nestjs issue with variable in .env file

Question

Im using NestJS framework to build a rest api, i have a issue getting the environment variables.

I have a .env with a variable "SMB_SHARE" with a path string, when i pass this variable to a class constructor of a smb2 libray, this throw an error, the string provided by the environment variable is invalid.

The environment variable is this:

SMB_SHARE=\\10.00.0.000\some_path

When i use console log in the code the variable is ok, is a string and has the correct string value. But when i pass it to the constructor, it throw the error.

I pass the string directly to the constructor, and it work fine, the others environment variables of the constructor are setted correctly (like the username and password). Only the SMB_SHARE variable is throwing the error.

I dont have idea what is the problem here. Can someone help me with this issue?

I show some examples:

constructor(private config: ConfigService) {
    console.log('VAR', config.get<string>('SMB_SHARE'));
    //This show the correctly string variable value

    const share = config.get<string>('SMB_SHARE');

    this.sambaClient = new SMB2({
      share: '\\\\10.00.0.000\\some_path', //WORK
      //share: share, FAIL
      //share: config.get<string>('SMB_SHARE'), FAIL
      //share: process.env.SMB_SHARE, FAIL
      domain: '',
      username: config.get<string>('SMB_USERNAME'),
      password: config.get<string>('SMB_PASSWORD'),
      debug: true,
      autoCloseTimeout: 0,
    })
}

The .env file is like this:

SMB_SHARE=\\\\10.00.0.000\\some_path
SMB_USERNAME=user
SMB_PASSWORD=secret

Answer 1

More than likely, what is happening is JavaScript is escaping the extra \. This is unescaped when the print happens, so it looks proper (i.e. console.log(process.env.SMB_SHARE) will print \\\\10.0.0.0\\some_path, but in reality, the variable is now \\\\\\\\10.0.0.0\\\\some_path). I ended up creating a mock of this using a text file called ./temp/.env and making use of the fs module from Node (which is what dotenv uses, which is what @nestjs/config uses. You can see below the cat (print) of the file, and the two different methods while using node to read the file

~/Documents/code                                                               
▶ cat ./temp/.env
HOST=\\\\127.0.0.1:3000\\path


~/Documents/code                                                               
▶ node
Welcome to Node.js v12.18.2.
Type ".help" for more information.
> const { readFileSync } = require('fs');
undefined
> readFileSync('./temp/.env').toString()
'HOST=\\\\\\\\127.0.0.1:3000\\\\path\n\n'
> console.log(readFileSync('./temp/.env').toString())
HOST=\\\\127.0.0.1:3000\\path

The solution here, would be to change your .env file to be the exact string you're wanting to pass on to the configuration (probably \\10.0.0.0\some_path)

Answer 2

you have to implement the config module.

start with

npm i --save @nestjs/config

then add the configModule in your appModule:

import { ConfigModule } from '@nestjs/config';

@Module({
  imports: [ConfigModule.forRoot()],
 })
 export class AppModule {}