@workspace/env

Environment variable validation using t3-env and Zod schemas. Provides runtime validation, TypeScript types, and CI-friendly configuration patterns.

Runtime Validation

Call loadServerEnv() inside functions, not at module top-level. This ensures environment variables load correctly in serverless and edge environments.

Package Exports

Core Exports

loadServerEnv()

Loads and validates server-side environment variables at runtime.

Function-scoped usage

import { loadServerEnv } from "@workspace/env/server";

export async function handler() {
  const env = loadServerEnv();

  // Access validated variables
  const secret = env.BETTER_AUTH_SECRET;
  const apiKey = env.AUTUMN_SECRET_KEY;
}

Available Variables

Heads up

Never call loadServerEnv() at module top-level. Serverless functions may execute module code in unexpected contexts, causing initialization errors.

Correct Usage

Runtime loading pattern

// ✅ Correct - function scoped
export async function GET() {
  const { AUTUMN_SECRET_KEY } = loadServerEnv();
  const client = new Autumn({ secretKey: AUTUMN_SECRET_KEY });
}

// ❌ Wrong - module level
const { AUTUMN_SECRET_KEY } = loadServerEnv();
export async function GET() {
  const client = new Autumn({ secretKey: AUTUMN_SECRET_KEY });
}

nextEnv

Build-safe environment access for Next.js configuration.

next.config.ts usage

import { nextEnv } from "@workspace/env/next";

export default {
  env: {
    APP_BASE_URL: nextEnv.APP_BASE_URL ?? "http://localhost:3000",
  },
};

nextEnv vs loadServerEnv()

Schema differences

// loadServerEnv() - Runtime validation (strict)
{
  GOOGLE_CLIENT_SECRET: z.string().min(1) // Required in production
}

// nextEnv - Build-time access (relaxed)
{
  GOOGLE_CLIENT_SECRET: z.string().min(1).optional() // Optional for CI builds
}

The nextEnv schema allows builds to succeed without server secrets, enabling CI/CD pipelines to build applications before deployment.

publicEnv

Client-side environment variables with NEXT_PUBLIC_ prefix.

Client usage

import { publicEnv } from "@workspace/env/client";

export function DashboardLink() {
  return (
    <a href={publicEnv.NEXT_PUBLIC_DASHBOARD_BASE_URL}>
      Go to Dashboard
    </a>
  );
}

Available Variables

Client environment variables

{
  NEXT_PUBLIC_CONVEX_URL: string;
  NEXT_PUBLIC_CONVEX_SITE_URL: string;
  NEXT_PUBLIC_DASHBOARD_BASE_URL: string;
  NEXT_PUBLIC_POSTHOG_KEY?: string;
  NEXT_PUBLIC_POSTHOG_HOST?: string;
}

Client Exposure

All NEXT_PUBLIC_ variables are inlined at build time and visible in browser JavaScript. Never use this prefix for secrets.

Validation Patterns

Production vs Development

Environment validation adjusts based on NODE_ENV:

Environment-specific validation

const isProd = process.env.NODE_ENV === "production";

export const serverEnv = createEnv({
  server: {
    GOOGLE_CLIENT_SECRET: isProd
      ? z.string().min(1) // Required in production
      : z.string().min(1).default("placeholder-secret"), // Default in dev
  },
  // ...
});

Development defaults allow rapid prototyping. Production validation enforces security requirements.

URL Validation

URLs undergo format and protocol validation:

HTTPS enforcement in production

const httpsOrLoopbackUrl = z
  .string()
  .url()
  .refine(
    (value) => {
      if (!isProd) return true; // Any URL in development

      if (value.startsWith("https://")) return true;

      // Allow http://localhost in production for local builds
      const { hostname, protocol } = new URL(value);
      const isLoopback = hostname === "localhost" || hostname === "127.0.0.1";
      return isLoopback && protocol === "http:";
    },
    { message: "URL must use https:// in production" }
  );

This prevents accidental HTTP usage in production while allowing local development.

