.forRoot(): environment variable key/value pairs are parsed and resolved. registers the ConfigService provider.

ConfigService: several options for accessing. first need to inject ConfigService

• Module Options
  • Custom env file path: To specify another path and also multiple paths.
  • Use module globally: declare it as a global module
  • Cache environment variables: As accessing process.env can be slow, to increase the performance of ConfigService#get method when it comes to variables stored in process.env

Custom configuration files

1. also manage custom files such as YAML files
2. Configuration namespaces: return a "namespaced" configuration object with the registerAs() function

Validation: It is standard practice to throw an exception during application startup if required environment variables haven't been provided or if they don't meet certain validation rules.

1. Joi built-in validator
2. A custom validate() function

Expandable variables: supports environment variable expansion

Using in the main.ts: it can still be used in the main.ts file

예시

Managing Configs in NestJs.

How to setup different environments in Nest.js

Managing multiple environments in NestJS