opentofu/lang/data.go
Martin Atkins 3b49028b77 core: Static-validate resource references against schemas
In the initial move to HCL2 we started relying only on full expression
evaluation to catch attribute errors, but that's not sufficient for
resource attributes in practice because during validation we can't know
yet whether a resource reference evaluates to a single object or to a
list of objects (if count is set).

To address this, here we reinstate some static validation of resource
references by analyzing directly the reference objects, disregarding any
instance index if present, and produce errors if the remaining subsequent
traversal steps do not correspond to items within the resource type
schema.

This also allows us to produce some more specialized error messages for
certain situations. In particular, we can recognize a reference like
aws_instance.foo.count, which in 0.11 and prior was a weird special case
for determining the count value of a resource block, and offer a helpful
error showing the new length(aws_instance.foo) usage pattern.

This eventually delegates to the static traversal validation logic that
was added to the configschema package in a previous commit, which also
includes some specialized error messages that distinguish between
attributes and block types in the schema so that the errors relate more
directly to constructs the user can see in the configuration.

In future we could potentially move more of the checks from the dynamic
schema construction step to the static validation step, but resources
are the reference type that most needs this immediately due to the
ambiguity caused by the instance indexing syntax. We can safely refactor
other reference types to be statically validated in later releases.

This is verified by two pre-existing context validate tests which we
temporarily disabled during earlier work (now re-enabled) and also by a
new validate test aimed specifically at the special case for the "count"
attribute.
2018-11-26 08:25:03 -08:00

34 lines
1.7 KiB
Go

package lang
import (
"github.com/hashicorp/terraform/addrs"
"github.com/hashicorp/terraform/tfdiags"
"github.com/zclconf/go-cty/cty"
)
// Data is an interface whose implementations can provide cty.Value
// representations of objects identified by referenceable addresses from
// the addrs package.
//
// This interface will grow each time a new type of reference is added, and so
// implementations outside of the Terraform codebases are not advised.
//
// Each method returns a suitable value and optionally some diagnostics. If the
// returned diagnostics contains errors then the type of the returned value is
// used to construct an unknown value of the same type which is then used in
// place of the requested object so that type checking can still proceed. In
// cases where it's not possible to even determine a suitable result type,
// cty.DynamicVal is returned along with errors describing the problem.
type Data interface {
StaticValidateReferences(refs []*addrs.Reference, self addrs.Referenceable) tfdiags.Diagnostics
GetCountAttr(addrs.CountAttr, tfdiags.SourceRange) (cty.Value, tfdiags.Diagnostics)
GetResourceInstance(addrs.ResourceInstance, tfdiags.SourceRange) (cty.Value, tfdiags.Diagnostics)
GetLocalValue(addrs.LocalValue, tfdiags.SourceRange) (cty.Value, tfdiags.Diagnostics)
GetModuleInstance(addrs.ModuleCallInstance, tfdiags.SourceRange) (cty.Value, tfdiags.Diagnostics)
GetModuleInstanceOutput(addrs.ModuleCallOutput, tfdiags.SourceRange) (cty.Value, tfdiags.Diagnostics)
GetPathAttr(addrs.PathAttr, tfdiags.SourceRange) (cty.Value, tfdiags.Diagnostics)
GetTerraformAttr(addrs.TerraformAttr, tfdiags.SourceRange) (cty.Value, tfdiags.Diagnostics)
GetInputVariable(addrs.InputVariable, tfdiags.SourceRange) (cty.Value, tfdiags.Diagnostics)
}