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Environment Variables

This project uses dotenv-extended to load environment variables. By using ts-tools, you do not need to include additional libraries to load env vars, as this can be done for you automatically:

import { loadEnv } from `ts-tools`;
const env = loadEnv();

This decouples your project from the explicit developer dependency on the env var tool. Using loadEnv to init your environment variables has a number of additional benefits.

  • Schema validation
  • Default values
  • Flexible configuration options
  • Self-documenting README, see docs

Table of Contents

Schema

Your project should include a .env.schema file, which should define every environment variable you intend to use with an optional regex for validating values. For example:

NODE_ENV=[a-z]+
API_TOKEN=

This schema file should be committed and tracked in VCS. For more details on configuring your schema, see dotenv-extended schema

Default Values

Your project should also include a .env.defaults file, which should define every environment variable from .env.schema which should have a default value. For example:

NODE_ENV=dev

This defaults file should be committed and tracked in VCS. If no .env file is present, the .env.defaults will be used for all variables. If a .env file exists and does not define a variable, the default value from .env.defaults will be used. If .env exists and defines all variables and values, the .env.defaults is ignored.

Validation

A few important things happen when loading your environment variables:

import { loadEnv } from `ts-tools`;
const env = loadEnv();
  • When loadEnv is invoked, if a variable is defined in .env.schema and no value is defined in either .env.defaults or .env, an exception will be thrown stating the variable is missing a value.
  • If the loaded value does not match the specific regex from .env.schema, a validation error will be thrown.
  • If either .env or .env.defaults defines variables that do not exist in .env.schema, an exception will be thrown. This validation ensures that changes to environment variables over time never leave a developer's local environment in an inconsistent state.