There are situations where one may need to write to a set, list, or map
more than once per single TF operation (apply/refresh/etc). In these
cases, further writes using Set (example: d.Set("some_set", newSet))
currently create unstable results in the set writer (the name of the
writer layer that holds the data set by these calls) because old keys
are not being cleared out first.
This bug is most visible when using sets. Example: First write to set
writes elements that have been hashed at 10 and 20, and the second write
writes elements that have been hashed at 30 and 40. While the set length
has been correctly set at 2, since a set is basically a map (as is the
entire map writer) and map results are non-deterministic, reads to this
set will now deliver unstable results in a random but predictable
fashion as the map results are delivered to the caller non-deterministic
- sometimes you may correctly get 30 and 40, but sometimes you may get
10 and 20, or even 10 and 30, etc.
This problem propagates to state which is even more damaging as unstable
results are set to state where they become part of the permanent data
set going forward.
The problem also applies to lists and maps. This is probably more of an
issue with maps as a map can contain any key/value combination and hence
there is no predictable pattern where keys would be overwritten with
default or zero values. This is contrary to complex lists, which has
this problem as well, but since lists are deterministic and the length
of a list properly gets updated during the overwrite, the problem is
masked by the fact that a read will only read to the boundary of the
list, skipping any bad data that may still be available due past the
list boundary.
This update clears the child contents of any set, list, or map before
beginning a new write to address this issue. Tests are included for all
three data types.
This keeps CustomizeDiff from being defined on data sources, where it
would be useless. We just catch this in InternalValidate like the rest
of the CRUD functions that are not used in data sources.
Added some more detailed comments to CustomizeDiff's comments. The new
comments detail how CustomizeDiff will be called in the event of
different scenarios like creating a new resource, diffing an existing
one, diffing an existing resource that has a change that requires a new
resource, and destroy/tainted resources.
Also added similar detail to ForceNew in ResourceDiff.
This should help mitigate any confusion that may come up when using
CustomizeDiff, especially in the ForceNew scenario when the second run
happens with no state.
setDiff does not make use of its new parameter anymore, so it has been
removed. Also, as there is no more SetDiff (exported) function, mentions
of that have been removed from comments too.
This fixes nil pointer issues that could come up if an invalid key was
referenced (ie: not one in the schema). Also ships a helper validation
function to streamline things.
Restoring the naming of this field in the resource back to
CustomizeDiff, as this is generally more descriptive of the process
that's happening, despite the lengthy name.
The old comments said that this interface was API compatible with
terraform.ResourceProvider's Diff method - with the addition of passing
down meta to it, this is no longer the case.
Not too sure if this is really a big deal - schema.Resource never fully
implemented terraform.ResourceProvider, from what I can see, and the
path from Provdier.Diff to Resource.Diff is still pretty clear. Just
wanted to remove an outdated comment.
This could panic if we sent a parent that was actually longer than the
child (should almost never come up, but the guard will make it safe
anyway).
Also fixed a slice style lint warning in UpdatedKeys.
The consensus is that it's a generally better idea to move setting the
functionality of old values completely to the refresh/read process,
hence it's moot to have this function around anymore. This also means we
don't need the old value reader/writer anymore, which simplifies things.
When working on this initially, I think I thought that since NewComputed
values in the diff were empty strings, that it was using the zero value.
After review, it doesn't seem like this is the case - so I have adjusted
NewComputed to pass nil values. There is also a guard now that keeps the
new value writer from accepting computed fields with non-nil values.
To keep with the current convention of most other schema.Resource
functional fields being fairly short, CustomizeDiff has been changed to
"Review". It would be "Diff", however it is already used by existing
functions in schema.Provider and schema.Resource.
Both Destroy and DestroyDeposed are not propagated down the diff stack,
meaning that there is no way we can tell at this point if an instance is
being destroyed or deposed, so this check would never be used.
In this regard, Destroy never runs a diff down the stack at all, and a
deposition check is not run until *after* the provider's diff function
is called. To answer this question and close it off, we could either
determine if a resource is deposed earlier, and propagate that down, or
treat deposed resources like full destroy nodes, and not diff them at
all (but rather making a diff with the only thing in it being
DestroyDeposed flagged).
Added a few more test cases for CustomizeDiff, caught another error in
the process. I think this is ready for review now, and possibly some
real-world testing of the waters by way of porting some resources that
would benefit from the feature.
It's alive! CustomizeDiff logic now has been inserted into the diff
process. The test_resource_with_custom_diff resource provides some basic
testing and a reference implementation.
There should now be plenty of test coverage for this feature via the
tests added for ResourceDiff, and the basic test added to the
schemaMap.Diff test, and the test resource, but more can be added to
test any specific case that comes up otherwise.
As the interface has been specced out for ResourceDiff, the only diff
operation that can function on a non-computed key is ForceNew, and that
is only if a diff exists for that key. As such, allowing the user to
clear keys that cannot be operated on afterwards does not really make
much sense.
Will re-add this function if it is determined it's needed after all on
review.
Final set of coverage for ResourceDiff and bug fixes to correct issues
the test cases brought up.
Will be dropping ClearAll in next commit, as with how this interface is
intended to be used, it does not really make much sense.
This provides a deep copy of a schemaMap, which will be needed for the
diff customization process as ResourceDiff will be able to flag fields
as ForceNew - we don't want to affect the source schema.
