This is a requirement for the parallelism of Terraform to work sanely.
We could deep copy every result but I think this would be unrealistic
and impose a performance cost when it isn't necessary in most cases.
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.
The Deposed slice wasn't being normalized and nil values could be read
in from a state file. Filter out the nils during init. There is
still a bug in copystructure, but that will be addressed separately.
A nil InstanceState within State/Modules/Resources/Deposed will panic
during a deep copy. The panic needs to be fixed in copystructure, but
the nil probably should have been normalized out before we got here too.
There were races with ValidateResource in the provider initializing the
data which resulting in lost data for the shadow. A new "Init" function
has been added to the shadow structs to support safe concurrent
initialization.
This adds a new function to get a unique identifier scoped to the graph
walk in order to identify operations against the same instance. This is
used by the shadow to namespace provider function calls.
We allow the built in context to work as expected and shadow just the
components now. This is better since it allows us to use much more of
the REAL structures.
The arguments passed into Apply, Refresh, Diff could be modified which
caused the shadow comparison later to cause errors. Also, the result
should be deep copied so that it isn't modified.
This is necessary so that the shadow version can actually keep track of
what provider is used for what. Before, providers for different alises
were just initialized but the factory had no idea. Arguably this is fine
but when trying to build a shadow graph this presents challenges.
With these changes, we now pass an opaque "uid" through that is used to
keep track of the providers and what real maps to what shadow.
This fixes an issue where orphaned grandchild modules don't properly
inherit their provider configurations from grandparents. I found this
while working on shadow graphs (the shadow graph actually caught an
inconsistency between runs and exposed this bug!), so I'm unsure if this
affects any issue.
To better explain the issue, I'll diagram things.
Here is a hierarchy that _works_ (w/o this PR):
```
root
|-- child1 (orphan)
|-- child2
|-- grandchild
```
All modules in this case will successfully inherit provider
configurations from "root".
Here is a hierarchy that _doesn't work without this PR_:
```
root
|-- child1 (orphan)
|-- grandchild (orphan)
```
In this case, `child1` does successfully inherit the provider from root,
but `grandchild` _will not_ unless `child1` had resources. If `child1`
has no resources, it wouldn't inherit anything. This PR fixes that.
A map value read from a config file will be the default
`[]map[string]interface{}` type decoded from HCL. Since this type can't
be applied to a variable, it's likely that it was a simple map. If
there's a single map value, we can pull that out of the slice during
Eval.
This commit improves the error logging for "Diffs do not match" errors
by using the go-spew library to ensure that the structures are presented
fully and in a consistent order. This allows use of the command line
diff tool to analyse what is wrong.
This implements DeepCopy, still need to implement Equals to make this
more useful. Coming in the next commit but this still has its own full
functionality + tests.
A JSON object will be decoded as a list with a single map value. This
will be properly coerced later, so let it through the initial config
semantic checks.
A race when accessing Provisioner.RawConfig can cause unexpected output
for provisioners that interpolate variables. Use RawConfig.Copy which
needs to acquire the RawConfig mutex to get the values.
Fixes#8890
In an attempt to always show "id" as computed we were producing a
synthetic diff for it, but this causes problems when the id attribute for
a particular data source is actually settable in configuration, since it
masks the setting from the config and forces it to always be empty.
Instead, we'll set it conditionally so that a value provided in the config
can shine through when available.
We con no longer copy an InstanceState via a simple
dereference+assignment because of the mutex which can't be copied. This
adds a set method to properly set all field from another InstanceState,
and take the appropriate locks while doing so.
Add locks to the state structs to handle concurrency during the graph
walks. We can't embed the mutexes due to serialization constraints when
communicating with providers, so expose the Lock/Unlock methods
manually.
Use copystructure.LockedCopy to ensure locks are honored.
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
Fix checksum issue with remote state
If we read a state file with "null" objects in a module and they become
initialized to an empty map the state file may be written out with empty
objects rather than "null", changing the checksum. If we can detect
this, increment the serial number to prevent a conflict in atlas.
