terrascript-plugin-template-expressions

Terrascript plugin which implements template expressions functionality. Template expressions allow for more dynamic configurations in a terrascript.yml by allowing the referencing of various available variables within the current context or even to run arbitrary JavaScript code.

Install

This plugin comes with any installation of Terrascript as a dependency.

Usage

The main available variable is called context whose main fields look like:

interface Context {
  conf: IConfig;
  spec: ISpec;
  cmd: string;
  args: string[];
  target?: ITarget; // available in target hooks, action hooks, and actions
}

conf is the current config under which the given command/hook/script is being run.

spec is the yaml configuration (or specification) under which the given command/hook/script is being run.

cmd and args are the command and arguments from the CLI input.

target is the current target.

Also, for convenience, conf, spec, and target are made directly available in templates.

Template expressions are evaluated dynamically at runtime and can access inherited values from parent projects.

name: project
target:
  dev:
scripts:
  things:
    - echo {{ spec.name }}
    - echo {{ target.name }}
    - echo {{ 1 + 1 }}

terrascript dev things
# project
# dev
# 2