Amazon lowercases db_subnet_group_name

[SamBarker]

I'm trying to work out why terraform continually destroys and adds my DB instances. I finally spotted that its because I'm using db_subnet_group_name, which forces a new resource.

I've marked the DB instances as depending on the aws_db_subnet_group, but the aws_db_subnet_group is not being marked for change.

Looking at the RDS instance in the AWS console Amazon have lowercased the group name! My config looks like:

resource "aws_db_subnet_group" "db_subnet_group" {
  name = "${var.envType} DB"
  description = "${var.envType} DB"
  subnet_ids = [
    "${aws_subnet.rds-a.id}",
    "${aws_subnet.rds-b.id}"]
}

resource "aws_db_instance" "modeA-db" {
  identifier = "modeA_db"
  allocated_storage = "8"
  engine = "mysql"
  engine_version = "5.6.22"
  instance_class = "db.m.large"
  username = "user"
  password = "test123"
  db_subnet_group_name = "${var.envType} DB"
  maintenance_window = "sun:00:30-sun:01:00"
  storage_type = "standard"
  port = "${var.db-port}"
  publicly_accessible = false
  multi_az = false
  availability_zone = "${var.zone-a}"
  vpc_security_group_ids = [
    "${aws_security_group.rds-demo-db.id}",
    "${aws_security_group.rds-live-db.id}"]

  depends_on = "aws_db_subnet_group.db_subnet_group"
}

Additionally it would be good if the aws_db_subnet_group exposed its name as an output.

I'm going to update my config to use lowecase names but I think terraform should lowercase the group name automatically

[radeksimko]

I remember having very similar issues in some order RDS resources.

I think terraform should lowercase the group name automatically

I don't think Terraform should be as magic as AWS API 😃 and do things user may not expect.
I'd rather see validation giving error, once we have the support for validation in place.

[SamBarker]

While I agree that terraform shouldn't do magic I do think it should behave
consistently with AWS which does mean enforcing lowercase names.

As I see it the problem with just doing validation is that the instances
get destroyed and recreated whithout a change which is obviously not good
news if there is data in them.
On 13/06/2015 2:25 PM, "Radek Simko" notifications@github.com wrote:

I remember having very similar issues in some order RDS resources.

I think terraform should lowercase the group name automatically

I don't think Terraform should be as magic as AWS API [image: 😃]
and do things user may not expect.
I'd rather see validation giving error, once we have the support for
validation #2265 in place.

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[radeksimko]

As I see it the problem with just doing validation is that the instances
get destroyed and recreated whithout a change which is obviously not good
news if there is data in them.

I'm not sure I get that, why should instances get even touched, when validation prevents any further action if the name isn't lowercase?

[SamBarker]

Sorry just flown from NZ to UK not thinking clearly enough. As long as the
validation actually prevents a the diff being generated then yes it does
the job.
On 13/06/2015 8:24 PM, "Radek Simko" notifications@github.com wrote:

As I see it the problem with just doing validation is that the instances
get destroyed and recreated whithout a change which is obviously not good
news if there is data in them.

I'm not sure I get that, why should instances get even touched, when
validation prevents any further action if the name isn't lowercase?

—
Reply to this email directly or view it on GitHub
#2320 (comment)
.

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414198. This email, its attachments and any rights attaching hereto are
confidential and intended exclusively for the person to whom the email is
addressed. If you are not the intended recipient, do not read, copy,
disclose or use the contents in any way. Please notify the sender by return
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[radeksimko]

@SamBarker No worries 😃 it happens to me from time to time too.

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