How to access and cast environment variables

In most use cases there will be different configurations between environments (e.g. database credentials).

Instead of writing those credentials into configuration files, variables can be defined in a .env file at the root of the application:

# path: .env

DATABASE_PASSWORD=acme

To customize the path of the .env file to load, set an environment variable called ENV_PATH before starting the application:

ENV_PATH=/absolute/path/to/.env npm run start

Accessing environment variables

Variables defined in the .env file are accessible using process.env.{variableName} anywhere in configuration and application files.

In configuration files, a env() utility allows defining defaults and casting values:

./config/database.js

module.exports = ({ env })  ({
  connections: {
    default: {
      settings: {
        password: env('DATABASE_PASSWORD'),
      },
    },
  },
});

./config/database.ts

export default ({ env })  ({
  connections: {
    default: {
      settings: {
        password: env('DATABASE_PASSWORD'),
      },
    },
  },
});

note

The syntax property-name: env('VAR', 'default-value') uses the value stored in the .env file. If there is no specified value in the .env file the default value is used.

Casting environment variables

The env() utility can be used to cast environment variables to different types:

// Returns the env if defined without casting it
env('VAR', 'default');

// Cast to integer (using parseInt)
env.int('VAR', 0);

// Cast to float (using parseFloat)
env.float('VAR', 3.14);

// Cast to boolean (check if the value is equal to 'true')
env.bool('VAR', true);

// Cast to JS object (using JSON.parse)
env.json('VAR', { key: 'value' });

// Cast to array (syntax: ENV_VAR=[value1, value2, value3] | ENV_VAR=["value1", "value2", "value3"])
env.array('VAR', [1, 2, 3]);

// Cast to date (using new Date(value))
env.date('VAR', new Date());

// Returns the env matching oneOf union types
env.oneOf('UPLOAD_PROVIDER', ['local', 'aws'], 'local')