HCL language preview

1. Resource block

resource blocks and "${...}" interpolation

horizon-dark

# Web server
resource "aws_instance" "web" {
  ami           = var.ami_id
  instance_type = "t3.micro"
  count         = 2

  tags = {
    Name = "web-${count.index}"
    Env  = var.environment
  }
}

atom-one-dark

# Web server
resource "aws_instance" "web" {
  ami           = var.ami_id
  instance_type = "t3.micro"
  count         = 2

  tags = {
    Name = "web-${count.index}"
    Env  = var.environment
  }
}

github-dark

# Web server
resource "aws_instance" "web" {
  ami           = var.ami_id
  instance_type = "t3.micro"
  count         = 2

  tags = {
    Name = "web-${count.index}"
    Env  = var.environment
  }
}

dracula

# Web server
resource "aws_instance" "web" {
  ami           = var.ami_id
  instance_type = "t3.micro"
  count         = 2

  tags = {
    Name = "web-${count.index}"
    Env  = var.environment
  }
}

nord

# Web server
resource "aws_instance" "web" {
  ami           = var.ami_id
  instance_type = "t3.micro"
  count         = 2

  tags = {
    Name = "web-${count.index}"
    Env  = var.environment
  }
}

github

# Web server
resource "aws_instance" "web" {
  ami           = var.ami_id
  instance_type = "t3.micro"
  count         = 2

  tags = {
    Name = "web-${count.index}"
    Env  = var.environment
  }
}

2. Terraform settings

terraform, variable, output, and locals blocks

horizon-dark

terraform {
  required_version = ">= 1.6.0"

  required_providers {
    aws = {
      source  = "hashicorp/aws"
      version = "~> 5.0"
    }
  }
}

variable "environment" {
  type    = string
  default = "dev"
}

locals {
  is_prod = var.environment == "prod"
}

output "instance_ids" {
  value = aws_instance.web[*].id
}

atom-one-dark

terraform {
  required_version = ">= 1.6.0"

  required_providers {
    aws = {
      source  = "hashicorp/aws"
      version = "~> 5.0"
    }
  }
}

variable "environment" {
  type    = string
  default = "dev"
}

locals {
  is_prod = var.environment == "prod"
}

output "instance_ids" {
  value = aws_instance.web[*].id
}

github-dark

terraform {
  required_version = ">= 1.6.0"

  required_providers {
    aws = {
      source  = "hashicorp/aws"
      version = "~> 5.0"
    }
  }
}

variable "environment" {
  type    = string
  default = "dev"
}

locals {
  is_prod = var.environment == "prod"
}

output "instance_ids" {
  value = aws_instance.web[*].id
}

dracula

terraform {
  required_version = ">= 1.6.0"

  required_providers {
    aws = {
      source  = "hashicorp/aws"
      version = "~> 5.0"
    }
  }
}

variable "environment" {
  type    = string
  default = "dev"
}

locals {
  is_prod = var.environment == "prod"
}

output "instance_ids" {
  value = aws_instance.web[*].id
}

nord

terraform {
  required_version = ">= 1.6.0"

  required_providers {
    aws = {
      source  = "hashicorp/aws"
      version = "~> 5.0"
    }
  }
}

variable "environment" {
  type    = string
  default = "dev"
}

locals {
  is_prod = var.environment == "prod"
}

output "instance_ids" {
  value = aws_instance.web[*].id
}

github

terraform {
  required_version = ">= 1.6.0"

  required_providers {
    aws = {
      source  = "hashicorp/aws"
      version = "~> 5.0"
    }
  }
}

variable "environment" {
  type    = string
  default = "dev"
}

locals {
  is_prod = var.environment == "prod"
}

output "instance_ids" {
  value = aws_instance.web[*].id
}

3. Heredoc and dynamic blocks

<<- heredoc and dynamic ingress

horizon-dark

resource "aws_iam_policy" "this" {
  name = "example"

  policy = <<-EOT
    {
      "Version": "2012-10-17",
      "Statement": []
    }
  EOT
}

resource "aws_security_group" "this" {
  dynamic "ingress" {
    for_each = var.ports
    content {
      from_port = ingress.value
      to_port   = ingress.value
      protocol  = "tcp"
    }
  }
}

atom-one-dark

resource "aws_iam_policy" "this" {
  name = "example"

  policy = <<-EOT
    {
      "Version": "2012-10-17",
      "Statement": []
    }
  EOT
}

resource "aws_security_group" "this" {
  dynamic "ingress" {
    for_each = var.ports
    content {
      from_port = ingress.value
      to_port   = ingress.value
      protocol  = "tcp"
    }
  }
}

