Passing environment variables in npm-scripts
node.jsShellNpmEnvironment Variablesnode.js Problem Overview
I have a package.json with following (simplified) content in the scripts key:
...
scripts: {
"start": "NODE_ENV=${NODE_ENV:=production} node start-app.js",
"poststart": "echo $NODE_ENV"
}
...
From the command line I can run:
npm start
This will run my start-app.js script and set the process.env.NODE_ENV environment variable to "production". See here for syntax explanation.
The poststart will automatically run after start as described [here][2].
However poststart will not "inherit" the NODE_ENV shell environment variable, so the echo command will not echo anything.
My producation code is a little more complex, but what I am trying to accomplish is passing down the NODE_ENV variable from the "starting point" to dependent scripts. Any suggestions/best practices on how to do that?
I dont want to hardcode the NODE_ENV in the poststart, because I might want to do:
NODE_ENV=development npm start
and I want everyting "down the chain" inherit the same environment.
[2]: https://docs.npmjs.com/misc/scripts "here"
node.js Solutions
Solution 1 - node.js
You have a few options:
- better-npm-run,which can define an
env
for each command separately - Instead of a
poststart
script, you can concatenate commands for npm like so:"start": "NODE_ENV=${NODE_ENV:=production} node start-app.js && echo $NODE_ENV"
- Use a process manager in production like pm2. pm2 lets you define environment specific json files with settings such as
NODE_ENV
. At our company, we successfully run all of our apps in different environments with pm2 (all the while having the same start command)
Solution 2 - node.js
this is how I did it, first you need to install two dev-dependencies
https://www.npmjs.com/package/env-cmd this load your env var from your file
https://www.npmjs.com/package/cross-env this use environment variable in script
example scripts:
"env-cmd ./.config/prod.env cross-env-shell \"docker volume create $DOCKER_VOLUME\""
this load $DOCKER_VOLUME env var from prod.env
update: starting from env-cmd version 10, you need specify -f flag if you want to use a custom env file path
"env-cmd -f ./.config/prod.env cross-env-shell \"docker volume create $DOCKER_VOLUME\""
Solution 3 - node.js
If you have small use cased, use better-npm-run. For small cases, it works fine. Somehow if you have a lot of commands and it hard manage. Try, batman-cli. Work well and handle lot of environment-dependent issues
npm i -g batman-cli