Our fakeAtlas test server now needs to decode the state directly rather
than using the ReadState function, so as to be able to read the state
unaltered.
The terraform.State data structures have initialization spread out
throughout the package. More thoroughly initialize State during
ReadState, and add a call to init() during WriteState as another
normalization safeguard.
Expose State.init through an exported Init() method, so that a new State
can be completely realized outside of the terraform package.
Additionally, the internal init now completely walks all internal state
structures ensuring that all maps and slices are initialized. While it
was mentioned before that the `init()` methods are problematic with too
many call sites, expanding this out better exposes the entry points that
will need to be refactored later for improved concurrency handling.
The State structures had a mix of `omitempty` fields. Remove omitempty
for all maps and slices as part of this normalization process. Make
Lineage mandatory, which is now explicitly set in some tests.
Set the default log package output to iotuil.Discard during tests if the
`-v` flag isn't set. If we are verbose, then apply the filter according
to the TF_LOG env variable.
When targeting, only Addressable untargeted nodes were being removed
from the graph. Variable nodes are not directly Addressable, so they
were hanging around. This caused problems with module variables that
referred to Resource nodes. The Resource node would be filtered out of
the graph, but the module Variable node would not, so it would try to
interpolate during the graph walk and be unable to find it's referent.
This would present itself as strange "cannot find variable" errors for
variables that were uninvolved with the currently targeted set of
resources.
Here, we introduce a new interface that can be implemented by graph
nodes to indicate they should be filtered out from targeting even though
they are not directly addressable themselves.
The behaviour whereby outputs for a particular nested module can be
output was broken by the changes for lists and maps. This commit
restores the previous behaviour by passing the module path into the
outputsAsString function.
We also add a new test of this since the code path for indivdual output
vs all outputs for a module has diverged.
This PR fixes#7824, which crashed when applying a plan file. The bug is
that while a map which has come from the HCL parser reifies as a
[]map[string]interface{}, the variable saved in the plan file was not.
We now cover both cases.
Fixes#7824.
Terraform 0.7 introduces lists and maps as first-class values for
variables, in addition to string values which were previously available.
However, there was previously no way to override the default value of a
list or map, and the functionality for overriding specific map keys was
broken.
Using the environment variable method for setting variable values, there
was previously no way to give a variable a value of a list or map. These
now support HCL for individual values - specifying:
TF_VAR_test='["Hello", "World"]'
will set the variable `test` to a two-element list containing "Hello"
and "World". Specifying
TF_VAR_test_map='{"Hello = "World", "Foo" = "bar"}'
will set the variable `test_map` to a two-element map with keys "Hello"
and "Foo", and values "World" and "bar" respectively.
The same logic is applied to `-var` flags, and the file parsed by
`-var-files` ("autoVariables").
Note that care must be taken to not run into shell expansion for `-var-`
flags and environment variables.
We also merge map keys where appropriate. The override syntax has
changed (to be noted in CHANGELOG as a breaking change), so several
tests needed their syntax updating from the old `amis.us-east-1 =
"newValue"` style to `amis = "{ "us-east-1" = "newValue"}"` style as
defined in TF-002.
In order to continue supporting the `-var "foo=bar"` type of variable
flag (which is not valid HCL), a special case error is checked after HCL
parsing fails, and the old code path runs instead.
We conditionally format version with VersionPrerelease in a number of
places. Add a package-level function where we can unify the version
format. Replace most of version formatting in terraform, but leave th
few instances set from the top-level package to make sure we don't break
anything before release.
This adds some unit tests for config maps with dots in the key values.
We check for maps with keys which have overlapping names. There are
however still issues with nested maps which create overlapping flattened
names, as well as nested lists with dots in the key.
This is the first step in allowing overrides of map and list variables.
We convert Context.variables to map[string]interface{} from
map[string]string and fix up all the call sites.
