inconsistent map element types - defaults inside optional object

[liamcervante]

Terraform Version

1.3.4

Terraform Configuration Files

variable "domains" {
  type = map(object({
    rules = map(object({
      backend = optional(string)
      url_redirect = optional(object({
        destination   = string
        preserve_path = optional(bool, true)
      }))
    }))
  }))
}

domains = {
  "one" = {
    rules = {
      "/" = {
        "backend" = "testing"
      }
    }
  }

  "two" = {
    rules = {
      "/" = {
        url_redirect = {
            destination   = "https://redirect.fake.domain.com/alertmanager"
            preserve_path = false
        }
      }
    }
  }
}

Debug Output

n/a

Expected Behavior

no crash

Actual Behavior

!!!!!!!!!!!!!!!!!!!!!!!!!!! TERRAFORM CRASH !!!!!!!!!!!!!!!!!!!!!!!!!!!!


inconsistent map element types (cty.Object(map[string]cty.Type{"rules":cty.Map(cty.Object(map[string]cty.Type{"backend":cty.String, "url_redirect":cty.Object(map[string]cty.Type{"preserve_pa
th":cty.Bool})}))}) then cty.Object(map[string]cty.Type{"rules":cty.Map(cty.Object(map[string]cty.Type{"backend":cty.String, "url_redirect":cty.Object(map[string]cty.Type{"destination":cty.S
tring, "preserve_path":cty.Bool})}))}))
goroutine 55 [running]:
runtime/debug.Stack()
        /usr/local/go/src/runtime/debug/stack.go:24 +0x64
runtime/debug.PrintStack()
        /usr/local/go/src/runtime/debug/stack.go:16 +0x1c
github.com/hashicorp/terraform/internal/logging.PanicHandler()
        /Users/distiller/project/project/internal/logging/panic.go:55 +0x170
panic({0x1025d5500, 0x140005be980})
        /usr/local/go/src/runtime/panic.go:884 +0x204
github.com/zclconf/go-cty/cty.MapVal(0x14000634ed8)
        /Users/distiller/go/pkg/mod/github.com/zclconf/[email protected]/cty/value_init.go:221 +0x488
github.com/zclconf/go-cty/cty.transform({0x0?, 0x0, 0x0}, {{{0x1029da648?, 0x140005be640?}}, {0x10260db00?, 0x140005c0cf0?}}, {0x1029c1a80, 0x14000556178})
        /Users/distiller/go/pkg/mod/github.com/zclconf/[email protected]/cty/walk.go:204 +0x92c
github.com/zclconf/go-cty/cty.TransformWithTransformer(...)
        /Users/distiller/go/pkg/mod/github.com/zclconf/[email protected]/cty/walk.go:130
github.com/hashicorp/hcl/v2/ext/typeexpr.(*Defaults).Apply(0x1400083f840?, {{{0x1029da648?, 0x140005be640?}}, {0x10260db00?, 0x140005c0cf0?}})
        /Users/distiller/go/pkg/mod/github.com/hashicorp/hcl/[email protected]/ext/typeexpr/defaults.go:38 +0x9c
github.com/hashicorp/terraform/internal/terraform.prepareFinalInputVariableValue({{0x0, 0x0, 0x0}, {{}, {0x1400055c180, 0x7}}}, 0x1400042ee70, 0x1400097b6c0)
        /Users/distiller/project/project/internal/terraform/eval_variable.go:140 +0x854
github.com/hashicorp/terraform/internal/terraform.(*NodeRootVariable).Execute(0x1400083fb80, {0x1029eea38, 0x140006380e0}, 0xc0?)
        /Users/distiller/project/project/internal/terraform/node_root_variable.go:82 +0x168
github.com/hashicorp/terraform/internal/terraform.(*ContextGraphWalker).Execute(0x1400027ec30, {0x1029eea38, 0x140006380e0}, {0x12beff8f8, 0x1400083fb80})
        /Users/distiller/project/project/internal/terraform/graph_walk_context.go:136 +0xa8
github.com/hashicorp/terraform/internal/terraform.(*Graph).walk.func1({0x102744f20, 0x1400083fb80})
        /Users/distiller/project/project/internal/terraform/graph.go:74 +0x208
github.com/hashicorp/terraform/internal/dag.(*Walker).walkVertex(0x14000705140, {0x102744f20, 0x1400083fb80}, 0x1400090fb00)
        /Users/distiller/project/project/internal/dag/walk.go:381 +0x2e0
created by github.com/hashicorp/terraform/internal/dag.(*Walker).Update
        /Users/distiller/project/project/internal/dag/walk.go:304 +0xbf0

Steps to Reproduce

terraform init
terraform apply

Additional Context

No response

References

#32152

[liamcervante]

This is an issue in the HCL defaults package. Essentially it tries to create a value for preserve_path inside the non-existent url_redirect object in the first entry in the map. Since destination does not have a default value it creates an object of the wrong type, and then when it tries reconcile the surrounding map with the new default values we get the crash due to inconsistent types (one object has both destination and preserve_path while the other only has preserve_path).

I think the correct behaviour here would be to just leave the whole url_redirect object as null and not attempt to insert default values into null objects.

[liamcervante]

A workaround for this is to provide an default value for the destination field as well as the preserve_path field OR to provide a default value for the whole url_redirect object.

This is still a bug, but you might be able to make progress with the workaround until we can fix it.

[github-actions]

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