@danmasta/interpolate

Interpolate

Simple template string interpolation for strings and files

Features:

• Easy to use
• Interpolate template strings: {{VAR}}
• Parses strings and files
• Can interpolate from parameters and/or environment variables
• Supports nested paths from complex parameters
• Includes cli tool and node api

About

We needed a way to interpolate template variables from strings and files at build and/or run time. I wanted both a node api and cli tool to use for easy integration with jenkins, docker, or kubernetes, and also wanted the ability to interpolate with environment variables or manually specified parameters.

Usage

Add interpolate as a dependency for your app and install via npm

npm install @danmasta/interpolate --save

Require the package in your app

const interpolate = require('@danmasta/interpolate');

Options

name	alias	type	description
input	i	string	Directory or file path to use when reading files
output	o	string	Directory to write parsed files to
src		string	Glob pattern string to filter input file list, ex: **/*.yml
string	s	string	Text string to parse
env	e	boolean	If true will also interpolate with environment variables. Default is false
params	p	object|string	Object of key,value pairs to use for parameter matching. If string, it should either be a stringified json object, or a comma-separated key,value list: "key1=1,key2=2". Default is null
warn	w	boolean	If true will write a message to stderr when a parameter is not found. Default is true
throw	t	boolean	If true will throw an error when a parameter is not found. Default is false
default	d	string	Default value to use when a parameter is not found. Default is ''
help	h	boolean	View the cli help menu

Methods

Name	Description
Interpolator(opts)	Interpolator class for creating a custom parser instance
parse(str, opts)	Parses a string with optional opts
file({ input, output, src })	Parses a file or directory based in opts.input. Files are parsed then written to opts.output

Examples

Parse a text string

let params = {
    SRC_DIR: './src',
    BUILD_DIR: './build'
};

let string = '{{SRC_DIR}} -> {{BUILD_DIR}}';

console.log(interpolator.parse(str, { params }));

Parse a directory of files via cli

interpolate --env -i ./deploy -o ./build --src **/*.(yml|yaml)

Testing

Testing is currently run using mocha and chai. To execute tests just run npm run test. To generate unit test coverage reports just run npm run coverage

Contact

If you have any questions feel free to get in touch