Environment Variables

Node에서 환경변수를 설정해보자.

About

This post shows how to inject environment variables to your Node application.

Injecting Environment Variables

Inject within commands

$ NODE_ENV=dev npm start

Just put the environment variable in key=value format at the beginning.

Injecting multiple variables

$ KINESIS_STREAM_NAME=litsynp-stream-dev AWS_REGION=ap-northeast-2 npm start

Inject in package.json

Same as above; but put it in the scripts section of package.json.

// ...
"scripts" : {
  "start": "node index.js",
  "test": "NODE_ENV=test mocha --reporter spec"
}
// ...

Reading Environment Variables

const KINESIS_STREAM_NAME = process.env.KINESIS_STREAM_NAME

This is how you read it. just reference process.env.ENV_NAME to read a specific variable.

The way I prefer is like creating a config file.

src/config.js

export const KINESIS_STREAM_NAME = process.env.KINESIS_STREAM_NAME ?? 'test-stream-name'

• export - Export the variable to be used in other JS files. (This is ESM syntax. CJS, AMD, UMD, ESM)

• ?? - 'Nullish coalescing operator'. Returns right-hand side operand when left-hand side operand is null or undefined. I add right-hand side operand as the fallback value in case the environment variable is not provided.

import { KINESIS_STREAM_NAME } = './config'

• Import the variable from the config file and use it!

Credits

• https://stackoverflow.com/questions/25112510/how-to-set-environment-variables-from-within-package-json