Crash with AWS provider creating aws_instance

[rberlind]

Terraform Version

$terraform -v
Terraform v0.12.0-alpha1
+ provider.aws v1.40.0-5-g4f24bc8b7

Terraform Configuration Files

terraform {
  required_version = ">= 0.12.0"
}

provider "aws" {
  region = var.aws_region
}

resource "aws_instance" "ubuntu" {
  ami                         = var.ami_id
  instance_type               = var.instance_type
  availability_zone           = format("%sb", var.aws_region)
  associate_public_ip_address = "true"
  tags = {
    Name  = var.name
    owner = "[email protected]"
    ttl   = "-1"
  }
}

Debug Output

https://gist.github.com/rberlind/fbac8ad21e592649e939fa89b8874c6e

Crash Output

https://gist.github.com/rberlind/b5b8dc06fc289725a8a2fe6b0801b3ea

Expected Behavior

Apply should have worked.

Actual Behavior

Crash.

Steps to Reproduce

1. terraform init
2. terraform apply

Additional Context

The panic message I saw in the crash ("can't use ElementIterator on null value") is the same as in #19152 even though I used the AWS provider and that issue used the Google provider.

Note that I did use the AWS provider that was bundled with the Terraform 0.12 alpha-1

References

Possibly #19152

[rberlind]

I should note that I was able to use the AWS provider to create a VPC with some simple code:

provider "aws" {
  region = "us-east-1"
}

resource "aws_vpc" "main" {
  cidr_block = "10.0.0.0/16"
  tags = {
    Name = "roger-test-0.12"
  }
}

[mitchellh]

Noting that this is the same crash as #19152.

[rberlind]

Strangely, my AWS example works if I add a credit_specification block at the end:

terraform {
  required_version = ">= 0.12.0"
}

provider "aws" {
  region = var.aws_region
}

resource "aws_instance" "ubuntu" {
  ami           = var.ami_id
  instance_type = var.instance_type
  availability_zone = format("%sb", var.aws_region)
  tags = {
    Name  = var.name
    owner = "[email protected]"
    ttl   = "-1"
  }
  credit_specification {
    cpu_credits = "unlimited"
  }
}

I discovered this accidentally while implementing this example. That example works with either the credit_specification or network_interface block or both of them.

[mitchellh]

I just verified that this is fixed with #19201

[mitchellh]

(Note that it requires a rebuilt AWS provider against an updated Terraform vendor)

[rberlind]

Thanks @mitchellh

[rberlind]

I can verify this is fixed in 0.12 alpha-2

[ghost]

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