For child modules, a ModuleState isn't allocated until the first time a
module instance is inserted into the state under the module's path.
Normally interpolations of resource attributes are delayed until at least
one resource has been created due to the nature of the dependency graph,
but if the interpolation value is a multi-var (splat) then it is possible
that the referenced resource has count=0 and thus created _no_ resource
states when it was visited.
Previously we would crash when trying to access the resource map for the
nil module in order to count how many instances are present. Since we know
there can't be any instances present in a nil module, we now preempt
this crash by returning zero early.
This edge-case does not apply to the root module because its ModuleState
is allocated as part of initializing the main State instance.
This fixes#14438.
This was actually redundant anyway since HIL itself applied a similar
rule where any partially-unknown list would be automatically flattened
to a single unknown value.
However, now we're changing HIL to explicitly permit partially-unknown
lists so that we can allow the index operator [...] to succeed when
applied to one of the elements that _is_ known.
This, in conjunction with hashicorp/hil#51 and hashicorp/hil#52,
fixes#3449.
A couple interpolation tests were using invalid state that didn't match
the config. These will still pass but were flushed out by an attempt to
make this an error. The repl however still required interpolation
without a config, and tests there will provide a indication if this
behavior changes.
It turns out that a few use cases depend on not finding a resource
without an error.
The other code paths had sufficient nil checks for this, but there was
one place where we called Count() that needed to be checked. If the
existence of the resource matters, it would be caught at a higher level
and still return an "unknown resource" error to the user.
The change in #10787 used flatmap.Expand to fix interpolation of nested
maps, but it broke interpolation of sets such that their elements were
not represented. For example, the expected string representation of a
splatted aws_network_interface.whatever.*.private_ips should be:
```
[{Variable (TypeList): [{Variable (TypeString): 10.41.17.25}]} {Variable (TypeList): [{Variable (TypeString): 10.41.22.236}]}]
```
But instead it became:
```
[{Variable (TypeList): [{Variable (TypeString): }]} {Variable (TypeList): [{Variable (TypeString): }]}]
```
This is because the expandArray function of expand.go treated arrays to
exclusively be lists, e.g. not sets. The old code used to match for
numeric keys, so it would work for sets, whereas expandArray just
assumed keys started at 0 and ascended incrementally. Remember that
sets' keys are numeric, but since they are hashes, they can be any
integer. The result of assuming that the keys start at 0 led to the
recursive call to flatmap.Expand not matching any keys of the set, and
returning nil, which is why the above example has nothing where the IP
addresses used to be.
So we bring back that matching behavior, but we move it to expandArray
instead. We've modified it to not reconstruct the data structures like
it used to when it was in the Interpolator, and to use the standard int
sorter rather than implementing a custom sorter since a custom one is no
longer necessary thanks to the use of flatmap.Expand.
Fixes#10908, and restores the viability of the workaround I posted in #8696.
Big thanks to @jszwedko for helping me with this fix. I was able to
diagnose the problem along, but couldn't fix it without his help.
Fixes#8695
When a list count was computed in a multi-resource access
(foo.bar.*.list), we were returning the value as empty string. I don't
actually know the histocal reasoning for this but this can't be correct:
we must return unknown.
When changing this to unknown, the new tests passed and none of the old
tests failed. This leads me further to believe that the return empty
string is probably a holdover from long ago to just avoid crashes or
UUIDs in the plan output and not actually the correct behavior.
Because we now rely on HIL to do the computed calculation, we must make
sure the type is correct (TypeUnknown). Before, we'd just check for the
UUID in the string.
This changes all variable returns in the interpolater to run it through
`hil.InterfaceToVariable` which handles this lookup for us.
This makes all the computed stuff "just work" since HIL uses the same
computed sentinel value (string UUID) and the type differentiates it
from a regular string.
Fixes#5338 (and I'm sure many others)
There is no use case for "simple" variables in Terraform at all so
anytime one is found it should be an error.
There is a _huge_ backwards incompatibility here that was not supposed
to be by design but I'm sure a lot of people are relying on: in the
`template_file` datasource, this bug allowed you to not escape your
interpolations and have the work. For example:
```
data "template_file" "foo" {
template = "${a}"
vars { a = 12 }
}
```
The above would work, but it shouldn't. The template should have to be
`"$${a}"` (to escape the interpolation).
Because of this BC, I recommend holding this until Terraform 0.8.0 and
documenting it carefully. As part of this PR, I've added some special
error message notes.
Related to #5254
If the count of a resource is interpolated (i.e. `${var.c}`), then it
must be interpolated before any splat variable using that resource can
be used (i.e. `type.name.*.attr`). The original fix for #5254 is to
always ensure that this is the case.
While working on a new apply builder based on the diff in
`f-apply-builder`, this truth no longer always holds. Rather than always
include such a resource, I believe the correct behavior instead is to
use the state as a source of truth during `walkApply` operations.
This change specifically is scoped to `walkApply` operation
interpolations since we know the state of any multi-variable should be
available. The behavior is less clear for other operations so I left the
logic unchanged from prior versions.
Some of the tests for splat syntax were from the pre-list-and-map world,
and effectively flattened the values if interpolating a resource value
which was itself a list.
We now set the expected values correctly so that an interpolation like
`aws_instance.test.*.security_group_ids` now returns a list of lists.
We also fix the implementation to correctly deal with maps.
This commit makes two changes: map interpolation can now read flatmapped
structures, such as those present in remote state outputs, and lists are
sorted by the index instead of the value.
