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Updating my post to ensure `depends_on` is preferred, as the method detailed is a hack when this functionality for modules did not yet exist.
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MrPooh
MrPooh
  • 71
  • 1
  • 4

Update: As of TF 0.13x, depends_on is supported to create dependencies between modules. Using depends_on should be preferable over using the method detailed below.

The previous most popular answer is out of date with Terraform in version 0.12.24.

depends_on is a protected variable, and cannot be used in a module. In addition there are a few syntax differences.

I've updated the example below.

# ROOT level main.tf
# -------------------------------------------------------------------
# Create NAT Gateway - Associates EIP as well
# -------------------------------------------------------------------
module "vpc_nat_gateway" {
  source            = "./vpc_nat_gateway"
  vpc_id            = module.vpc.id
  public_subnet_ids = module.vpc_subnets.public_subnet_ids
  private_cidr      = var.private_cidr
  common_tags       = local.common_tags
}

# -------------------------------------------------------------------
# Create Private Routes
# -------------------------------------------------------------------
module "vpc_private_route" {
  source         = "./vpc_private_route"
  vpc_id.        = module.vpc.id
  nat_gateway_id = module.vpc_nat_gateway.nat_gateway_id
  common_tags    = local.common_tags

  # Depends is a custom variable, depends_on is a reserved keyword.
  depends = [module.vpc_nat_gateway.nat_gateway_id]
}

# vpc_private_route module - main.tf
variable "depends" {
  default = []
}

resource "null_resource" "depends_on" {
  triggers = {
    depends_on = "${join("", var.depends)}"
  }
}

data "aws_nat_gateway" "az1" {
  vpc_id = var.vpc_id

  depends_on = [
    null_resource.depends_on
  ]
}

data "aws_nat_gateway" "az2" {
  vpc_id = var.vpc_id

  depends_on = [
    null_resource.depends_on
  ]
}

The most popular answer is out of date with Terraform in version 0.12.24.

depends_on is a protected variable, and cannot be used in a module. In addition there are a few syntax differences.

I've updated the example below.

# ROOT level main.tf
# -------------------------------------------------------------------
# Create NAT Gateway - Associates EIP as well
# -------------------------------------------------------------------
module "vpc_nat_gateway" {
  source            = "./vpc_nat_gateway"
  vpc_id            = module.vpc.id
  public_subnet_ids = module.vpc_subnets.public_subnet_ids
  private_cidr      = var.private_cidr
  common_tags       = local.common_tags
}

# -------------------------------------------------------------------
# Create Private Routes
# -------------------------------------------------------------------
module "vpc_private_route" {
  source         = "./vpc_private_route"
  vpc_id.        = module.vpc.id
  nat_gateway_id = module.vpc_nat_gateway.nat_gateway_id
  common_tags    = local.common_tags

  # Depends is a custom variable, depends_on is a reserved keyword.
  depends = [module.vpc_nat_gateway.nat_gateway_id]
}

# vpc_private_route module - main.tf
variable "depends" {
  default = []
}

resource "null_resource" "depends_on" {
  triggers = {
    depends_on = "${join("", var.depends)}"
  }
}

data "aws_nat_gateway" "az1" {
  vpc_id = var.vpc_id

  depends_on = [
    null_resource.depends_on
  ]
}

data "aws_nat_gateway" "az2" {
  vpc_id = var.vpc_id

  depends_on = [
    null_resource.depends_on
  ]
}

Update: As of TF 0.13x, depends_on is supported to create dependencies between modules. Using depends_on should be preferable over using the method detailed below.

The previous most popular answer is out of date with Terraform 0.12.24.

depends_on is a protected variable, and cannot be used in a module. In addition there are a few syntax differences.

I've updated the example below.

# ROOT level main.tf
# -------------------------------------------------------------------
# Create NAT Gateway - Associates EIP as well
# -------------------------------------------------------------------
module "vpc_nat_gateway" {
  source            = "./vpc_nat_gateway"
  vpc_id            = module.vpc.id
  public_subnet_ids = module.vpc_subnets.public_subnet_ids
  private_cidr      = var.private_cidr
  common_tags       = local.common_tags
}

# -------------------------------------------------------------------
# Create Private Routes
# -------------------------------------------------------------------
module "vpc_private_route" {
  source         = "./vpc_private_route"
  vpc_id.        = module.vpc.id
  nat_gateway_id = module.vpc_nat_gateway.nat_gateway_id
  common_tags    = local.common_tags

  # Depends is a custom variable, depends_on is a reserved keyword.
  depends = [module.vpc_nat_gateway.nat_gateway_id]
}

# vpc_private_route module - main.tf
variable "depends" {
  default = []
}

resource "null_resource" "depends_on" {
  triggers = {
    depends_on = "${join("", var.depends)}"
  }
}

data "aws_nat_gateway" "az1" {
  vpc_id = var.vpc_id

  depends_on = [
    null_resource.depends_on
  ]
}

data "aws_nat_gateway" "az2" {
  vpc_id = var.vpc_id

  depends_on = [
    null_resource.depends_on
  ]
}
Editing word usage. The version refers to my local version. When this change was introduced as a protected variable, could be sometime earlier.
Source Link
MrPooh
MrPooh
  • 71
  • 1
  • 4

The most popular answer is out of date with Terraform as ofin version 0.12.24.

depends_on is a protected variable, and cannot be used in a module. In addition there are a few syntax differences.

I've updated the example below.

