hexedpackets/hxl

An Elixir implementation of HCL.

HXL

---

An Elixir implementation of HCL

Features

• Decode from string or file
• Aims to be fully compliant with the HCL specification
• Function & variables support during evaluation

Example Usage

hcl = """
resource "upcloud_server" "server1" {
  hostname = "terraform.example.com"

  zone = "nl-ams1"

  plan = "1xCPU-1GB"

  template {
    size = 25
    storage = "01000000-0000-4000-8000-000030200200"
  }

  network_interface {
    type = "public"
  }

  login {
    user = "root"
    keys = [
      "ssh-rsa public key",
    ]
    create_password = true
    password_delivery = "email"
  }

  connection {
    host        = "127.0.0.2"
    type        = "ssh"
    user        = "root"
    private_key = file("~/.ssh/rsa_private_key")
  }

  provisioner "remote-exec" {
    inline = [
      "echo 'Hello world!'"
    ]
  }
}
"""

{:ok, config_file} = HXL.decode(hcl, functions: %{"file" => &File.read/1})

From file

{:ok, config_file} = HXL.decode_file("/path/to/file")

As ast

hcl = """
service "http" {
  a = 1
  b = 2
}
"""

{:ok %HXL.Body{}} = HXL.decode_as_ast(hcl)

Installation

Add hxl to your list of dependencies in mix.exs:

def deps do
  [
    {:hxl, "~> 0.1.0"}
  ]
end

HCL Syntax Specification

Lexical Elements

• Comments
• Identifiers
• Operators & delimiters
• Numeric literals

Structural Language

• Body
• Attributes
• Blocks
• One-line blocks

Expression language

• Expressions
  • Expr term
    • Literal Value
    • Collection Value
    • Template Expr
    • Variable Expr
    • Function Call
    • For Expr
    • ExprTerm Index
    • ExprTerm GetAttr
    • ExprTerm Splat
    • "(" Expression ")"
  • Operation
  • Conditional

Template Language

• [] TemplateLiteral
• [] TemplateInterpolation
• [] TemplateDirective

Representations

• HCL Native syntax
• JSON