The flatmapped representation of state prior to this commit encoded maps
and lists (and therefore by extension, sets) with a key corresponding to
the number of elements, or the unknown variable indicator under a .# key
and then individual items. For example, the list ["a", "b", "c"] would
have been encoded as:
listname.# = 3
listname.0 = "a"
listname.1 = "b"
listname.2 = "c"
And the map {"key1": "value1", "key2", "value2"} would have been encoded
as:
mapname.# = 2
mapname.key1 = "value1"
mapname.key2 = "value2"
Sets use the hash code as the key - for example a set with a (fictional)
hashcode calculation may look like:
setname.# = 2
setname.12312512 = "value1"
setname.56345233 = "value2"
Prior to the work done to extend the type system, this was sufficient
since the internal representation of these was effectively the same.
However, following the separation of maps and lists into distinct
first-class types, this encoding presents a problem: given a state file,
it is impossible to tell the encoding of an empty list and an empty map
apart. This presents problems for the type checker during interpolation,
as many interpolation functions will operate on only one of these two
structures.
This commit therefore changes the representation in state of maps to use
a "%" as the key for the number of elements. Consequently the map above
will now be encoded as:
mapname.% = 2
mapname.key1 = "value1"
mapname.key2 = "value2"
This has the effect of an empty list (or set) now being encoded as:
listname.# = 0
And an empty map now being encoded as:
mapname.% = 0
Therefore we can eliminate some nasty guessing logic from the resource
variable supplier for interpolation, at the cost of having to migrate
state up front (to follow in a subsequent commit).
In order to reduce the number of potential situations in which resources
would be "forced new", we continue to accept "#" as the count key when
reading maps via helper/schema. There is no situation under which we can
allow "#" as an actual map key in any case, as it would not be
distinguishable from a list or set in state.
The mapstructure library has a regrettable backward compatibility
concern whereby a WeakDecode of []interface{}{} into a target of
map[string]interface{} yields an empty map rather than an error. One
possibility is to switch to using Decode instead of WeakDecode, but this
loses the nice handling of type conversion, requiring a large volume of
code to be added to Terraform or HIL in order to retain that behaviour.
Instead we add a DecodeHook to our usage of the mapstructure library
which checks for decoding []interface{}{} or []string{} into a map and
returns an error instead.
This has the effect of defeating the code added to retain backwards
compatibility in mapstructure, giving us the correct (for our
circumstances) behaviour of Decode for empty structures and the type
conversion of WeakDecode.
The code is identical to that in the HIL library, and packaged into a
helper.
This commit forward ports the changes made for 0.6.17, in order to store
the type and sensitive flag against outputs.
It also refactors the logic of the import for V0 to V1 state, and
fixes up the call sites of the new format for outputs in V2 state.
Finally we fix up tests which did not previously set a state version
where one is required.
Provider nodes interpolate their config during the input walk, but this
is very early and so it's pretty likely that any resources referenced are
entirely absent from the state.
As a special case then, we tolerate the normally-fatal case of having
an entirely missing resource variable so that the input walk can complete,
albeit skipping the providers that have such interpolations.
If these interpolations end up still being unresolved during refresh
(e.g. because the config references a resource that hasn't been created
yet) then we will catch that error on the refresh pass, or indeed on the
plan pass if -refresh=false is used.
This commit adds support for native list variables and outputs, building
up on the previous change to state. Interpolation functions now return
native lists in preference to StringList.
List variables are defined like this:
variable "test" {
# This can also be inferred
type = "list"
default = ["Hello", "World"]
}
output "test_out" {
value = "${var.a_list}"
}
This results in the following state:
```
...
"outputs": {
"test_out": [
"hello",
"world"
]
},
...
```
And the result of terraform output is as follows:
```
$ terraform output
test_out = [
hello
world
]
```
Using the output name, an xargs-friendly representation is output:
```
$ terraform output test_out
hello
world
```
The output command also supports indexing into the list (with
appropriate range checking and no wrapping):
```
$ terraform output test_out 1
world
```
Along with maps, list outputs from one module may be passed as variables
into another, removing the need for the `join(",", var.list_as_string)`
and `split(",", var.list_as_string)` which was previously necessary in
Terraform configuration.
This commit also updates the tests and implementations of built-in
interpolation functions to take and return native lists where
appropriate.
A backwards compatibility note: previously the concat interpolation
function was capable of concatenating either strings or lists. The
strings use case was deprectated a long time ago but still remained.
Because we cannot return `ast.TypeAny` from an interpolation function,
this use case is no longer supported for strings - `concat` is only
capable of concatenating lists. This should not be a huge issue - the
type checker picks up incorrect parameters, and the native HIL string
concatenation - or the `join` function - can be used to replicate the
missing behaviour.
This commit adds the groundwork for supporting module outputs of types
other than string. In order to do so, the state version is increased
from 1 to 2 (though the "public-facing" state version is actually as the
first state file was binary).
Tests are added to ensure that V2 (1) state is upgraded to V3 (2) state,
though no separate read path is required since the V2 JSON will
unmarshal correctly into the V3 structure.
Outputs in a ModuleState are now of type map[string]interface{}, and a
test covers round-tripping string, []string and map[string]string, which
should cover all of the types in question.
Type switches have been added where necessary to deal with the
interface{} value, but they currently default to panicking when the input
is not a string.
References to computed list-ish attributes (set, list, map) were being
improperly resolved as an empty list `[]` during the plan phase (when
the value of the reference is not yet known) instead of as an
UnknownValue.
A "diffs didn't match" failure in an AWS DirectoryServices test led to
this discovery (and this commit fixes the failing test):
https://travis-ci.org/hashicorp/terraform/jobs/104812951
Refs #2157 which has the original work to support computed list
attributes at all. This is just a simple tweak to that work.
/cc @radeksimko
This is not really improving the way we do interpolation so much as its
just shuffling bits around. I don't want to refactor interpolation in
this branch so I needed to make the current way reusable so that I can
reuse it in the new Context.
