What is NODE_ENV in Node ?

In Node.js, NODE_ENV is an environment variable used to define the current environment in which the Node.js application is running. It plays a crucial role in configuring the behavior of the application based on different environments such as development, staging, and production. This article delves into the significance of NODE_ENV, its usage, and best practices for managing environments in Node.js applications.

NODE_ENV is a standard environment variable in Node.js that represents the current environment of the application. The NODE_ENV environment variable specifies the environment in which an application is running (usually, development or production). It is a string that typically takes one of the following values:

• development: Indicates that the application is running in a development environment.
• production: Indicates that the application is running in a production environment.
• test: Indicates that the application is running in a testing environment.

Setting NODE_ENV to “production” makes Express:

• Cache view templates.
• Cache CSS files generated from CSS extensions.
• Generate less verbose error messages.

The NODE_ENV variable is essential for several reasons:

• Configuration Management: It allows developers to configure the application differently based on the environment, such as using different database connections, logging levels, or error handling strategies.
• Optimization: In production environments, developers can optimize the application for performance, minimize logging, and enable caching mechanisms to enhance efficiency.
• Debugging: Setting NODE_ENV to development enables additional debugging features and provides more detailed error messages, making it easier to troubleshoot issues during development.
• Security: By distinguishing between different environments, developers can implement security measures appropriate for each environment, such as stricter access controls in production.

Examples of environment variables:

USER_ID=239482
KEY=foobar

The above environment variables can be accessed like:

process.env.USER_ID
process.env.KEY

The process.env object is a global Node object, and variables are passed as strings. The variable names are all uppercase, with words separated by an underscore is a long-followed convention still used.

NODE_ENV works like any other environment variable. How to set it depends on the platform being used.

On Linux and OSX: export NODE_ENV=production
On Windows: $env:NODE_ENV = 'production'

Set at the time of starting the application

On all platforms, we can explicitly set the NODE_ENV at the time of starting the application like: 

NODE_ENV=production node app.js

Accessing NODE_ENV

We can access NODE_ENV like any other environment variable using the process and env of NodeJS as we have already seen while learning about environment variables.

process.env.NODE_ENV

We can write environment-specific code by checking the value of NODE_ENV by using process.env.NODE_ENV.

Example 1: Below is a code snippets for reference on accessing and using NODE_ENV:

const environment = process.env.NODE_ENV;
if (environment === 'production') {
    /* Do something specific
    to production environment. */
}

Example 2: Below is a code snippets for reference on accessing and using NODE_ENV:

const environment = process.env.NODE_ENV;
if (environment === 'development') {
    // connect to local database.
}
else {
    // connect to hosted database.
}

Note that:

• We can use app.get(‘env’) function provided by express to get the value of NODE_ENV but it defaults to “development” rather than production otherwise.
• If NODE_ENV is not set explicitly for the environment and accessed using process.env then it will be undefined.
• It is a bad idea to set NODE_ENV from within an application. In such a case, it will only be applied to the process from which it was set.

The node application contains .env file in the root of your project directory and it acts as a hidden file that is used to pass environment variables to the application. It is a secret file that cannot be accessed by anyone except the developer and hence can be used to store private/secret/ hidden data ( data that you cannot afford to make public, i.e., it is vulnerable data), it can be used to store API keys from external services. 

The .env is a shell file, eliminating the need to wrap names or values in quotes. Yet another meticulous rule is that there cannot be space around the equals sign when you are assigning values to the variables, e.g. VAR_NAME=value. Generally, the variable definition is provided on a separate line.

To effectively manage environments using NODE_ENV, consider the following best practices:

• Consistency: Ensure consistent usage of NODE_ENV across all environments to avoid confusion and inconsistencies in configuration.
• Security: Avoid hardcoding sensitive information in the application code, especially in development environments, and utilize environment variables securely.
• Version Control: Do not store environment-specific configuration files containing sensitive information in version control systems. Instead, use environment variables or secure vaults.
• Testing: Test the application thoroughly in different environments to ensure that configuration changes do not introduce unexpected behavior or vulnerabilities.

In Node.js development, NODE_ENV is a critical environment variable used to configure applications based on different environments. By leveraging NODE_ENV effectively, developers can ensure consistent behavior, optimize performance, and enhance security across development, staging, and production environments. Understanding and utilizing NODE_ENV appropriately is essential for building robust and scalable Node.js applications.