Environment Variables

Any string value in a config file can reference a process.env variable using the syntax:

${env.VAR_NAME}

Interpolation happens inside loadConfig(), before Zod validation. This means environment variables can be used in any string field — base URL, headers, auth values, request params, and request body strings.

---

Usage

baseUrl: "${env.API_BASE_URL}"

auth:
  type: apiKey
  in: header
  name: x-api-key
  value: "${env.MY_API_KEY}"

headers:
  X-Tenant: "${env.TENANT_ID}"

requests:
  users:
    path: /users
    params:
      region: "${env.REGION}"

---

Behavior

• Variables are resolved from process.env at load time.
• If the variable is not set, fraft throws an error immediately at startup. There is no default or fallback syntax.
• Interpolation only applies to string values. A numeric field like limit: ${env.LIMIT} will fail Zod validation — use a string field and coerce it if needed.

---

Loading .env files

fraft does not load .env files automatically. You should load them before constructing the client:

import 'dotenv/config'; // or: import dotenv from 'dotenv'; dotenv.config();
import { FraftClient } from '@go-denki/fraft';

const client = new FraftClient({ config: 'api.yaml' });

---

Example

Given this .env:

API_BASE_URL=https://api.example.com
API_KEY=secret-key-123

And this config:

version: 1
baseUrl: "${env.API_BASE_URL}"
auth:
  type: apiKey
  in: header
  name: x-api-key
  value: "${env.API_KEY}"
requests:
  users:
    path: /users

fraft resolves the config at startup to:

{
  "version": 1,
  "baseUrl": "https://api.example.com",
  "auth": {
    "type": "apiKey",
    "in": "header",
    "name": "x-api-key",
    "value": "secret-key-123"
  },
  "requests": {
    "users": { "path": "/users" }
  }
}