no matching subnet found for vpc with id vpc

3
votes

I am using data resources (Terraform .12) to find the subnet_id within the vpc and finally create ec2 instance. The VPC is getting created succesfully but I get the following error :

Error: no matching subnet found for vpc with id vpc-03a71967237294efe

However, If execute again it works.

module.my_vpc.aws_vpc.primary_vpc: Creating...

module.my_vpc.aws_vpc.primary_vpc: Creation complete after 3s [id=vpc-03a71967237294efe]

Error: no matching subnet found for vpc with id vpc-03a71967237294efe 

Main.tf
   vpc.tf
   public_subnet.tf
   ec2.tf

Here is the reproducible code:

Main.tf

provider "aws" {
  region = "us-east-1"
  profile = "work"
  shared_credentials_file=">>>>>>>>>>"
}

module "my_vpc" {
  source = "../mod/vpc"
  vpc_cidr = "10.0.0.0/16"
}

module "pub_sub" {
  source = "../mod/pub_sub"  
  vpc_id  = "${module.my_vpc.id}"
} 

module "ec2" { 
  source = "../mod/instances"  
  vpc_id  = "${module.my_vpc.id}" 
}

public_subnet.tf

  variable "sub_cdr" {
  type="list"
  default=["10.0.0.0/28", "10.0.0.16/28"]
}
variable "azs" {
type="list"
default=["us-east-1a","us-east-1b"]
}


data "aws_availability_zones" azs {}

variable "vpc_id" { }

resource aws_subnet "public_subnet"{
count=2
vpc_id=var.vpc_id
cidr_block=var.sub_cdr[count.index]
availability_zone=data.aws_availability_zones.azs.names[count.index]
tags= {Name = "pub-sub-${count.index + 1}"} 
}

output "pub_sub_id" {
  value = aws_subnet.public_subnet.*.id
}

ec2.tf 

variable "vpc_id" { }

variable "instance_count" {
  default=1
}

data "aws_subnet_ids" "public" {
  vpc_id = var.vpc_id
  tags = {
    Name = "*pub-sub*"
  }

}

resource "aws_security_group" "pub_sg" {
  vpc_id = "${var.vpc_id}"
  name = "public-sg"
  ingress {
    from_port = 22
    protocol = "tcp"
    to_port = 22
    cidr_blocks = ["0.0.0.0/0"]
  }

  egress {
    from_port = 0
    protocol = "-1"
    to_port = 0
    cidr_blocks = ["0.0.0.0/0"]
  }
}

resource "aws_instance" "web-srvs" {
count=1
ami = "ami-035b3c7efe6d061d5"
instance_type = "t2.nano"
key_name="dell-dev"
subnet_id = element(tolist(data.aws_subnet_ids.public.ids), count.index)
vpc_security_group_ids = ["${aws_security_group.pub_sg.id}"]
associate_public_ip_address=true
tags = { 
     CountIndex = "${var.instance_count == "0" ? "" : format("%02d", count.index + 1)}"  
   }
}

Any help is highly appreciated.

1
amazon-web-servicesresourcesterraformsubnetvpc
Are you attempting to retrieve a subnet that is being created later and does not exist yet? – Matt Schuchard
module.pub_sub.aws_subnet.public_subnet[1]: Creation complete after 1s [id=subnet-0f988a979b1b3a491] module.pub_sub.aws_subnet.public_subnet[0]: Creation complete after 1s [id=subnet-039fc6aa57e3351ea] Error: no matching subnet found for vpc with id vpc-08ba53586e95d7260 – Judi
Thanks for your reply. Subnet is getting created fine as you can see above. As mentioned earlier. However, If run terraform apply again it works ! – Judi
Can you share a more fully complete minimal reproducible example? As Matt mentioned it looks like you have a subnet resource and a data source in the same context so when Terraform runs the first time it attempts to look up a subnet and create it at the same time so the data source fails. Rerunning it would then work fine. It's possible you can ditch the data source entirely if you show the full code. – ydaetskcoR
I have edited the main section and added the code to produce the error. If you run twice it works. Is it module dependency ? Appreciate your help. – Judi

1 Answers

1
votes

I had the same issue and found that adding a depends_on clause in the aws aws_subnet_ids data component addressed it for me.