github-dark

resource "aws_iam_policy" "this" {
  name = "example"

  policy = <<-EOT
    {
      "Version": "2012-10-17",
      "Statement": []
    }
  EOT
}

resource "aws_security_group" "this" {
  dynamic "ingress" {
    for_each = var.ports
    content {
      from_port = ingress.value
      to_port   = ingress.value
      protocol  = "tcp"
    }
  }
}

dracula

resource "aws_iam_policy" "this" {
  name = "example"

  policy = <<-EOT
    {
      "Version": "2012-10-17",
      "Statement": []
    }
  EOT
}

resource "aws_security_group" "this" {
  dynamic "ingress" {
    for_each = var.ports
    content {
      from_port = ingress.value
      to_port   = ingress.value
      protocol  = "tcp"
    }
  }
}

nord

resource "aws_iam_policy" "this" {
  name = "example"

  policy = <<-EOT
    {
      "Version": "2012-10-17",
      "Statement": []
    }
  EOT
}

resource "aws_security_group" "this" {
  dynamic "ingress" {
    for_each = var.ports
    content {
      from_port = ingress.value
      to_port   = ingress.value
      protocol  = "tcp"
    }
  }
}

github

resource "aws_iam_policy" "this" {
  name = "example"

  policy = <<-EOT
    {
      "Version": "2012-10-17",
      "Statement": []
    }
  EOT
}

resource "aws_security_group" "this" {
  dynamic "ingress" {
    for_each = var.ports
    content {
      from_port = ingress.value
      to_port   = ingress.value
      protocol  = "tcp"
    }
  }
}

4. Heredoc with bare words in the body

a bare word line (e.g. true) no longer closes the heredoc early

horizon-dark

resource "aws_instance" "web" {
  user_data = <<EOT
#!/bin/bash
ENABLE_LOGGING=true
if $ENABLE_LOGGING; then
  echo "logging enabled"
fi
true
still inside the heredoc
EOT
}

atom-one-dark

resource "aws_instance" "web" {
  user_data = <<EOT
#!/bin/bash
ENABLE_LOGGING=true
if $ENABLE_LOGGING; then
  echo "logging enabled"
fi
true
still inside the heredoc
EOT
}

github-dark

resource "aws_instance" "web" {
  user_data = <<EOT
#!/bin/bash
ENABLE_LOGGING=true
if $ENABLE_LOGGING; then
  echo "logging enabled"
fi
true
still inside the heredoc
EOT
}

dracula

resource "aws_instance" "web" {
  user_data = <<EOT
#!/bin/bash
ENABLE_LOGGING=true
if $ENABLE_LOGGING; then
  echo "logging enabled"
fi
true
still inside the heredoc
EOT
}

nord

resource "aws_instance" "web" {
  user_data = <<EOT
#!/bin/bash
ENABLE_LOGGING=true
if $ENABLE_LOGGING; then
  echo "logging enabled"
fi
true
still inside the heredoc
EOT
}

github

resource "aws_instance" "web" {
  user_data = <<EOT
#!/bin/bash
ENABLE_LOGGING=true
if $ENABLE_LOGGING; then
  echo "logging enabled"
fi
true
still inside the heredoc
EOT
}

5. Nested interpolation

${...} expressions containing their own {} literals

horizon-dark

locals {
  payload = jsonencode({
    name = var.name
    tags = { env = "${var.environment}" }
  })
}

output "encoded" {
  value = "prefix-${jsonencode({ a = 1 })}"
}

atom-one-dark

locals {
  payload = jsonencode({
    name = var.name
    tags = { env = "${var.environment}" }
  })
}

output "encoded" {
  value = "prefix-${jsonencode({ a = 1 })}"
}

github-dark

locals {
  payload = jsonencode({
    name = var.name
    tags = { env = "${var.environment}" }
  })
}

output "encoded" {
  value = "prefix-${jsonencode({ a = 1 })}"
}

dracula

locals {
  payload = jsonencode({
    name = var.name
    tags = { env = "${var.environment}" }
  })
}

output "encoded" {
  value = "prefix-${jsonencode({ a = 1 })}"
}

nord

locals {
  payload = jsonencode({
    name = var.name
    tags = { env = "${var.environment}" }
  })
}

output "encoded" {
  value = "prefix-${jsonencode({ a = 1 })}"
}

github

locals {
  payload = jsonencode({
    name = var.name
    tags = { env = "${var.environment}" }
  })
}

output "encoded" {
  value = "prefix-${jsonencode({ a = 1 })}"
}