The report in #7378 led us into a deep rabbit hole that turned out to
expose a bug in the graph walk implementation being used by the
`NoopTransformer`. The problem ended up being when two nodes in a single
dependency chain both reported `Noop() -> true` and needed to be
removed. This was breaking the walk and preventing the second node from
ever being visited.
Fixes#7378
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 set of changes addresses two bug scenarios:
(1) When an ignored change canceled a resource replacement, any
downstream resources referencing computer attributes on that resource
would get "diffs didn't match" errors. This happened because the
`EvalDiff` implementation was calling `state.MergeDiff(diff)` on the
unfiltered diff. Generally this is what you want, so that downstream
references catch the "incoming" values. When there's a potential for the
diff to change, thought, this results in problems w/ references.
Here we solve this by doing away with the separate `EvalNode` for
`ignore_changes` processing and integrating it into `EvalDiff`. This
allows us to only call `MergeDiff` with the final, filtered diff.
(2) When a resource had an ignored change but was still being replaced
anyways, the diff was being improperly filtered. This would cause
problems during apply when not all attributes were available to perform
the replacement.
We solve that by deferring actual attribute removal until after we've
decided that we do not have to replace the resource.
As part of evaluating a variable block, there is a pass made on unknown
keys setting them to the config.DefaultVariableValue sentinal value.
Previously this only took into account one level of nesting and assumed
all values were strings.
This commit now traverses the unknown keys via lists and maps and sets
unknown map keys surgically.
Fixes#7241.
The reproduction of issue #7421 involves a list of maps being passed to
a module, where one or more of the maps has a value which is computed
(for example, from another resource). There is a failure at the point of
use (via lookup interpolation) of the computed value of the form:
```
lookup: lookup failed to find 'elb' in:
${lookup(var.services[count.index], "elb")}
```
Where 'elb' is the key of the map.
* Fix nested module "unknown variable" during dstry
During a destroy with nested modules, accessing a variable between them
causes an "unknown variable accessed" during destroy.
Passing a literal map to a module looks like this in HCL:
module "foo" {
source = "./foo"
somemap {
somekey = "somevalue"
}
}
The HCL parser always wraps an extra list around the map, so we need to
remove that extra list wrapper when the parameter is indeed of type "map".
Fixes#7140
In scenarios with a lot of small configs, it's tedious to fan out actual
dir trees in a test-fixtures dir. It also spreads out the context of the
test - requiring the reader fetch a bunch of scattered 3 line files in
order to understand what is being tested.
Our config loading code still only reads from disk, but in
the `helper/resource` acc test framework we work around this by writing
inline config to temp files and loading it from there. This helper is
based on that strategy.
Eventually it'd be great to be able to build up a `module.Tree` from
config directly, but this gets us the functionality today.
Example Usage:
testModuleInline(t, map[string]string{
"top.tf": `
module "middle" {
source = "./middle"
}
`,
"middle/mid.tf": `
module "bottom" {
source = "./bottom"
amap {
foo = "bar"
}
}
`,
"middle/bottom/bot.tf": `
variable "amap" {
type = "map"
}
`,
}),
In #7170 we found two scenarios where the type checking done during the
`context.Validate()` graph walk was circumvented, and the subsequent
assumption of type safety in the provider's `Diff()` implementation
caused panics.
Both scenarios have to do with interpolations that reference Computed
values. The sentinel we use to indicate that a value is Computed does
not carry any type information with it yet.
That means that an incorrect reference to a list or a map in a string
attribute can "sneak through" validation only to crop up...
1. ...during Plan for Data Source References
2. ...during Apply for Resource references
In order to address this, we:
* add high-level tests for each of these two scenarios in `provider/test`
* add context-level tests for the same two scenarios in `terraform`
(these tests proved _really_ tricky to write!)
