Using NODE_ENV with multiple environments in JavaScript projects

Question

I work on many projects that run on Express servers, whether they are front-end (i.e. React.js) codebases or server-side Node.js codebases.

Many times with the front-end codebases I would load conditional configuration based on NODE_ENV, such as the URL of the restful API that the front-end makes requests to.

I many times also used NODE_ENV to conditionally load things like DB configuration for server-side Node.js projects.

On a project that consisted of development, staging, and production (3 environments), I would usually set up my code to load configuration based on the NODE_ENV being set to any one of those 3 environments (and maybe also "local").

I was recently working on a project that was referring to the production environment as "live."

When I decided to set the NODE_ENV=live for this environment, a coworker pointed out a major flaw with this approach.

It seems that Express and some other libraries for Node.js latch onto the fact that you will either be using "production" or "development" as your NODE_ENV and using other names for your environments can have unexpected effects.

For example, Express needs NODE_ENV=production in order to run in "production" mode. According to the Express docs "Tests indicate that just doing this can improve app performance by a factor of three!"

Basically, I'm curious if it is considered common practice to set the NODE_ENV to values other than "development" and "production," like I've been doing in my projects.

I feel that if I'm going to deploy my code to the development or staging environments on the cloud, I don't think they should run in a different Express "mode" than the production environment.

Does it make more sense to maintain configurations separate from NODE_ENV?

For example, does it make sense to base your configuration off of a variable like APP_ENV, while ensuring that NODE_ENV is either "development" or "production" for frameworks/packages like Express.

Answer 1

NODE_ENV should be set to either development or production in traditional sense.

The reason being, when you're building a front-end application (React, etc), you either build the application in development mode or production mode. For example, in development mode, you will watch for changes and build continuously. In production mode, you minify the code and optimize it for size.

In case of a node server, the NODE_ENV refers to what mode you start your application with. For example, in development mode, you configure your server and install all devDependencies and watch for changes and live reload the server. And in production mode, you only install dependencies and start the server with optimized configuration.

Now talking about different production environments, say staging, pre-live, live, etc, you should use a separate ENV variable for this. Except local, all other environments are considered production environments and your app should be built with and start in production mode in these environments.

You usually load different configurations, say api keys, urls for each environment. These should be differentiated with a separate ENV variable like APP_ENV.

I usually use APP_ENV to differentiate between staging and live environments.

This is how the package.json will look like with different start scripts for different environments

"scripts": {
  "start:local": "NODE_ENV=development APP_ENV=local your-start-script",
  "start:staging": "NODE_ENV=production APP_ENV=staging your-start-script",
  "start:live": "NODE_ENV=production APP_ENV=live your-start-script",
}

You will need to start the app with the right start script in each environment.

Answer 2

NODE_ENV is used to differentiate between development and production instances. It is not a good idea to run production code without NODE_ENV=production. NODE_ENV=development is usually not that important, because libraries usually just check to see if NODE_ENV !== 'production'. So if you want to have multiple production node environments, or production-like environments, each of them should set NODE_ENV=production. That said, you can definitely set other environment variables to whatever values you desire, and read them back from node at runtime.

A reasonable example would be to have a local staging and production versions of your configuration. In this case, I would recommend having NODE_ENV be just one of the parameters you set up for each environment. For instance, you might want three different databases for each of local, staging and production but set NODE_ENV to development on local, and production for both staging and production.

Since the variables will be shell variables, you will need a way of loading certain environment variables on the target operating system prior to running the server. Modules like https://www.npmjs.com/package/dotenv look promising for this purpose.