In diffString, removed values are marked if the old value is non-nil and
the new value is nil, regardless of if the new value is marked as a
computed value. With the new diff override behaviour, this can lead to
issues where a nil attribute may get inserted into the diff if the new
value has been marked as computed (as the value will be marked as
missing, but computed).
This propagates into finalizeDiff in some respects because even if
NewComputed is manually set in the diff that gets passed in, it is
ignored, and the schema becomes the only source of truth. Since our new
diff behaviour is mainly designed to be supported on computed keys only,
it stands to reason that we there will be a time where we want to set a
diff as NewComputed on a key, and see that change in the diff.
These two small changes makes that happen. No regressions in tests have
been observed via this change, so it seems safe and non-invasive.
The beginning of tests for SetNew. Noticed that removed values are not
logged for computed keys in a diff - not too sure if that is going to be
a problem (possibly not as GetChange in ResourceData should still
reference state for the old value). I came on this most notably in the
"TestSetNew/complex-ish_set_diff" test, for reference.
More tests pending for other functions for coverage of other functions
and test cases as defined in #8769.
This ensures that when we hook this into the main diff logic, that we
can just re-diff the keys that are modified, ensuring that the diff is
not re-run on keys that were not touched, or on keys that were
intentionally removed.
This should complete the feature set of the prototype. This function
removes a specific key from the existing diff, preventing conflicts.
Further functionality might be needed to make this behave as expected,
namely ensuring that we don't re-process the whole diff after the
CustomizeDiffFunc runs.
This new prototype removes the dependence on a underlying ResourceData,
moving several items up to ensure an approach that more matches
ResourceData. Namely, we create our own MultiLevelFieldReader that
also layers updated diff values on top. New values use a small
re-implementation of the MapFieldWriter/Reader that allows computed
values to be set.
The assumption here now is that a second diff will happen after the
first one is done, processing the new values set in the 2 new
reader/writer levels and updating the diff as necessary.
This adds a new object, ResourceDiff, to the schema package. This
object, in conjunction with a function defined in CustomizeDiff in the
resource schema, allows for the in-flight customization of a Terraform
diff. This helps support use cases such as when there are necessary
changes to a resource that cannot be detected in config, such as via
computed fields (most of the utility in this object works on computed
fields only). It also allows for a wholesale wipe of the diff to allow
for diff logic completely offloaded to an external API, if it is a
better use case for a specific provider.
As part of this work, many internal diff functions have been moved to
use a special resourceDiffer interface, to allow for shared
functionality between ResourceDiff and ResourceData. This may be
extended to the DiffSuppressFunc as well which would restrict use of
ResourceData in DiffSuppressFunc to generally read-only fields.
This work is not yet in its final state - CustomizeDiff is not yet
implemented in the general diff workflow, new functions may be added
(notably Clear() for a single key), and functionality may be altered.
Tests will follow as well.
Update the command package to use the new module storage. Move the old
command output strings into the module storage itself. This could be
moved back later either by using ui callbacks, or designing a module
storage interface once we know what the final requirements will look
like.
In order to parse provider, resource and data source configuration from
HCL2 config files, we need to know the relevant configuration schema.
This new method allows Terraform Core to request these from a provider.
This is a breaking change to this interface, so all of its implementers
in this package are updated too. This includes concrete implementations
of the new method in helper/schema that use the schema conversion code
added in an earlier commit to produce a configschema.Block automatically.
Plugins compiled against prior versions of helper/schema will not have
support for this method, and so calls to them will fail. Callers of
this new method will therefore need to sniff for support using the
SchemaAvailable field added to both ResourceType and DataSource.
This careful handling will need to persist until next time we increment
the plugin protocol version, at which point we can make the breaking
change of requiring this information to be available.
Uses Levenshtein distance to decide if the input is similar enough to one
of the given suggestions, and returns that suggestion if so.
The distance threshold of three was arrived at experimentally, and has
no objective basis.
We don't currently have any need for this information, but we're
propagating it out of helper/schema here pre-emptively so that once we
later have a use for it we will not need to rebuild the providers to gain
access to it.
The long-term expected use-case for this is to have Terraform Core use
static analysis techniques to trace the path of sensitive data through
interpolations so that intermediate results can be flagged as sensitive
too, but we have a lot more work to do before such a thing would actually
be possible.
As part of moving to the next-generation HCL implementation,
Terraform Core is getting its own representation of configuration schema
that is tailored for configuration-processing use-cases. The capabilities
of this are a subset of the helper/schema model primarily concerned with
the configuration structure and value types, leaving detailed validation
and defaults for helper/schema to still solve.
These new methods allow mechanical creation of a schema in the new Core
schema model from a schema expressed in the helper/schema model. This is
not yet used as of this commit, but will be used later to implement some
new ResourceProvider methods that will allow core to obtain the schema
for provider, resource and data source configuration while remaining
source-compatible with existing provider implementations.
This adds NoZeroValues, a small SchemaValidateFunc that checks that a
defined value is not a zero value. It's useful for situations where you
want to keep someone from explicitly entering a zero value (ie:
literally "0", or an empty string) on a required field, and want to
catch it in the validation stage, versus during apply using GetOk.
Add an ImportStateIdFunc field to the ImportState testing functionality.
This will allow for more powerful generation of complex import state IDs
that can't be accomplished by ImportStateId or ImportStateIdPrefix
themselves.
Chris Marchesi