a configuration language

  • hcl

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Ported from https://github.com/hashicorp/hcl
HCL (HashiCorp Configuration Language) is a configuration language built by HashiCorp. The goal of HCL is to build a structured configuration language that is both human and machine friendly for use with command-line tools, but specifically targeted towards DevOps tools, servers, etc.
HCL is also fully JSON compatible. That is, JSON can be used as completely valid input to a system expecting HCL. This helps makes systems interoperable with other systems.
HCL is heavily inspired by libucl, nginx configuration, and others similar.


  • http://www.terraform.io/docs/configuration/syntax.html
  • https://github.com/hashicorp/hcl/blob/master/hcl/parse.y


The complete grammar can be found here, if you're more comfortable reading specifics, but a high-level overview of the syntax and grammar are listed here.
  • Single line comments start with # or //

  • Multi-line comments are wrapped in / and /

  • Values are assigned with the syntax key = value (whitespace doesn't matter). The value can be any primitive: a string, number, boolean, object, or list.

  • Strings are double-quoted and can contain any UTF-8 characters. Example: "Hello, World"

  • Numbers are assumed to be base 10. If you prefix a number with 0x, it is treated as a hexadecimal. If it is prefixed with 0, it is treated as an octal. Numbers can be in scientific notation: "1e10".

  • Boolean values: true, false, on, off, yes, no.

  • Arrays can be made by wrapping it in . Example: "foo", "bar", 42. Arrays can contain primitives and other arrays, but cannot contain objects. Objects must use the block syntax shown below.

  • Objects and nested objects are created using the structure shown below:

variable "ami" {
    description = "the AMI to use"


The original language is licenced under Mozilla Public License, version 2.0 https://github.com/hashicorp/hcl/blob/master/LICENSE
Whatever that is mine is under MIT.