Goes as high as environment (including npm config) and as low as command line options to find variable you've requested.
MIT License
Library to read environment variables, including npm package config, custom config file, command line and default object.
$ yarn add envar
$ npm install --save envar
Add some environment variables
$ export user=my_account
$ export pass=my_secret
Run node script with custom port
$ node ./my_project.js --port 8080
Enjoy aggregated state:
var http = require('http')
, envar = require('envar') // it will automatically process command line options (using optimist)
;
// define defaults for demo/test environments
envar.defaults(
{
port: 1337,
user: 'demo',
pass: 'demo'
});
http.createServer(function(req, res)
{
var auth = getAuth(req); // just for the example's sake
if (auth.user == envar('user') && auth.pass == envar('pass'))
{
res.end('Welcome '+envar('user')+'!'); // will be `my_account` or `demo` if environment is not populated
}
else
{
res.end('Please authorize.');
}
}).listen(envar('port')); // will be 8080 or 1337 if no option provided
Adds default parameters to the mix, will be used if all other layers failed lookup. And will be overridden if present in any other layer. Consider it as last resort fallback.
var envar = require('envar');
envar.defaults(
{
port: 1337,
user: 'test'
});
envar('port'); // -> 1337
envar('user'); // -> 'test'
envar('pass'); // -> undefined, not present in any layer
Prefix only affects environment variables layer
$ export my_app_user=me
$ export my_app_pass=12345
$ node ./my_project.js --port 8001
var envar = require('envar');
envar.prefix('my_app_');
envar('user'); // -> me
envar('pass'); // -> 12345
envar('port'); // -> 8001
Default lookup order is AENCD
, where:
A
- argv/cli optionsE
- environment variablesN
- npm package configuration parametersC
- imported json config file (if any)D
- default parametersOrder can be changed by calling envar.order(<new order>);
$ export port=8080
$ node ./my_project.js --port 80
var envar = require('envar');
envar.defaults({port: 1337});
// default order 1. argv, 2. env, 3. npm, 4. json config file, 5. defaults
envar.order(); // -> AENCD
envar('port'); // -> 80
// Change order to 1. env, 2. defaults, 3. argv
envar.order('EDA'); // and don't bother with npm config or json config file
envar('port'); // -> 8080
// Change order to only defaults
envar.order('D');
envar('port'); // -> 1337
// and change it back to original
envar.order('AENCD');
For more information about NPM configuration parameters check out NPM Per-Package Config Settings
$ npm config set my_project:port 80
$ node ./my_project.js
var envar = require('envar');
envar('port'); // -> 80
If you have data stored in some json file, like for example env.json
, you can add it to the mix using envar.import()
method.
Note: envar.import
method is sync like require
, so it makes sense to use it before execution app's logic.
$ cat env.json
{
"port": 5432,
"user": "pg"
}
$ node ./my_project.js
var envar = require('envar');
envar.import('env.json');
envar('port'); // -> 5432
envar('user'); // -> pg
Or if your project is using more sophisticated means of configuration storage, you can pass javascript object.
var envar = require('envar');
storage.getConfig(function(err, config)
{
if (err) throw err;
// config -> {port: 5432, user: 'pg'}
envar.import(config);
envar('port'); // -> 5432
envar('user'); // -> pg
});
In case cases you may need to have access to specific layer in the mix, following methods could be used for this task:
var envar = require('envar');
envar.default('port'); // will fetch data directly from `defaults` layer
envar.config('port'); // will fetch data directly from `config file` layer
envar.npm('port'); // will fetch data directly from `npm package config` layer
envar.env('port'); // will fetch data directly from `environment variables` layer
envar.arg('port'); // will fetch data directly from `argv/cli` layer
Note: All direct layer access methods, can be used to override/assign values.
Note 2: envar.arg
and envar.npm
coerce all values into strings, because of the way node interacts with the process's environment.
var envar = require('envar');
envar.env('test'); // -> undefined
envar.env('test', 25); // -> '25'
envar.env('test'); // -> '25'
process.env['test']; // -> '25'
Note 3: undefined
has special meaning within envar.arg
and envar.npm
, it removes corresponding key from the environment variables, to prevent it coercing into a string (i.e. undefined -> 'undefined'
).
var envar = require('envar');
envar('test'); // -> undefined
envar.env('test', 'me env'); // -> 'me env'
envar.default('test', 'me default'); // -> 'me default'
envar('test'); // -> 'me env'
envar.env('test', undefined); // -> undefined
envar('test'); // -> 'me default'
envar.default('test', undefined); // -> undefined
envar('test'); // -> undefined
History of the project could be found in CHANGELOG.md.
EnVar is licensed under the MIT license.