# ROOT level main.tf
# -------------------------------------------------------------------
# Create NAT Gateway - Associates EIP as well
# -------------------------------------------------------------------
module "vpc_nat_gateway" {
  source            = "./vpc_nat_gateway"
  vpc_id            = module.vpc.id
  public_subnet_ids = module.vpc_subnets.public_subnet_ids
  private_cidr      = var.private_cidr
  common_tags       = local.common_tags
}

# -------------------------------------------------------------------
# Create Private Routes
# -------------------------------------------------------------------
module "vpc_private_route" {
  source         = "./vpc_private_route"
  vpc_id.        = module.vpc.id
  nat_gateway_id = module.vpc_nat_gateway.nat_gateway_id
  common_tags    = local.common_tags

  # Depends is a custom variable, depends_on is a reserved keyword.
  depends = [module.vpc_nat_gateway.nat_gateway_id]
}

# vpc_private_route module - main.tf
variable "depends" {
  default = []
}

resource "null_resource" "depends_on" {
  triggers = {
    depends_on = "${join("", var.depends)}"
  }
}

data "aws_nat_gateway" "az1" {
  vpc_id = var.vpc_id

  depends_on = [
    null_resource.depends_on
  ]
}

data "aws_nat_gateway" "az2" {
  vpc_id = var.vpc_id

  depends_on = [
    null_resource.depends_on
  ]
}

The most popular answer is out of date with Terraform as of version 0.12.24.

depends_on is a protected variable, and cannot be used in a module. In addition there are a few syntax differences.

I've updated the example below.

# ROOT level main.tf
# -------------------------------------------------------------------
# Create NAT Gateway - Associates EIP as well
# -------------------------------------------------------------------
module "vpc_nat_gateway" {
  source            = "./vpc_nat_gateway"
  vpc_id            = module.vpc.id
  public_subnet_ids = module.vpc_subnets.public_subnet_ids
  private_cidr      = var.private_cidr
  common_tags       = local.common_tags
}

# -------------------------------------------------------------------
# Create Private Routes
# -------------------------------------------------------------------
module "vpc_private_route" {
  source         = "./vpc_private_route"
  vpc_id.        = module.vpc.id
  nat_gateway_id = module.vpc_nat_gateway.nat_gateway_id
  common_tags    = local.common_tags

  # Depends is a custom variable, depends_on is a reserved keyword.
  depends = [module.vpc_nat_gateway.nat_gateway_id]
}

# vpc_private_route module - main.tf
variable "depends" {
  default = []
}

resource "null_resource" "depends_on" {
  triggers = {
    depends_on = "${join("", var.depends)}"
  }
}

data "aws_nat_gateway" "az1" {
  vpc_id = var.vpc_id

  depends_on = [
    null_resource.depends_on
  ]
}

data "aws_nat_gateway" "az2" {
  vpc_id = var.vpc_id

  depends_on = [
    null_resource.depends_on
  ]
}

The most popular answer is out of date with Terraform in version 0.12.24.

depends_on is a protected variable, and cannot be used in a module. In addition there are a few syntax differences.

I've updated the example below.

# ROOT level main.tf
# -------------------------------------------------------------------
# Create NAT Gateway - Associates EIP as well
# -------------------------------------------------------------------
module "vpc_nat_gateway" {
  source            = "./vpc_nat_gateway"
  vpc_id            = module.vpc.id
  public_subnet_ids = module.vpc_subnets.public_subnet_ids
  private_cidr      = var.private_cidr
  common_tags       = local.common_tags
}

# -------------------------------------------------------------------
# Create Private Routes
# -------------------------------------------------------------------
module "vpc_private_route" {
  source         = "./vpc_private_route"
  vpc_id.        = module.vpc.id
  nat_gateway_id = module.vpc_nat_gateway.nat_gateway_id
  common_tags    = local.common_tags

  # Depends is a custom variable, depends_on is a reserved keyword.
  depends = [module.vpc_nat_gateway.nat_gateway_id]
}

# vpc_private_route module - main.tf
variable "depends" {
  default = []
}

resource "null_resource" "depends_on" {
  triggers = {
    depends_on = "${join("", var.depends)}"
  }
}

data "aws_nat_gateway" "az1" {
  vpc_id = var.vpc_id

  depends_on = [
    null_resource.depends_on
  ]
}

data "aws_nat_gateway" "az2" {
  vpc_id = var.vpc_id

  depends_on = [
    null_resource.depends_on
  ]
}
Source Link
MrPooh
MrPooh
  • 71
  • 1
  • 4

The most popular answer is out of date with Terraform as of version 0.12.24.

depends_on is a protected variable, and cannot be used in a module. In addition there are a few syntax differences.

I've updated the example below.

# ROOT level main.tf
# -------------------------------------------------------------------
# Create NAT Gateway - Associates EIP as well
# -------------------------------------------------------------------
module "vpc_nat_gateway" {
  source            = "./vpc_nat_gateway"
  vpc_id            = module.vpc.id
  public_subnet_ids = module.vpc_subnets.public_subnet_ids
  private_cidr      = var.private_cidr
  common_tags       = local.common_tags
}

# -------------------------------------------------------------------
# Create Private Routes
# -------------------------------------------------------------------
module "vpc_private_route" {
  source         = "./vpc_private_route"
  vpc_id.        = module.vpc.id
  nat_gateway_id = module.vpc_nat_gateway.nat_gateway_id
  common_tags    = local.common_tags

  # Depends is a custom variable, depends_on is a reserved keyword.
  depends = [module.vpc_nat_gateway.nat_gateway_id]
}

# vpc_private_route module - main.tf
variable "depends" {
  default = []
}

resource "null_resource" "depends_on" {
  triggers = {
    depends_on = "${join("", var.depends)}"
  }
}

data "aws_nat_gateway" "az1" {
  vpc_id = var.vpc_id

  depends_on = [
    null_resource.depends_on
  ]
}

data "aws_nat_gateway" "az2" {
  vpc_id = var.vpc_id

  depends_on = [
    null_resource.depends_on
  ]
}