Convert Terraform Locals Block to JSON

Terraform Locals in HCL and JSON

The locals block defines named values within a module that can be referenced throughout the configuration. Unlike variables, locals are computed within the module and not exposed as inputs.

HCL Locals Definition

locals {
  environment = "production"
  project     = "devtoolbox"
  region      = "us-east-1"

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

  name_prefix = "devtoolbox-prod"

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

JSON Structure

The locals block is unique because it has no labels. All attributes are direct children:

{
  "locals": {
    "environment": "production",
    "project": "devtoolbox",
    "region": "us-east-1",
    "common_tags": {
      "Environment": "production",
      "Project": "devtoolbox",
      "ManagedBy": "terraform",
      "Team": "platform"
    },
    "name_prefix": "devtoolbox-prod",
    "availability_zones": [
      "us-east-1a",
      "us-east-1b",
      "us-east-1c"
    ]
  }
}

Expression Locals

Locals often contain computed expressions:

locals {
  subnet_count = 3
  vpc_cidr     = "10.0.0.0/16"
}

Expressions like length(var.availability_zones) or "${var.project}-${var.environment}" become strings in JSON.

Multiple Locals Blocks

HCL allows multiple locals blocks in the same file. In JSON, they merge into a single locals object. The converter handles this by collecting all local values together.

Locals vs Variables

While both define named values, variable blocks accept external input and locals blocks compute values internally. This distinction is preserved in the JSON structure.