arg-env

Node.js package to work with .env files in the same way as docker and docker-compose via argument --env-file=… in CLI, "env_file": […] in package.json and environment variables ENV_FILE_?=…

Installation

npm install --save-dev arg-env

Usage

In addition, check the example of usage

Command-line arguments

See Node docs

node --require=arg-env index.js --env-file=1.env --env-file=2.env

# jest
node -r arg-env node_modules/.bin/jest --env-file=test.env

package.json

See npm docs

{
  "config": {
    "env_file": [
      "3.env",
      "./4.env"
    ]
  },
  "scripts": {
    "start:dev": "node --require=arg-env index.js"
  }
}

Parser only

import { parse } from "arg-env"

Features

All specifications are taken from output of actual docker run

Syntax

• Comments: COMMENTED=comment #ed is resolved to comment
• Quote agnostic: V1=val,V2='val',V3="val" are resolved to val
• Reuse: EXPR=${VAR1} and ${VAR2} is resolved to value1 and value2
• Default value: DEFAULT=${UNDEFINED:-val} is resolved to val

Closure

Files are independent but rely on global environment

Precedence and overwrite

Files don’t overwrite global environment. Next file takes precedence over previous. In addition, files in package.json has less priority than in command line arguments.

Comparison

Other env JS packages hasn't command-line and package interfaces, more-over, didn't behave like docker: see details ./src/parse.spec.ts. Input is ./src/specs/input.env, output saved in ./src/specs/spec.json via ./src/specs/get.sh.

Tool name	Quotes	Isolated	Inline comment	Reuse	Default value	Weird names	Error syntax	Var of Var
docker-compose	',"	Yes	Yes	Yes	Yes	Yes	No	No
arg-env	',"	Yes	Yes	Yes	Yes	Yes	Not yet	Not yet
dotenv	',"	Yes	No	No	No	No	No	No
dotenv-expand	',"	No?	No	More	No	No	No	No
dotenv-extended	',"	No?	No	No	No	No	No	No
envfile	No	-	No	No	No	Other	No	No

Etc

Experiments with .env stuff

• Setup: ./setup.sh
• Build: ./prebuild.sh
  • Launch commands: ./get_envs.sh
• Result: output.md

Envs list is taken from docker-compose/docker-compose.yml (service injected) and written to docker/.env