Env-o-loader NPM

Env-o-Loader

This is a helper to make easier loading enviroment-oriented settings.

This code was born inside B2WAds code base, and it made sense to release this as open source.

Simply import the module and call it as a function:

const loader = require("env-o-loader")
const settings = loader(require("config/my-app"))

The configuration object must have a defaults key at least, and should have a key for each environment you intent to work with.

Let’s take the following JSON settings file:

{
  "defaults": "some default value",
  "test": "test environment",
  "production": "env:MY_VAR"
}

Env-o-Loader will select the environment according to the NODE_ENV envvar content, defaults to development.

If NODE_ENV is test, Env-o-Loader returns "test environment";
If NODE_ENV is production, Env-o-Loader returns the content of the MY_VAR envvar;
If NODE_ENV is something else, Env-o-Loader returns "some default value".

You also can supply the environment you want as second parameter:

loader(require("./config"), "sandbox")

The object environment advantage is that the defaults value fullfills the undefined keys.

For example:

{
  "defaults": {
    "x": 3,
    "y": 4
  },
  "development": {
    "z": 5
  }
}

Under development environment, Env-o-Loader returns the following object:

{ x: 3, y: 4, z: 5 }

You can use nested keys. For example, the sample above can be written as:

{
  "defaults": {
    "x": 3,
    "y": 4
  },
  "development.z": 5
}

With the same result.

Nested keys can be multilevel:

{
  "defaults": {},
  "development": {
    "foo.bar.a": true,
    "foo.bar.b": false,
    "foo.baaz": null
  }
}

Leading to:

{
  foo: {
    bar: { a: true, b: false },
    baaz: null,
  },
}

And can be compound with unnested one:

{
  "defaults": {},
  "development": {
    "foo": { "baaz": null },
    "foo.bar": { "a": true },
    "foo.bar.b": false
  }
}

Using the env: prefix, Env-o-Loader loads the content from an envvar.

To load objects from envvar, use querystring format:

{
  "defaults": {},
  "production": "env:SETTINGS"
}

env SETTINGS="x=3&y=4&foo[]=bar&foo[]=baaz"

Nested objects can be got like:

env SETTINGS="v[x]=3&v[y]=4"

If you must load settings from JSON or envvar, Env-o-Loader supports more types than those formats, serialised as string.

Date: use ISO 8601: 2010-10-10 for October 10, 2010.
Time: use ISO 8601: 2010-10-10T12:30:00Z for October 10, 2010, 12:30 UTC.
Duration: use ISO 8601: P3Y6M4DT12H30M5S for 3 year, 6 months, four days, 12 hours, 30 minutes, and 5 seconds.
Regular expressions: write the regex inside a string. For example: "/\\w(cde)?/i" means /\w(cde)?/i.

Extras only in querystring: