[AWS] NAT Gateway diff error

[pporada-gl]

I built terraform from the develop branch and have encountered the following error.

Terraform version: 0.6.9 dev 757a42704e0fd550ecf2d5e84d076517bf85e339

* aws_nat_gateway.gateway.0: diffs didn't match during apply. This is a bug with Terraform and should be reported.

My environment has 3 availability zones and only 2 NAT gateways are being built. Every subsequent apply also fails to build the missing NAT gateway.

Here is my file structure

.
├── modules/
│   └── aws/
│       ├── data/
│       │   ├── data.tf
│       │   └── elasticache/
│       │       └── elasticache.tf
│       ├── dns/
│       │   └── dns.tf
│       ├── network/
│       │   ├── bastion/
│       │   │   └── bastion.tf
│       │   ├── nat/
│       │   │   └── nat.tf
│       │   ├── network.tf
│       │   ├── private_network/
│       │   │   └── private_network.tf
│       │   ├── public_network/
│       │   │   └── public_network.tf
│       │   └── vpc/
│               └── vpc.tf
└── providers/
    └── aws/
        ├── Makefile
        ├── README.md
        ├── environments/
        │   └── staging/
        │       └── staging.tfvars
        ├── main.tf
        └── terraform.tfstate.backup

nat.tf

variable "public_subnets" { }
variable "subnet_ids" { }

resource "aws_eip" "nat_gateway" {
    count   = "${length(split(",", var.public_subnets))}"
    vpc     = true
}

resource "aws_nat_gateway" "gateway" {
    count         = "${length(split(",", var.public_subnets))}"
    subnet_id     = "${element(split(",", var.subnet_ids), count.index)}"
    allocation_id = "${element(aws_eip.nat_gateway.*.id, count.index)}"
}

Attached is a debug log and screenshot of the aws console. Let me know what else you need from me.
tf.log.zip

[pporada-gl]

In my nat.tf, if I try to use subnet_ids for interpolation instead of public_subnets, I receive this error which seems identical to #3888

Errors:

  * strconv.ParseInt: parsing "${length(split(\",\", var.subnet_ids))}": invalid syntax

variable "public_subnets" { }
variable "subnet_ids" { }

resource "aws_eip" "nat_gateway" {
    count   = "${length(split(",", var.subnet_ids))}"
    vpc     = true
}

resource "aws_nat_gateway" "gateway" {
    count         = "${length(split(",", var.subnet_ids))}"
    subnet_id     = "${element(split(",", var.subnet_ids), count.index)}"
    allocation_id = "${element(aws_eip.nat_gateway.*.id, count.index)}"
}

[radeksimko]

Cutting out the interesting part of the log:

2015/12/22 15:23:37 [ERROR] aws_nat_gateway.gateway.0: diffs didn't match
2015/12/22 15:23:37 [ERROR] aws_nat_gateway.gateway.0: reason: attribute mismatch: allocation_id
2015/12/22 15:23:37 [ERROR] aws_nat_gateway.gateway.0: diff one: *terraform.InstanceDiff{Attributes:map[string]*terraform.ResourceAttrDiff{"private_ip":*terraform.ResourceAttrDiff{Old:"", New:"", NewComputed:true, NewRemoved:false, NewExtra:interface {}(nil), RequiresNew:false, Type:0x0}, "public_ip":*terraform.ResourceAttrDiff{Old:"", New:"", NewComputed:true, NewRemoved:false, NewExtra:interface {}(nil), RequiresNew:false, Type:0x0}, "allocation_id":*terraform.ResourceAttrDiff{Old:"", New:"${element(split(\",\", aws_eip.nat_gateway.*.id), count.index)}", NewComputed:false, NewRemoved:false, NewExtra:interface {}(nil), RequiresNew:true, Type:0x0}, "subnet_id":*terraform.ResourceAttrDiff{Old:"", New:"${element(split(\",\", var.subnet_ids), count.index)}", NewComputed:false, NewRemoved:false, NewExtra:interface {}(nil), RequiresNew:true, Type:0x0}, "network_interface_id":*terraform.ResourceAttrDiff{Old:"", New:"", NewComputed:true, NewRemoved:false, NewExtra:interface {}(nil), RequiresNew:false, Type:0x0}}, Destroy:false, DestroyTainted:false}
2015/12/22 15:23:37 [ERROR] aws_nat_gateway.gateway.0: diff two: *terraform.InstanceDiff{Attributes:map[string]*terraform.ResourceAttrDiff{"subnet_id":*terraform.ResourceAttrDiff{Old:"", New:"subnet-683cd730", NewComputed:false, NewRemoved:false, NewExtra:interface {}(nil), RequiresNew:true, Type:0x0}, "network_interface_id":*terraform.ResourceAttrDiff{Old:"", New:"", NewComputed:true, NewRemoved:false, NewExtra:interface {}(nil), RequiresNew:false, Type:0x0}, "private_ip":*terraform.ResourceAttrDiff{Old:"", New:"", NewComputed:true, NewRemoved:false, NewExtra:interface {}(nil), RequiresNew:false, Type:0x0}, "public_ip":*terraform.ResourceAttrDiff{Old:"", New:"", NewComputed:true, NewRemoved:false, NewExtra:interface {}(nil), RequiresNew:false, Type:0x0}}, Destroy:false, DestroyTainted:false}

which makes me think this is very likely related to #3888 (i.e. you're probably right)

[mitchellh]

Yes, this is a manifestation of #3888, centralizing there

[ghost]

I'm going to lock this issue because it has been closed for 30 days ⏳. This helps our maintainers find and focus on the active issues.

If you have found a problem that seems similar to this, please open a new issue and complete the issue template so we can capture all the details necessary to investigate further.