data.aws_iam_policy_document.override_policy_documents causes panic if [""] used

[patdowney]

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Terraform CLI and Terraform AWS Provider Version

 terraform-iam-test % terraform -v
Terraform v1.1.8
on darwin_amd64
+ provider registry.terraform.io/hashicorp/aws v4.14.0

Affected Resource(s)

• aws_iam_policy_document

Terraform Configuration Files

Please include all Terraform configurations required to reproduce the bug. Bug reports without a functional reproduction may be closed without investigation.

provider "aws" {
  skip_metadata_api_check = true
  skip_get_ec2_platforms = true
  skip_credentials_validation = true
  skip_region_validation = true
  skip_requesting_account_id = true
}

data "aws_iam_policy_document" "test" {
  override_policy_documents = [""]
}

(Also available at https://gist.github.com/patdowney/a6f9355b7e50253116ca67f2fe4d8977#file-test-tf)

Debug Output

https://gist.github.com/patdowney/a6f9355b7e50253116ca67f2fe4d8977#file-debug-log

Panic Output

https://gist.github.com/patdowney/a6f9355b7e50253116ca67f2fe4d8977#file-crash-log

Expected Behavior

terraform should have responded with an error, like it does if [null] is used

e.g.

Error: Null value found in list
│
│   with data.aws_iam_policy_document.test,
│   on test.tf line 3, in data "aws_iam_policy_document" "test":
│    3:   override_policy_documents = [null]
│
│ Null values are not allowed for this attribute value.

Actual Behavior

terraform AWS provider crashes

Steps to Reproduce

1. terraform plan

Important Factoids

References

• #0000

[ewbankkit]

Stack trace from the terraform-provider-aws_v4.14.0_x5 plugin:

panic: interface conversion: interface {} is nil, not string

goroutine 83 [running]:
github.com/hashicorp/terraform-provider-aws/internal/service/iam.dataSourcePolicyDocumentRead(0x68, {0x80, 0x136005b8})
data "aws_iam_policy_document" "test" {
	github.com/hashicorp/terraform-provider-aws/internal/service/iam/policy_document_data_source.go:253 +0x605
github.com/hashicorp/terraform-plugin-sdk/v2/helper/schema.(*Resource).read(0xb0b6f00, {0xb0b6f00, 0xc002b1c330}, 0xd, {0x8b67260, 0xc000ca6000})
	github.com/hashicorp/terraform-plugin-sdk/v2@v2.16.0/helper/schema/resource.go:712 +0x178
github.com/hashicorp/terraform-plugin-sdk/v2/helper/schema.(*Resource).ReadDataApply(0xc0006d0700, {0xb0b6f00, 0xc002b1c330}, 0xc002f5c980, {0x8b67260, 0xc000ca6000})
	github.com/hashicorp/terraform-plugin-sdk/v2@v2.16.0/helper/schema/resource.go:943 +0x145
github.com/hashicorp/terraform-plugin-sdk/v2/helper/schema.(*GRPCProviderServer).ReadDataSource(0xc00012b128, {0xb0b6e58, 0xc001192cc0}, 0xc002f20520)
	github.com/hashicorp/terraform-plugin-sdk/v2@v2.16.0/helper/schema/grpc_provider.go:1179 +0x408
github.com/hashicorp/terraform-plugin-go/tfprotov5/tf5server.(*server).ReadDataSource(0xc00190edc0, {0xb0b6f00, 0xc002c8db90}, 0xc002f220a0)
	github.com/hashicorp/terraform-plugin-go@v0.9.0/tfprotov5/tf5server/server.go:657 +0x45f
github.com/hashicorp/terraform-plugin-go/tfprotov5/internal/tfplugin5._Provider_ReadDataSource_Handler({0x9d61ee0, 0xc00190edc0}, {0xb0b6f00, 0xc002c8db90}, 0xc002ca7020, 0x0)
	github.com/hashicorp/terraform-plugin-go@v0.9.0/tfprotov5/internal/tfplugin5/tfplugin5_grpc.pb.go:421 +0x170
google.golang.org/grpc.(*Server).processUnaryRPC(0xc0001fe540, {0xb1c2510, 0xc0000b2340}, 0xc002f66000, 0xc00191ac90, 0x10dafe90, 0x0)
	google.golang.org/grpc@v1.45.0/server.go:1282 +0xccf
google.golang.org/grpc.(*Server).handleStream(0xc0001fe540, {0xb1c2510, 0xc0000b2340}, 0xc002f66000, 0x0)
	google.golang.org/grpc@v1.45.0/server.go:1619 +0xa2a
google.golang.org/grpc.(*Server).serveStreams.func1.2()
	google.golang.org/grpc@v1.45.0/server.go:921 +0x98
created by google.golang.org/grpc.(*Server).serveStreams.func1
	google.golang.org/grpc@v1.45.0/server.go:919 +0x294

[jar-b]

closed by #27055

[github-actions]

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