@fnando/env_vars
Access environment variables. Also includes presence validation, type coercion and default values.
Installation
yarn add -E @fnando/env_vars
Usage
// config.js
import {env, int, bool, string} from "@fnando/env_vars"
const config = env(({mandatory, optional}) => {
mandatory("DATABASE_URL", string);
optional("TIMEOUT", int, 10);
optional("FORCE_SSL", bool, false);
optional("NODE_ENV", string, "development", {aliases: ["env"]});
});
export default config;
// app.js
import config from "./config";
config.databaseURL
config.timeout
config.forceSSL
You can also set arbitrary properties, like the following:
// config.js
import {env, string} from "@fnando/env_vars"
import redis from "redis"
const config = env(({property, optional}) => {
optional("REDIS_URL", string, "redis://127.0.0.1");
property("redis", () => redis.createClient(config.redisURL));
});
// app.js
import config from "./config";
import {print} from "redis";
config.redis.set("key", "value", print);
config.redis.get("key", print);
//=> "value"
Missing properties & assignment
An exception is thrown for properties that weren't registered:
config.missing
//=> throws `"missing" is not a registered configuration.`
You're also not allowed to assign properties to the config object.
config.name = "John";
//=> throws `Configuration is read-only ("name" was assigned).`
Acronyms
@fnando/env_vars
supports a small list of acronyms (words that will be set as uppercased in property names). Words like URL
and SSL
will be returned as it is (e.g. REDIS_URL
will be defined as config.redisURL
). The full list is available at https://github.com/fnando/env_vars-node/blob/master/acronyms.js. You can add new words to the list by loading @fnando/env_vars/acronyms
like the following:
import {env, string} from "@fnando/env_vars"
import {acronyms} from "@fnando/env_vars/acronyms";
acronyms.push("RTSP");
const config = env(({optional}) => {
optional("RTSP_SERVER", string, "rtsp://127.0.0.1");
});
config.RTSPServer
Types
You can coerce values to the following types:
-
string
: Is the default. E.g.optional("name", string)
. -
int
: E.g.optional("timeout", int)
. -
float
: E.g.optional("wait", float)
. -
bool
: E.g.optional("force_ssl", bool)
. Any ofyes
,true
or1
is considered astrue
. Any other value will be coerced tofalse
. -
array
: E.g.optional("chars", array())
oroptional("numbers", array(int))
. The environment variable must be something likea,b,c
.
Testing
To stub properties in tests, you can import stub
and restore
:
import {env, int} from "@fnando/env_vars";
import {stub, restore} from "@fnando/env_vars/testing";
const config = env(({optional}) => optional("NUMBER", int, 1234));
config.number
//=> 1234
stub(config, "number", 4321);
config.number
//=> 4321
restore();
config.number
//=> 1234
Development
Run yarn test
to run the tests.
Contributing
Bug reports and pull requests are welcome on GitHub at https://github.com/fnando/env_vars-node. This project is intended to be a safe, welcoming space for collaboration, and contributors are expected to adhere to the Contributor Covenant code of conduct.
License
The package is available as open source under the terms of the MIT License.