* place an `EvalValidateResource` just before `EvalDiff` and `EvalApply` to
catch these errors
* add some plumbing to `Plan()` and `Apply()` to return validation
errors, which were previously only generated during `Validate()`
* wrap unit-tests around `EvalValidateResource`
* add an `IgnoreWarnings` option to `EvalValidateResource` to prevent
active warnings from halting execution on the second-pass validation
Eventually, we might be able to attach type information to Computed
values, which would allow for these errors to be caught earlier. For
now, this solution keeps us safe from panics and raises the proper
errors to the user.
Fixes#7170
The Outputs and Resources maps in the state modules are expected to be
non-nil, and initialized that way when a new module is added to the
state. The V1->V2 upgrade was setting the maps to nil if the len == 0.
Always increment the state serial whenever we upgrade the state version.
This prevents possible version conflicts between local and remote state
when one has been upgraded, but the serial numbers match.
Just like computed sets, computed maps may have both different values
and different cardinality after they're computed. Remove the computed
maps and the values from the compared diffs.
This commit test "TestContext2Input_moduleComputedOutputElement"
by ensuring that we treat a count of zero and non-reified resources
independently rather than returning an empty list for both, which
results in an interpolation failure when using the element function or
indexing.
This test illustrates a failure which occurs during the Input walk, if
an interpolation is used with the input of a splat operation resulting
in a multi-variable.
The bug was found during use of the RC2, but does not correspond to an
open issue at present.
The implementation of Stringer on OutputState previously assumed outputs
may only be strings - we now no longer cast to string, instead using the
built in formatting directives.
The previous mechanism for testing state threw away the mutation made on
the state by calling State() twice - this commit corrects the test to
match the comment.
In addition, we replace the custom copying logic with the copystructure
library to simplify the code.
In cases where we construct state directly rather than reading it via
the usual methods, we need to ensure that the necessary maps are
initialized correctly.
When checking for "same" values in a computed hash, not only might some
of the values differ between versions changing the hash, but there may be
fields not included at all in the original map, and different overall
counts.
Instead of trying to match individual set fields with different hashes,
remove any hashed key longer than the computed key with the same base
name.
Previously, interpolation of multi-variables was returning an empty
variable if the resource count was 0. The empty variable was defined as
TypeString, Value "". This means that empty resource counts fail type
checking for interpolation functions which operate on lists.
Instead, return an empty list if the count is 0. A context test tests
this against further regression. Also add a regression test covering the
case of a single count multi-variable.
In order to make the context testing framework deal with this change it
was necessary to special case empty lists in the test diff function.
Fixes#7002
For `terraform destroy`, we currently build up the same graph we do for
`plan` and `apply` and we do a walk with a special Diff that says
"destroy everything".
We have fought the interpolation subsystem time and again through this
code path. Beginning in #2775 we gained a new feature to selectively
prune out problematic graph nodes. The past chain of destroy fixes I
have been involved with (#6557, #6599, #6753) have attempted to massage
the "noop" definitions to properly handle the edge cases reported.
"Variable is depended on by provider config" is another edge case we add
here and try to fix.
This dive only makes me more convinced that the whole `terraform
destroy` code path needs to be reworked.
For now, I went with a "surgical strike" approach to the problem
expressed in #7047. I found a couple of issues with the existing
Noop and DestroyEdgeInclude logic, especially with regards to
flattening, but I'm explicitly ignoring these for now so we can get this
particular bug fixed ahead of the 0.7 release. My hope is that we can
circle around with a fully specced initiative to refactor `terraform
destroy`'s graph to be more state-derived than config-derived.
Until then, this fixes#7407
The work integrated in hashicorp/terraform#6322 silently broke the
ability to use remote state correctly. This commit adds a fix for that,
making use of the work integrated in hashicorp/terraform#7124.
In order to deal with outputs which are complex structures, we use a
forked version of the flatmap package - the difference in the version
this commit vs the github.com/hashicorp/terraform/flatmap package is
that we add in an additional key for map counts which state requires.
Because we bypass the normal helper/schema mechanism, this is not set
for us.
