This commit adds a new callback, DiffSuppressFunc, to the schema.Schema
structure. If set for a given schema, a callback to the user-supplied
function will be made for each attribute for which the default
type-based diff mechanism produces an attribute diff. Returning `true`
from the callback will suppress the diff (i.e. pretend there was no
diff), and returning false will retain it as part of the plan.
There are a number of motivating examples for this - one of which is
included as an example:
1. On SSH public keys, trailing whitespace does not matter in many
cases - and in some cases it is added by provider APIs. For
digitalocean_ssh_key resources we previously had a StateFunc that
trimmed the whitespace - we now have a DiffSuppressFunc which
verifies whether the trimmed strings are equivalent.
2. IAM policy equivalence for AWS. A good proportion of AWS issues
relate to IAM policies which have been "normalized" (used loosely)
by the IAM API endpoints. This can make the JSON strings differ
from those generated by iam_policy_document resources or template
files, even though the semantics are the same (for example,
reordering of `bucket-prefix/` and `bucket-prefix/*` in an S3
bucket policy. DiffSupressFunc can be used to test for semantic
equivalence rather than pure text equivalence, but without having to
deal with the complexity associated with a full "provider-land" diff
implementation without helper/schema.
Fixes issue where a resource marked as tainted with no other attribute
diffs would never show up in the plan or apply as needing to be
replaced.
One unrelated test needed updating due to a quirk in the testDiffFn
logic - it adds a "type" field diff if the diff is non-Empty. NBD
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.
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.
For a long time now, the diff logic has relied on the behavior of
`mapstructure.WeakDecode` to determine how various primitives are
converted into strings. The `schema.DiffString` function is used for
all primitive field types: TypeBool, TypeInt, TypeFloat, and TypeString.
The `mapstructure` library's string representation of booleans is "0"
and "1", which differs from `strconv.FormatBool`'s "false" and "true"
(which is used in writing out boolean fields to the state).
Because of this difference, diffs have long had the potential for
cosmetically odd but semantically neutral output like:
"true" => "1"
"false" => "0"
So long as `mapstructure.Decode` or `strconv.ParseBool` are used to
interpret these strings, there's no functional problem.
We had our first clear functional problem with #6005 and friends, where
users noticed diffs like the above showing up unexpectedly and causing
troubles when `ignore_changes` was in play.
This particular bug occurs down in Terraform core's EvalIgnoreChanges.
There, the diff is modified to account for ignored attributes, and
special logic attempts to handle properly the situation where the
ignored attribute was going to trigger a resource replacement. That
logic relies on the string representations of the Old and New fields in
the diff to be the same so that it filters properly.
So therefore, we now get a bug when a diff includes `Old: "0", New:
"false"` since the strings do not match, and `ignore_changes` is not
properly handled.
Here, we introduce `TypeBool`-specific normalizing into `finalizeDiff`.
I spiked out a full `diffBool` function, but figuring out which pieces
of `diffString` to duplicate there got hairy. This seemed like a simpler
and more direct solution.
Fixes#6005 (and potentially others!)
* MaxItems defines a maximum amount of items that can exist within a
TypeSet or TypeList. Specific use cases would be if a TypeSet is being
used to wrap a complex structure, however more than one instance would
cause instability.
I promised myself that next time I jumped in this file I'd fix this up.
Now we don't have to manually index the file with comments, we can just
add descriptive names to the test cases!
Previous this would return the following sort of error:
expected type 'string', got unconvertible type '[]interface {}'
This is the raw error returned by the underlying mapstructure library.
This is not a helpful error message for anyone who doesn't know Go's
type system, and it exposes Terraform's internals to the UI.
Instead we'll catch these cases before we try to use mapstructure and
return a more straightforward message.
By checking the type before the IsComputed exception this also avoids
a crash caused when the assigned value is a computed list. Otherwise
the list of interpolations is allowed through here and then crashes later
during Diff when the value is not a primitive as expected.
A common issue with new resource implementations is not considering parts
of a complex structure that's used inside a set, which causes quirky
behavior.
The schema helper has enough information to provide a default reasonable
implementation of a set function that includes all non-computed attributes
in a deterministic way. Here we implement such a function and use it
when no explicit hashing function is provided.
In order to achieve this we encapsulate the construction of the zero
value for a schema in a new method schema.ZeroValue, which allows us to
put the fallback logic to the new default function in a single spot.
It is no longer valid to use &Set{F: schema.Set} and all uses of that
construct should be replaced with schema.ZeroValue().(*Set) .
In `helper/schema` we already makes a distinction between `Default`
which is always applied and `InputDefault` which is displayed to the
user for an empty field.
But for variables we just have `Default` which is treated like
`InputDefault`. This changes it to _not_ prompt the user for a value
when the variable declaration includes a default.
Treating this as a UX bugfix and the "don't prompt for variables w/
defaults set" behavior as the originally expected behavior we were
failing to honor.
Added an already-passing test to verify and cover the `helper/schema`
behavior.
Perhaps down the road we can add a `input_default` attribute to
variables to allow similar behavior to `helper/schema` in variables, but
for now just sticking with the fix.
Fixes#2592
This is the initial pure "all tests passing without a diff" stage. The
plan is to change the internal representation of StringList to include a
suffix delimiter, which will allow us to recognize empty and
single-element lists.
I couldn't see a simple path get this working for Maps, Sets,
and Lists, so lets land it as a primitive-only schema feature.
I think validation on primitives comprises 80% of the use cases anyways.
Guarantees that the `interface{}` arg to ValidateFunc is the proper
type, allowing implementations to be simpler.
Finish the docstring on `ValidateFunc` to call this out.
/cc @mitchellh
Removed fields show a customizable error message to the user when they
are used in a Terraform config. This is a tool that provider authors can
use for user feedback as they evolve their Schemas.
refs #957
Deprecated fields show a customizable warning message to the user when
they are used in a Terraform config. This is a tool that provider
authors can use for user feedback as they evolve their Schemas.
fixes#957
James Nugent