Does not return value on Interpolation of variables

[lazuee]

Prerequisites

• I have written a descriptive issue title
• I have searched existing issues to ensure the bug has not already been reported

Fastify version

4.10.0

Plugin version

No response

Node.js version

20.12.2

Operating system

Windows

Operating system version (i.e. 20.04, 11.3, 10)

23H2

Description

import envSchema, { JSONSchemaType } from 'env-schema';

export interface Env {
  DATABASE_USER: string;
  DATABASE_PASSWORD: string;
  DATABASE_HOST: string;
  DATABASE_PORT: number;
  DATABASE_NAME: string;
  DATABASE_URL: string;
}

const schema: JSONSchemaType<Env> = {
  type: 'object',
  required: ['DATABASE_USER', 'DATABASE_PASSWORD', 'DATABASE_HOST', 'DATABASE_PORT', 'DATABASE_NAME', 'DATABASE_URL'
  ],
  properties: {
    DATABASE_USER: {
      type: 'string',
    },
    DATABASE_PASSWORD: {
      type: 'string',
    },
    DATABASE_HOST: {
      type: 'string',
    },
    DATABASE_PORT: {
      type: 'number',
    },
    DATABASE_NAME: {
      type: 'string',
    },
    DATABASE_URL: {
      type: 'string',
    },
  },
};

const env = envSchema({
  dotenv: true,
  schema,
});

console.log(env.DATABASE_URL); // result: mysql://${DATABASE_USER}:${DATABASE_PASSWORD}@${DATABASE_HOST}:${DATABASE_PORT}/${DATABASE_NAME}?ssl-mode=REQUIRED
console.log(process.env.DATABASE_URL); // expected result: mysql://root:pass@localhost:3306/db_name?ssl-mode=REQUIRED

DATABASE_USER="root"
DATABASE_PASSWORD="pass"
DATABASE_HOST="localhost"
DATABASE_PORT="3306"
DATABASE_NAME="db_name"
DATABASE_URL="mysql://${DATABASE_USER}:${DATABASE_PASSWORD}@${DATABASE_HOST}:${DATABASE_PORT}/${DATABASE_NAME}?ssl-mode=REQUIRED"

Link to code that reproduces the bug

No response

Expected Behavior

No response

[Eomm]

We don't use any additional plugins, you need to add the https://www.npmjs.com/package/dotenv-expand one.

We may implement a plugins option in this plugin as we did for ajv https://fastify.dev/docs/latest/Reference/Validation-and-Serialization/#ajv-plugins
but I would not add this dep to our dependancies.

[lazuee]

Thank you for the suggestion. I added the dotenv-expand package, and it's now working properly.