Because of the HIL type checking of maps, values must be of a homogenous
type. This is unfortunate, as it means we can no longer refer to outputs
as:
${terraform_remote_state.foo.output.outputname}
Instead we had to bring them to the top level namespace:
${terraform_remote_state.foo.outputname}
This actually does lead to better overall usability - and the BC
breakage is made better by the fact that indexing would have broken the
original syntax anyway.
We also add a real-world test and assert against specific values. Tests
which were previously acceptance tests are now run as unit tests, so
regression should be identified at a much earlier stage.
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 lineage of a state is an identifier shared by a set of states whose
serials are meaningfully comparable because they are produced by
progressive Refresh/Apply operations from the same initial empty state.
This is initialized as a type-4 (random) UUID when a new state is
initialized and then preserved on all other changes.
Since states before this change will not have lineage but users may wish
to set a lineage for an existing state in order to get the safety
benefits it will grow to imply, an empty lineage is considered to be
compatible with all lineages.
This commit makes the current Terraform state version 3 (previously 2),
and a migration process as part of reading v2 state. For the most part
this is unnecessary: helper/schema will deal with upgrading state for
providers written with that framework. However, for providers which
implemented the resource model directly, this gives a best-efforts
attempt at lossless upgrade.
The heuristics used to change the count of a map from the .# key to the
.% key are as follows:
- if the flat map contains any non-numeric keys, we treat it as a
map
- if the map is empty it must be computed or optional, so we remove
it from state
There is a known edge condition: maps with all-numeric keys are
indistinguishable from sets without access to the schema. They will need
manual conversion or may result in spurious diffs.
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 removes support for the V0 binary state format which was present in
Terraform prior to 0.3. We still check for the file type and present an
error message explaining to the user that they can upgrade it using a
prior version of Terraform.
This an effort to address hashicorp/terraform#516.
Adding the Sensitive attribute to the resource schema, opening up the
ability for resource maintainers to mark some fields as sensitive.
Sensitive fields are hidden in the output, and, possibly in the future,
could be encrypted.
During accpeptance tests of some of the first data sources (see
hashicorp/terraform#6881 and hashicorp/terraform#6911),
"unknown resource type" errors have been coming up. Traced it down to
the ResourceCountTransformer, which transforms destroy nodes to a
graphNodeExpandedResourceDestroy node. This node's EvalTree() was still
indiscriminately using EvalApply for all resource types, versus
EvalReadDataApply. This accounts for both cases via EvalIf.
Previously the plan phase would produce a data diff only if no state was
already present. However, this is a faulty approach because a state will
already be present in the case where the data resource depends on a
managed resource that existed in state during refresh but became
computed during plan, due to a "forces new resource" diff.
Now we will produce a data diff regardless of the presence of the state
when the configuration is computed during the plan phase.
This fixes#6824.
This means it’s shown correctly in a plan and takes into account any
actions that are dependant on the tainted resource and, vice verse, any
actions that the tainted resource depends on.
So this changes the behaviour from saying this resource is tainted so
just forget about it and make sure it gets deleted in the background,
to saying I want that resource to be recreated (taking into account the
existing resource and it’s place in the graph).
Earlier we had a bug where data resources would not yet removed from the
state during a destroy. This was fixed in cd0c452, and this test will
hopefully make sure it stays fixed.
Adding walkValidate to the EvalTree operations, and removing the
walkValidate guard from the Interpolater.valueModuleVar allows the
values to be interpolated for Validate.
Variables weren't being interpolated during the Input phase, causing a
syntax error on the interpolation string. Adding `walkInput` to the
EvalTree operations prevents skipping the interpolation step.
cd0c452 contained a bug where the creation diff for a data resource was
put into a new local variable within the else block rather than into the
diff variable in the parent scope, causing a null diff to always be
produced.
This restores the expected behavior: a computed data resource appears in
the diff, so it can then be fetched during the apply walk.
Apparently there's been a regression in the creation of data resource
diffs: they aren't showing up in the plan at all.
As a first step to fixing this, this is an intentionally-failing test
that proves it's broken.
