aws_default_internet_gateway is missing

[hashibot]

This issue was originally opened by @xgathos as hashicorp/terraform#16747. It was migrated here as a result of the provider split. The original body of the issue is below.

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Hi
When trying to update the aws_default_route_table, terraform deletes all routes. Therefore we need to create a route for the default internet gateway again. But there is no aws_default_internet_gateway - this makes this task unnecessary complex.

[ewbankkit]

Yes, thought about this when adding aws_default_subnet and aws_default_vpc_dhcp_options, just never got round to it 😄.

[Heiko-san]

Agreed, this would be very helpful

[anthony2025]

We got around it by declaring a data source, but it would still be nice to have a resource for it.

data "aws_internet_gateway" "default" {
  filter {
    name   = "attachment.vpc-id"
    values = ["${aws_default_vpc.vpc.id}"]
  }
}

[ewbankkit]

The reason I haven't done this is that I couldn't see a way to definitively identify the auto-created IGW in the default VPC - The API doesn't indicate whether an IGW is "default" or not.
If we're happy with saying the default IGW is the sole attached IGW in the default VPC then I can implement this.

[ewbankkit]

@xgathos @Heiko-san @anthony2025
I think the most sustainable solution is to use terraform import to import the state of the default IGW.
For example, write some Terraform code:

data "aws_vpc" "default" {
  default = true
}

resource "aws_internet_gateway" "default" {
  vpc_id = "${data.aws_vpc.default.id}"
}

and then import the IGW (ID obtained from AWS Console or by other means):

$ terraform import aws_internet_gateway.default igw-012345678
aws_internet_gateway.default: Importing from ID "igw-012345678"...
aws_internet_gateway.default: Import complete!
  Imported aws_internet_gateway (ID: igw-012345678)
aws_internet_gateway.default: Refreshing state... (ID: igw-012345678)

Import successful!

The resources that were imported are shown above. These resources are now in
your Terraform state and will henceforth be managed by Terraform.

$ terraform plan
Refreshing Terraform state in-memory prior to plan...
The refreshed state will be used to calculate this plan, but will not be
persisted to local or remote state storage.

data.aws_vpc.default: Refreshing state...
aws_internet_gateway.default: Refreshing state... (ID: igw-012345678)

------------------------------------------------------------------------

No changes. Infrastructure is up-to-date.

[anthony2025]

Didn't even know that was possible, thank you for the response!

[saschakettler]

As there can only be one internet gateway attached to a VPC (see VPC Limits), maybe instead of trying to create a new internet gateway and later attaching it to a VPC (which will create a new internet gateway just fine but fail on the attaching step), we could auto-import the existing gateway and reconfigure it according to the configuration (probably with a "reuse_existing" or similar flag to preserve the old behavior by default).

My use case is currently to ensure that all elements of the "Default VPC" have a Name attribute associated with it. This works fine for aws_default_vpc and aws_default_subnet and with the data. aws_internet_gateway workaround it also works for aws_default_route_table and aws_route.

But other than manually importing the aws_internet_gateway I could not find a way to achieve my goal. Unfortunately this leads to a non-default VPC after a terraform destroy, as the internet gateway will be deleted.

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[ghost]

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