraform 0.12 finally removes that compatibility shim, causing redundant
list brackets to be interpreted as a list of lists.
This upgrade rule attempts to identify situations that are relying on the
old compatibility behavior and trim off the redundant extra brackets. It's
not possible to do this fully-generally using only static analysis, but
we can gather enough information through or partial type inference
mechanism here to deal with the most common situations automatically and
produce a TF-UPGRADE-TODO comment for more complex scenarios where the
user intent isn't decidable with only static analysis.
In particular, this handles by far the most common situation of wrapping
list brackets around a splat expression like the first example above.
After this and the other upgrade rules are applied, the first example
above will become:
foo = test_instance.foo.*.id
By collecting information about the input variables during analysis, we
can return approximate type information for any references to those
variables in expressions.
Since Terraform 0.11 allowed maps of maps and lists of lists in certain
circumstances even though this was documented as forbidden, we
conservatively return collection types whose element types are unknown
here, which allows us to do shallow inference on them but will cause
us to get an incomplete result if any operations are performed on
elements of the list or map value.
Although we can't do fully-precise type inference with access only to a
single module's configuration, we can do some approximate inference using
some clues within the module along with our resource type schemas.
This depends on HCL's ability to pass through type information even if the
input values are unknown, mapping our partial input type information into
partial output type information by evaluating the same expressions.
This will allow us to do some upgrades that require dynamic analysis to
fully decide, by giving us three outcomes: needed, not needed, or unknown.
If it's unknown then that'll be our prompt to emit a warning for the user
to make a decision.
This is a temporary implementation of these rules just so that these can
be passed through verbatim (rather than generating an error) while we
do testing of other features.
A subsequent commit will finish these with their own custom rulesets.
The main tricky thing here is ignore_changes, which contains strings that
are better given as naked traversals in 0.12. We also handle here mapping
the old special case ["*"] value to the new "all" keyword.
Both resource blocks and module blocks contain references to providers
that are expressed as short-form provider addresses ("aws.foo" rather than
"provider.aws.foo").
These rules call for those to be unwrapped as naked identifiers during
upgrade, rather than appearing as quoted strings. This also introduces
some further rules for other simpler meta-arguments that are required
for the test fixtures for this feature.
Some further rules are required here to deal with the meta-arguments we
accept inside these blocks, but this is good enough to pass through most
module blocks using the standard attribute-expression-based mapping.
Previously we were handling this one as a special case, effectively
duplicating most of the logic from upgradeBlockBody.
By doing some prior analysis of the block we can produce a "rules" that
just passes through all of the attributes as-is, allowing us to reuse
upgradeBlockBody. This is a little weird for the locals block since
everything in it is user-selected names, but this facility will also be
useful in a future commit for dealing with module blocks, which contain
a mixture of user-chosen and reserved argument names.
We don't change JSON files at all and instead just emit a warning about
them since JSON files are usually generated rather than hand-written and
so any updates need to happen in the generator program rather than in its
output.
However, we do still need to copy them verbatim into the output map so
that we can keep track of them through any subsequent steps.
Prior to v0.12 Terraform was liberal about these and allowed them to
mismatch, but now it's important to get this right so that resources
and resource instances can be used directly as object values, and so
we'll fix up any sloppy existing references so things keep working as
expected.
This is particularly important for the pattern of using count to create
conditional resources, since previously the "true" case would create one
instance and Terraform would accept an unindexed reference to that.
The reference syntax is not significantly changed, but there are some
minor additional restrictions on identifiers in HCL2 and as a special case
we need to rewrite references to data.terraform_remote_state .
Along with those mandatory upgrades, we will also switch references to
using normal index syntax where it's safe to do so, as part of
de-emphasizing the old strange integer attribute syntax (like foo.0.bar).
Previously we were erroneously moving these out of their original block
into the surrounding body. Now we'll make sure to collect up any remaining
ad-hoc comments inside a nested block body before closing it.
Early on it looked like we wouldn't need to distinguish these since we
were only analyzing for provider types, but we're now leaning directly
on the resource addresses later on and so we need to make sure we produce
valid ones when data resources are present.
Users discovered that they could exploit some missing validation in
Terraform v0.11 and prior to treat block types as if they were attributes
and assign dynamic expressions to them, with some significant caveats and
gotchas resulting from the fact that this was never intended to work.
However, since such patterns are in use in the wild we'll convert them
to a dynamic block during upgrade. With only static analysis we must
unfortunately generate a very conservative, ugly dynamic block with
every possible argument set. Users ought to then clean up the generated
configuration after confirming which arguments are actually required.
We're using break elsewhere in here so it was weird to have a small set
of situations that return instead, which could then cause confusion for
future maintenance if a reader doesn't notice that control doesn't always
leave the outer switch statement.
If lookup is being used with only two arguments then it is equivalent to
index syntax and more readable that way, so we'll replace it.
Ideally we'd do similarly for element(...) here but sadly we cannot
because we can't prove in static analysis that the user is not relying
on the modulo wraparound behavior of that function.
We now have native language features for declaring tuples and objects,
which are the idiomatic way to construct sequence and mapping values that
can then be converted to list, set, and map types as needed.
