Extendable configuration base class for 12 Factor application.
npm install @scaleleap/config
> Extendable configuration base class for 12 Factor application.
``sh`
npm i @scaleleap/config
`ts
// in ./src/config.ts
import { BaseConfig } from '@scaleleap/config'
class Config extends BaseConfig {
public readonly TEST = this.get('TEST').asString()
}
`
`ts
// in ./src/app.ts
const config = new Config()
console.log(config.TEST)
`
Parent Config class exposes a single protected method get, which maps to
env-var#get method.
The constructor accepts a single argument, which is an dictionary of key-value strings, that
represents the environment. The value defaults to
process.env.
This is useful, when you'd like to override the values for testing:
`ts`
const config = new Config({ NODE_ENV: '...' })
This module will automatically read .env file contents from $PWD/.env.
You can influence the discovery path of .env file via DOTENV_CONFIG_PATH environment variable.
E.g.
`sh`
DOTENV_CONFIG_PATH=.env.prod node foo.js
Sometimes it is desirable to scope all of the environment variables. This can be achieved through
a prefix.
Example:
`ts
class Config extends BaseConfig {
protected readonly prefix = 'FOO_'
public readonly TEST = this.get('TEST').asString()
}
`
Will then look for environment variable named FOO_TEST instead of just TEST.
Note: The underscore _ character is not included by default and must be part of your prefix.
Be careful when working with built-in variables, as they would not be discovered, because of the prefix.
It is possible to expand variables:
`sh`
FOO=bar
BAZ=${FOO}-baz
When the BAZ value is expanded, the result will be:
`sh`
FOO=bar
BAZ=bar-baz
There are some universal variables that are included into the config.
For now, there is just one.
#### NODE_ENV
Valid values are:
* development
*
*
Example:
`sh`
NODE_ENV=production node foo.js
Also comes with convenience boolean assertion getters:
* isDevelopment
*
*
Example:
`ts
const config = new Config()
if (config.isDevelopment) {
// do something destructive
}
`
* Property names should match the environment variable name, including case. E.g. NODE_ENV.readonly
* Properties should be always marked as .asBoolStrict
* Use strict methods where possible, e.g. use not asBool`.
MIT © Scale Leap
