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Managing .env variables for provisional builds with Create React App

Donghyuk (Jacob) Jang on April 07, 2019

When developing web applications by using Create React App, developers get NODE_ENV=development on their local environment and NODE_ENV=production ...

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Ario Setiawan • Dec 3 '19

How to run it?

i make env.local

it contains

CUSTOM_NODE_ENV="local"
REACT_APP_MAIN_SERVER_API=http://192.168.1.11/api/v1/

this run script in npm

"start:local": "env-cmd -f .env.local react-script start"

when i run

npm start local

it fails and load to .env

Donghyuk (Jacob) Jang • Dec 3 '19 • Edited

@consciousnessdev Thanks for your comment.

You should add REACT_APP_ prefix to your all custom env variables. eg, REACT_APP_CUSTOM_NODE_ENV.

the command is npm run start:local according to your scripts, just missing :.

Sorry for making this mistake, and I will update the article.

Again, thanks for your patient.

Best,
Donghyuk (Jacob) Jang

Ario Setiawan • Dec 4 '19

[Update] But when i run it with your suggestion, it still have an error

npm run start:local

> apps@0.1.0 start:local /home/me/react/apps
> env-cmd -f .env.local react-script start

spawn react-script ENOENT
Hangup
npm ERR! code ELIFECYCLE
npm ERR! errno 129
npm ERR! apps@0.1.0 start:local: `env-cmd -f .env.local react-script start`
npm ERR! Exit status 129
npm ERR! 
npm ERR! Failed at the apps@0.1.0 start:local script.
npm ERR! This is probably not a problem with npm. There is likely additional logging output above.

npm ERR! A complete log of this run can be found in:
npm ERR!     /home/me/.npm/_logs/2019-12-04T01_34_08_907Z-debug.log

Donghyuk (Jacob) Jang • Dec 4 '19

I have tried in the example repository, and it seems to be working fine. You may have some conflicts.

The example repository is github.com/DonghyukJacobJang/cra-e...

You will be able to find .env.local and start:local in package.json.

Since I cannot see all your config and settings, providing you the example repo is the best thing I can do at the moment.

Please let me know if you have questions.

Best,
Donghyuk (Jacob) Jang

Ario Setiawan • Dec 5 '19

Pardon Me, i'd typo on 'react-script', which is true 'react-scripts', with 's' in the end of script it, thanks a lot! :O

j6000 • Oct 31 '19

Thanks Donghyuk. One thing to note here is that, while my .env.staging is loaded, process.env.NODE_ENV is set to production despite the NODE_ENV=staging setting in .env.staging

Is this consistent with your experience?

j6000 • Oct 31 '19 • Edited

Seems so based on create-react-app.dev/docs:

Variables in .env.production will be used as fallback because NODE_ENV will always be set to production for a build.

Assuming true, what's the value in adding NODE_ENV=staging to .env.staging?

Donghyuk (Jacob) Jang • Oct 31 '19

I will test this out ASAP, but I remember that I had to create a custom var to distinguish environments in javascript code.

herberthsu • Oct 17 '19

Nice post, Jacob! thanks!

Larry D Almeida • Sep 15 '19

It's a great post! Thank you. I needed this.

Donghyuk (Jacob) Jang • Sep 15 '19

I am very glad that it helps you :) Thank you so much for your message.

Сергей Данилов • Jan 1 '20

I think, env-cmd should be installed by
$ yarn add -D env-cmd

niki • Jul 28 '20

Thank you for the article!

I was initially confused as I was not aware that "start" and "build" scripts use ".env.development" and ".env.production", respectively, by default.

sushantraje2000 • Jun 9 '19 • Edited

I am using visual studio 2017 with React template
in which I followed above steps but its not working for staging

can you add working source code also

Donghyuk (Jacob) Jang • Jun 10 '19 • Edited

There was env-cmd version update and it required a parameter to point a custom env file, As @foxbit19 discovered.
CRA template with env-cmd example is available at github.com/DonghyukJacobJang/cra-e... .
Thank you so much @sushantraje2000

foxbit19 • May 28 '19

Thanks for your article! I think env-cmd needs -f argument to load the custom file correctly. Otherwise it fails and load .env file by default.

Donghyuk (Jacob) Jang • Jun 10 '19

Thanks for this information. When this article was written, it was using env-cmd version 8.0.2. It was not required -f option. I also just tested the latest version which is 9.0.3 without the parameter and caused an issue. As a result, when pointing a custom env file, it is required. Thank you so much @foxbit19 .

Julien Eric • Oct 8 '19

By far the simplest solution. Good stuff!

Omar Dulaimi • Mar 19 '20

Much thanks, it works.

Grachev Mikhail • Oct 28 '20

In addition to using environment variables I can recommend the tool github.com/dotenv-linter/dotenv-li... - it’s a lightning-fast linter for .env files.
Maybe it would be useful for you.

Bruno Ochotorena • Jun 9 '21

Thanks, this work flawless.

Akshay Kakade • Jul 31 '20

Will it apply with the yarn build command?