Nest.js Config Module

Configuration module for Nest framework (node.js)

Installation

npm install --save nestjs-config-module

Usage

You have to import the Module ConfigModule and initialize it with the forRoot function, this fetches a Javascript object with the loader function, then maps and validates that to the schema

This Module is not used as injection dependency directly, but rather its schema class and subclasses.

import { Module } from '@nestjs/common';
import { ConfigModule, envJsonLoaderFactory } from 'nestjs-config-module';
import { IsOptional, ValidateNested, IsArray, ArrayUnique, IsString, IsIn } from 'class-validator';
import { Type } from 'class-transformer';
import { LogLevel } from "@nestjs/common";

export class LogConfiguration {
    @IsArray()
    @ArrayUnique()
    @IsString({
        each: true
    })
    @IsIn(['log', 'error', 'warn', 'debug', 'verbose'], {
        each: true
    })
    levels: LogLevel[] = ['log', 'error', 'warn'];
}

export class Configuration {
    @IsOptional()
    host?: string;
    @ValidateNested() @Type(() => LogConfiguration)
    log = new LogConfiguration();
}

@Module({
  imports: [ConfigModule.forRoot({
    isGlobal: true,
    loader: envJsonLoaderFactory('DEMO_'),
    schema: Configuration,
  })],
})
export class AppModule {}

import { Injectable } from '@nestjs/common';
import { Configuration } from 'app.module';

@Injectable()
export class FooService {
    constructor(
        private configuration: Configuration,
    ) {}
}

import { Injectable } from '@nestjs/common';
import { LogConfiguration } from 'app.module';

@Injectable()
export class BarService {
    constructor(
        private logConfiguration: LogConfiguration,
    ) {}
}

Loaders

this module comes with 2 builtin loaders:

• envJsonLoaderFactory
• jsonFileLoaderFactory

For the documentation on how to use the envJsonLoader see: env-json-parser

It's also possible to implement your own loader, it just needs to be a function that returns a Promise which resolves an object

ConfigModule.forRoot({
  isGlobal: true,
  loader: (): Promise<object> => {
    return Promise.resolve({
      host: 'localhost'
   })
  },
  schema: Configuration,
})