Convert HCL Maps and Lists to JSON

Maps and Lists in HCL

HCL has native syntax for maps (key-value collections) and lists (ordered sequences) that map directly to JSON objects and arrays. Understanding this mapping is essential for working with Terraform's JSON syntax.

HCL Map Syntax

locals {
  tags = {
    Environment = "production"
    Team        = "platform"
    Project     = "devtoolbox"
    ManagedBy   = "terraform"
  }
}

Maps use curly braces with key = value syntax. In JSON, these become regular objects:

{
  "locals": {
    "tags": {
      "Environment": "production",
      "Team": "platform",
      "Project": "devtoolbox",
      "ManagedBy": "terraform"
    }
  }
}

HCL List Syntax

variable "availability_zones" {
  default = ["us-east-1a", "us-east-1b", "us-east-1c"]
}

variable "ports" {
  default = [80, 443, 8080]
}

Lists use square brackets with comma-separated values, identical to JSON arrays.

Nested Collections

Maps can contain lists and vice versa:

locals {
  services = {
    web = ["nginx", "apache"]
    db  = ["postgres", "redis"]
  }
}

Map vs Block

A common source of confusion is the difference between map attributes and blocks. Maps use = assignment, while blocks do not. In JSON, both become objects, but their semantic meaning in Terraform differs.