Previously the "planDestroy" pass would correctly produce a destroy diff,
but the "apply" pass would just ignore it and make a fresh diff, turning
it back into a "create" because data resources are always eager to
refresh.
Now we consider the previous diff when re-diffing during apply and so
we can preserve the plan to destroy and then ultimately actually "destroy"
the data resource (remove from the state) when we get to ReadDataApply.
This ensures that the state is left empty after "terraform destroy";
previously we would leave behind data resource states.
Building on b10564a, adding tweaks that allow the module var count
search to act recursively, ensuring that a sitaution where something
like var.top gets passed to module middle, as var.middle, and then to
module bottom, as var.bottom, which is then used in a resource count.
A new problem was introduced by the prior fixes for destroy
interpolation messages when resources depend on module variables with
a _count_ attribute, this makes the variable crucial for properly
building the graph - even in destroys. So removing all module variables
from the graph as noops was overzealous.
By borrowing the logic in `DestroyEdgeInclude` we are able to determine
if we need to keep a given module variable relatively easily.
I'd like to overhaul the `Destroy: true` implementation so that it does
not depend on config at all, but I want to continue for now with the
targeted fixes that we can backport into the 0.6 series.
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.
The ResourceAddress struct grows a new "Mode" field to match with
Resource, and its parser learns to recognize the "data." prefix so it
can set that field.
Allows -target to be applied to data sources, although that is arguably
not a very useful thing to do. Other future uses of resource addressing,
like the state plumbing commands, may be better uses of this.
Previously they would get left behind in the state because we had no
support for planning their destruction. Now we'll create a "destroy" plan
and act on it by just producing an empty state on apply, thus ensuring
that the data resources don't get left behind in the state after
everything else is gone.
The handling of data "orphans" is simpler than for managed resources
because the only thing we need to deal with is our own state, and the
validation pass guarantees that by the time we get to refresh or apply
the instance state is no longer needed by any other resources and so
we can safely drop it with no fanfare.
This implements the main behavior of data resources, including both the
early read in cases where the configuration is non-computed and the split
plan/apply read for cases where full configuration can't be known until
apply time.
The key difference between data and managed resources is in their
respective lifecycles. Now the expanded resource EvalTree switches on
the resource mode, generating a different lifecycle for each mode.
For this initial change only managed resources are implemented, using the
same implementation as before; data resources are no-ops. The data
resource implementation will follow in a subsequent change.
data resources are a separate namespace of resources than managed
resources, so we need to call a different provider method depending on
what mode of resource we're visiting.
Managed resources use ValidateResource, while data resources use
ValidateDataSource, since at the provider level of abstraction each
provider has separate sets of resources and data sources respectively.
Once a data resource gets into the state, the state system needs to be
able to parse its id to match it with resources in the configuration.
Since data resources live in a separate namespace than managed resources,
the extra "mode" discriminator is required to specify which namespace
we're talking about, just like we do in the resource configuration.
This is a breaking change to the ResourceProvider interface that adds the
new operations relating to data sources.
DataSources, ValidateDataSource, ReadDataDiff and ReadDataApply are the
data source equivalents of Resources, Validate, Diff and Apply (respectively)
for managed resources.
The diff/apply model seems at first glance a rather strange workflow for
read-only resources, but implementing data resources in this way allows them
to fit cleanly into the standard plan/apply lifecycle in cases where the
configuration contains computed arguments and thus the read must be deferred
until apply time.
Along with breaking the interface, we also fix up the plugin client/server
and helper/schema implementations of it, which are all of the callers
used when provider plugins use helper/schema. This would be a breaking
change for any provider plugin that directly implements the provider
interface, but no known plugins do this and it is not recommended.
At the helper/schema layer the implementer sees ReadDataApply as a "Read",
as opposed to "Create" or "Update" as in the managed resource Apply
implementation. The planning mechanics are handled entirely within
helper/schema, so that complexity is hidden from the provider implementation
itself.
Mitchell Hashimoto