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. Default is undefined
output	o	string	Directory to write parsed files to. Default is undefined
src		string	Glob pattern string to filter input file list, ex: **/*.yml. Default is undefined
string	s	string	Text string to parse. Default is undefined
stdin		boolean	Read input from stdin. Default is false
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 undefined
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
parse(str, opts)	Parses a string with optional opts
file({ input, output, src })	Parses a file or directory based on opts.input. Files are parsed then written to opts.output

Envstr

This package includes an extra cli utility called envstr. It formats json or table style data into key=val pairs that can be easily consumed in bash scripts or exported as environment variables.

Options

name	alias	type	description
string	s	string	Text string to parse. Default is undefined
stdin		boolean	Read input from stdin. Default is undefined
json	j	boolean	Handle input as json. Default is false
key	k	string	If input is json, parse data at specified key. Default is undefined
quotes	q	boolean	If true add quotes around env values. Default is false
newline	n	string	Which character to use as newline delimeter. Default is '\n'
include	i	string	Which keys to include in output: key1,key2
exclude	e	string	Which keys to exclude from output: key3,key4
help	h	boolean	View the cli help menu

Examples

Parse a text string

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

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

console.log(interpolate(str, { params }));

Parse a directory of files via cli

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

Convert json data to env str format

envstr -s '{"KEY1":true,"KEY2":false}' --json --quotes

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