In the old world, lists and maps could be created either using functions
in HIL or list/object constructs in HCL. Here we ensure that in the HCL
case we'll apply any required expression transformations to the individual
items within HCL's compound constructs.
Previously we were using the line count difference between the start of
one item and the next to decide whether to insert a blank line between
two items, but that is incorrect for multi-line items.
Instead, we'll now count the difference from the final line of the
previous item to the first line of the next, as best we can with the
limited position info recorded by the HCL1 parser.
The old parser was forgiving in allowing the use of block syntax where a
map attribute was expected, but the new parser is not (in order to allow
for dynamic map keys, for expressions, etc) and so the upgrade tool must
fix these to use attribute syntax.
The main area of interest in upgrading is dealing with special cases for
individual block items, so this generalization allows us to use the same
overall body-processing logic for everything but to specialize just how
individual items are dealt with, which we match by their names as given
in the original input source code.
This involved some refactoring of how block bodies are migrated, which
still needs some additional work to deal with meta-arguments but is now
at least partially generalized to support both resource and provider
blocks.
This allows basic static validation of a traversal against a schema, to
verify that it represents a valid path through the structural parts of
the schema.
The main purpose of this is to produce better error messages (using our
knowledge of the schema) than we'd be able to achieve by just relying
on HCL expression evaluation errors. This is particularly important for
nested blocks because it may not be obvious whether one is represented
internally by a set or a list, and incorrect usage would otherwise produce
a confusing HCL-oriented error message.
We want the forthcoming v0.12.0 release to be the last significant
breaking change to our main configuration constructs for a long time, but
not everything could be implemented in that release.
As a compromise then, we reserve various names we have some intent of
using in a future release so that such future uses will not be a further
breaking change later.
Some of these names are associated with specific short-term plans, while
others are reserved conservatively for possible later work and may be
"un-reserved" in a later release if we don't end up using them. The ones
that we expect to use in the near future were already being handled, so
we'll continue to decode them at the config layer but also produce an
error so that we don't get weird behavior downstream where the
corresponding features don't work yet.
Since our new approach here works by installing with a synthetic module
configuration block, we need to treat relative paths as a special case
for two reasons:
- Relative paths in module addresses are relative to the file containing
the call rather than the working directory, but -from-module uses the
working directory (and the call is in a synthetic "file" anyway)
- We need to force Terraform to pass the path through to go-getter rather
than just treating it as a relative reference, since we really do want
a copy of the directory in this case, even if it is local.
To address both of these things, we'll detect a relative path and turn it
into an absolute path before beginning installation. This is a bit hacky,
but this is consistent with the general philosophy of the -from-module
implementation where it does hacky things so that the rest of the
installer code can be spared of dealing with its special cases.
This is covered by a couple of existing tests that run init -from-module,
including TestInit_fromModule_dstInSrc which now passes.
The tests in here are illustrating that this package is not yet finished,
but we plan to run a release before we finish this and so we'll skip those
tests for now with the intent of reinstating this again once we return
to finish this up.
The test provider comes with a lot of baggage since it's designed to be
used as a plugin, so instead we'll just use the mock provider
implementation directly, and so we can (in a later commit) configure it
appropriately for what our tests need here.
This is still not compileable because the test provider needs to be
updated to the new provider interface, but all the rest of the types are
now correct so we can update the test provider in a later commit to make
this work again.
Given a module foo and a module foo/bar, the previous code might
incorrectly treat "bar" as a file within "foo" rather than as a module
directory in its own right.
We need to make the collection itself be a tuple or object rather than
list or map in this case, since otherwise all of the elements of the
collection are constrained to be of the same type and that isn't the
intent of a provider indicating that it accepts any type.
This produces a "proposed new state", which already has prior computed
values propagated into it (since that behavior is standard for all
resource types) but could be customized further by the provider to make
the "_planned_ new state".
In the process of implementing this it became clear that our configschema
DecoderSpec behavior is incorrect, since it's producing list values for
NestingList and map values for NestingMap. While that seems like it should
be right, we should actually be using tuple and object types respectively
to allow each block to have a different runtime type in situations where
an attribute is given the type cty.DynamicPseudoType. That's not fixed
here, and so without a further fix list and map blocks will panic here.
The DecoderSpec implementation will be fixed in a subsequent commit.
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.
Any value that is not set in the configuration should decode as a Null
value. Unknown should still be returned if a computed value expression
is unknown.
The "config" package is no longer used and will be removed as part
of the 0.12 release cleanup. Since configschema is part of the
"new world" of configuration modelling, it makes more sense for
it to live as a subdirectory of the newer "configs" package.
In order to properly migrate the contents of resource, data, provider and
provisioner blocks we will need the provider's schema in order to
understand what is expected, so we can resolve some ambiguities inherent
in the legacy HCL AST.
This includes an initial prototype of migrating the content of resource
blocks just to verify that the information is being gathered correctly.
As with the rest of the upgrade_native.go file, this will be reorganized
significantly once the basic end-to-end flow is established and we can
see how to organize this code better.