Optional with Defaults

Non-critical variables use optional validation with defaults:

Analytics example

{
  NEXT_PUBLIC_POSTHOG_KEY: z.string().min(1).optional(),
  NEXT_PUBLIC_POSTHOG_HOST: z.string().url().optional(),
}

Missing analytics configuration disables tracking rather than failing application startup.

CI/CD Integration

Build Without Secrets

Two approaches for CI builds:

1. nextEnv Pattern (Recommended)

Using nextEnv in build scripts

import { nextEnv } from "@workspace/env/next";

// Builds succeed without server secrets
const appUrl = nextEnv.APP_BASE_URL ?? "http://localhost:3000";

2. SKIP_ENV_VALIDATION (Fallback)

CI environment

# .env.ci
SKIP_ENV_VALIDATION=true
NEXT_PUBLIC_CONVEX_URL=https://placeholder.convex.cloud

The skip flag disables all validation. Use nextEnv when possible for partial validation.

Placeholder URLs

CI-safe placeholder values:

Development placeholders

NEXT_PUBLIC_CONVEX_URL=https://placeholder.convex.cloud
NEXT_PUBLIC_CONVEX_SITE_URL=https://placeholder.convex.site
GOOGLE_CLIENT_ID=placeholder-google-client-id
GOOGLE_CLIENT_SECRET=placeholder-google-client-secret

Applications detect placeholders and adjust behavior (e.g., convexClient returns null).

Error Handling

Validation Failures

Missing or invalid variables produce detailed errors:

Example error output

❌ Invalid environment variables:
  - GOOGLE_CLIENT_SECRET: Required
  - APP_BASE_URL: Invalid url
  - NEXT_PUBLIC_CONVEX_URL: Required

Multiple errors appear together, showing all issues at once.

Runtime vs Build-time Errors

Error timing

// Build-time error (nextEnv)
import { nextEnv } from "@workspace/env/next";
// Validates on import - fails build if invalid

// Runtime error (loadServerEnv)
const env = loadServerEnv();
// Validates on function call - fails at runtime if invalid

Use nextEnv for build configuration. Use loadServerEnv() for request handlers.

Usage Patterns

API Route Configuration

app/api/route.ts

import { loadServerEnv } from "@workspace/env/server";
import { Autumn } from "autumn-js";

export async function POST(request: Request) {
  const { AUTUMN_SECRET_KEY } = loadServerEnv();

  const client = new Autumn({ secretKey: AUTUMN_SECRET_KEY });
  // Use client...
}

Server Component Usage

app/dashboard/page.tsx

import { loadServerEnv } from "@workspace/env/server";

export default async function DashboardPage() {
  const { DASHBOARD_BASE_URL } = loadServerEnv();

  return (
    <div>
      <p>Dashboard URL: {DASHBOARD_BASE_URL}</p>
    </div>
  );
}

Middleware Configuration

middleware.ts

import { loadServerEnv } from "@workspace/env/server";

export function middleware(request: NextRequest) {
  const { DASHBOARD_BASE_URL } = loadServerEnv();

  if (request.nextUrl.pathname.startsWith("/dashboard")) {
    return NextResponse.redirect(new URL("/", DASHBOARD_BASE_URL));
  }
}

Testing

Test Environment Setup

.env.test

# Required for tests
NEXT_PUBLIC_CONVEX_URL=https://test.convex.cloud
GOOGLE_CLIENT_ID=test-client-id
GOOGLE_CLIENT_SECRET=test-client-secret
AUTUMN_SECRET_KEY=am_sk_test_placeholder

