template2env

A micro dependency that interpolates environment variables

Description

template2env is a single function that accepts a string (and an optional object of options) as a parameter and returns an interpolated string with varaibles replaced by matching environment variables (located in process.env).

It will throw if a matching variable is not found in process.env and will return the string that was passed if nothing was found to interpolate.

Use case

Imagine a projects configuration is stored in JSON or YAML and you want one configuration file for all your environments.

# config.yaml
site: my site
host: ${HOST}
port: ${PORT}

If process.env contains HOST and PORT template2env will intrpolate the yaml and return the matching values, so your local development environment could look like

# local dev environment
# export HOST="localhost"
# export PORT=8888
site: my site
host: localhost
port: 8888

But your production environment could look like

# production environment
# export HOST="foo.biz"
# export PORT=3001
site: my site
host: foo.biz
port: 3001

How to use

var template2env = require('template2env'),
  fs = require('fs');

fs.readFile('config.yaml', function (err, data) {
  if (err) throw err;
  console.log(template2env(data));
});

Options

template2env accepts an object of options as an optional second paramter start {string} ('${') - start token for interpolation end {string} ('}') - end token

Example

/* if config.yaml uses `{{VARIABLE}}` for interpolation */

var template2env = require('template2env'),
  fs = require('fs');

fs.readFile('config.yaml', function (err, data) {
  if (err) throw err;
  console.log(template2env(data, { start: '{{', end: '}}' }));
});