Terrraform: create aws vpc in different regions based on region input variable

Question

I'm trying to create an aws vpc using terraform aws vpc module - and it should be created in different region depending on input variable.

Here is what I got in main.tf file:

provider "aws" {
  region  = var.region
}


module "vpc" {
  source = "terraform-aws-modules/vpc/aws"

  name = local.workspace["vpc_name"]
  cidr = local.workspace["vpc_cidr"]

  azs             = local.workspace["vpc_azs"]
  private_subnets = local.workspace["vpc_private_subnets"]
  public_subnets  = local.workspace["vpc_public_subnets"]```

And here is what I have in variables.tf:

variable "region" {}
...
locals {
  env = {
    default = {}
...
    app-dev = {
      env_name                      = "dev"
      vpc_name                      = "app-vpc-dev"
      vpc_cidr                      = "10.12.0.0/16"
      vpc_azs                       = ["us-west-2a", "us-west-2b"]
      vpc_private_subnets           = ["10.12.60.0/24", "10.12.61.0/24"]
      vpc_public_subnets            = ["10.12.160.0/24", "10.12.161.0/24"]
    }
  }
  environmentvars = contains(keys(local.env), terraform.workspace) ? terraform.workspace : "default"
  workspace       = merge(local.env["default"], local.env[local.environmentvars])
}

And then I want to apply it with different variable,like:

terraform apply -var="region=us-west-2"

or

terraform apply -var="region=eu-west-2"

And it should create vpc in different region. So "us-west-2a", "us-west-2b" in variables should be substituted with "eu-west-2a", "eu-west-2b". Is this possible?

I was trying to do it this way:

Add data aws_availability_zones to main.tf:

data "aws_availability_zones" "available" {
  state = "available"
}

change vpc_azs variable in variable.tf with:

vpc_azs = "${data.aws_availability_zones.available.names}"

But it doesn't work - it adds resources in one region and when adding to another one, tries to replace route tables instead of creating new one.

Plan: 24 to add, 0 to change, 4 to destroy.
  # module.vpc.aws_route_table_association.private[0] must be replaced
-/+ resource "aws_route_table_association" "private" {
      ~ id             = "rtbassoc-035aef7e37dad1ac1" -> (known after apply)
      ~ route_table_id = "rtb-026bfeee8c7e042a6" -> (known after apply)
      ~ subnet_id      = "subnet-070f46911b6ac5d20" -> (known after apply) # forces replacement
    }
  # module.vpc.aws_route_table_association.private[1] must be replaced
-/+ resource "aws_route_table_association" "private" {
      ~ id             = "rtbassoc-079f04e405eca2ed3" -> (known after apply)
      ~ route_table_id = "rtb-0aabe71401689c1be" -> (known after apply)
      ~ subnet_id      = "subnet-03fe27c23fd3178f3" -> (known after apply) # forces replacement
    }
  # module.vpc.aws_route_table_association.public[0] must be replaced
-/+ resource "aws_route_table_association" "public" {
      ~ id             = "rtbassoc-02af1c10bea83bdd2" -> (known after apply)
      ~ route_table_id = "rtb-000cfffca8956073c" -> (known after apply)
      ~ subnet_id      = "subnet-0951342807d06a0f3" -> (known after apply) # forces replacement
    }
  # module.vpc.aws_route_table_association.public[1] must be replaced
-/+ resource "aws_route_table_association" "public" {
      ~ id             = "rtbassoc-051ff11315ef42d31" -> (known after apply)
      ~ route_table_id = "rtb-000cfffca8956073c" -> (known after apply)
      ~ subnet_id      = "subnet-0da8a20c3f25fcc44" -> (known after apply) # forces replacement
    }

So maybe this can be done in some other way?

You need a separate state file for each region. There are a few different options for managing multiple environments from a single terraform project eg terraform.io/docs/state/workspaces.html — jordanm
@jordanm ah, true, I forgot about state. I have it only for us-west-2 now: ``` terraform { backend "s3" { bucket = "test" profile = "test-profile" dynamodb_table = "tf-state-lock-dyndb" region = "us-west-2" key = "test/terraform.tfstate" } } ``` But as far as I tested, I can't use variables in backend configuration. So I just need to create the same state but with another region and it should be fine? — Anton Gorkiy

Anton Gorkiy Anton Gorkiy · Accepted Answer · 2020-09-02T13:32:29

Didn't realized I need different workspaces for different regions to save state, closing.

 app-dev-us = {
  env_name                      = "dev"
  vpc_name                      = "app-vpc-dev"
  vpc_cidr                      = "10.12.0.0/16"
  vpc_azs                       = ["us-west-2a", "us-west-2b"]
  vpc_private_subnets           = ["10.12.60.0/24", "10.12.61.0/24"]
  vpc_public_subnets            = ["10.12.160.0/24", "10.12.161.0/24"]
}
app-dev-eu = {
  env_name                      = "dev"
  vpc_name                      = "app-vpc-dev"
  vpc_cidr                      = "10.13.0.0/16"
  vpc_azs                       = ["eu-central-1a", "eu-central-1b"]
  vpc_private_subnets           = ["10.13.60.0/24", "10.13.61.0/24"]
  vpc_public_subnets            = ["10.13.160.0/24", "10.13.161.0/24"]
}

Terrraform: create aws vpc in different regions based on region input variable

1 Answers