# Skip validation if using mocks
SKIP_ENV_VALIDATION=true

Mocking Environment Variables

Test setup

import { vi } from "vitest";

vi.mock("@workspace/env/server", () => ({
  loadServerEnv: vi.fn(() => ({
    GOOGLE_CLIENT_ID: "test-client-id",
    GOOGLE_CLIENT_SECRET: "test-secret",
    AUTUMN_SECRET_KEY: "am_sk_test_key",
    APP_BASE_URL: "http://localhost:3000",
    DASHBOARD_BASE_URL: "http://localhost:3001",
  })),
}));

Testing Validation Logic

Validation tests

import { expect, test } from "vitest";
import { loadServerEnv } from "@workspace/env/server";

test("requires GOOGLE_CLIENT_SECRET in production", () => {
  process.env.NODE_ENV = "production";
  delete process.env.GOOGLE_CLIENT_SECRET;

  expect(() => loadServerEnv()).toThrow("GOOGLE_CLIENT_SECRET");
});

test("provides default in development", () => {
  process.env.NODE_ENV = "development";
  delete process.env.GOOGLE_CLIENT_SECRET;

  const env = loadServerEnv();
  expect(env.GOOGLE_CLIENT_SECRET).toBe("placeholder-google-client-secret");
});

Security Considerations

Server-Only Variables

Server variables never reach the client:

Type safety prevents exposure

// ❌ TypeScript error - server env not accessible in client
"use client";
import { loadServerEnv } from "@workspace/env/server";

const env = loadServerEnv(); // Build error

Package configuration prevents server environment imports in client code.

Secret Validation

Secrets require minimum lengths:

Secret constraints

{
  BETTER_AUTH_SECRET: z.string().min(32),
  AUTUMN_SECRET_KEY: z.string().min(20),
}

This enforces security baselines for cryptographic operations.

Environment Leakage Prevention

Error messages never expose secret values:

Safe error handling

// Error message
"GOOGLE_CLIENT_SECRET: Required"

// NOT
"GOOGLE_CLIENT_SECRET: Expected 'sk_live_abc123...', received undefined"

Validation errors indicate missing/invalid variables without revealing actual values.

Architecture

Validation Strategy

Environment validation occurs at three points:

Build Time - nextEnv validates during Next.js build

Module Load - publicEnv validates when importing client package

Runtime - loadServerEnv() validates on function execution

This layered approach catches issues early while supporting CI/CD workflows.

Type Safety

Validated environment objects provide full TypeScript inference:

Type inference

const env = loadServerEnv();

// TypeScript knows these properties exist
env.GOOGLE_CLIENT_ID; // string
env.HSTS_PRELOAD;     // "0" | "1" | undefined

// Autocomplete works
env.AUTUMN_ // Suggests AUTUMN_SECRET_KEY

No manual type annotations required after validation.

Common Patterns

Configuration Objects

Group related variables for subsystems:

Grouped exports

// packages/env/src/server.ts
export function getAuthConfig() {
  const env = loadServerEnv();
  return {
    googleClientId: env.GOOGLE_CLIENT_ID,
    googleClientSecret: env.GOOGLE_CLIENT_SECRET,
    betterAuthSecret: env.BETTER_AUTH_SECRET,
  };
}

URL Construction

Helper functions for consistent URL building:

URL utilities

// packages/env/src/url.ts
export function getDashboardUrl(path: string = "/") {
  const { DASHBOARD_BASE_URL } = loadServerEnv();
  return new URL(path, DASHBOARD_BASE_URL).toString();
}

// Usage
const loginUrl = getDashboardUrl("/sign-in");

AI-Assisted Configuration

AI assistants understand environment patterns:

Natural Language to Config

Describe needed configuration like "add Stripe integration" and AI generates appropriate schema definitions with validation rules automatically.

AI-generated schema

// Prompt: "Add Stripe configuration"
{
  STRIPE_SECRET_KEY: isProd
    ? z.string().min(1).startsWith("sk_live_")
    : z.string().min(1).default("sk_test_placeholder"),
  STRIPE_WEBHOOK_SECRET: isProd
    ? z.string().min(1)
    : z.string().min(1).default("whsec_test_placeholder"),
}