Env Config Validator

Env Config Validator

Before generating any output, read config/defaults.md and adapt all patterns, imports, and code examples to the user's configured stack.

Process

1. Read the .env file (and .env.local, .env.development, .env.production if they exist).
2. Scan the codebase for process.env.* and import.meta.env.* references.
3. Compare: find missing variables, unused variables, and misconfigurations.
4. Detect security issues: sensitive values, duplicates, invalid formats.
5. Generate or update .env.example and optionally a typed env validation schema.

Detection Rules

Missing Variables

Scan all .ts, .tsx, .js, .jsx files for process.env.VARIABLE_NAME patterns. Flag any variable referenced in code but absent from .env.

🔴 MISSING: DATABASE_URL
   Referenced in: lib/prisma.ts:3, lib/db.ts:7
   Not defined in any .env file

🔴 MISSING: NEXTAUTH_SECRET
   Referenced in: lib/auth.ts:12
   Not defined in any .env file

Unused Variables

Variables defined in .env but never referenced in code.

🟡 UNUSED: LEGACY_API_URL
   Defined in: .env:14
   No references found in codebase

Exclude from this check: variables used by frameworks implicitly (e.g., PORT, NODE_ENV, HOSTNAME, NEXT_PUBLIC_* referenced in client code).

Empty Values

🟡 EMPTY: SMTP_HOST=
   Defined in: .env:22
   Variable exists but has no value

Duplicate Definitions

🔴 DUPLICATE: NEXT_PUBLIC_API_URL
   Line 5: NEXT_PUBLIC_API_URL=https://api.example.com
   Line 18: NEXT_PUBLIC_API_URL=https://staging.example.com
   Last definition wins — likely unintentional

Invalid Format

🟡 FORMAT: PORT=three thousand
   Expected: numeric value
   Suggested: PORT=3000

🟡 FORMAT: DEBUG=yes
   Expected: boolean-like value (true/false, 1/0)
   Suggested: DEBUG=true

Security Issues

Flag variables that appear to contain real secrets (not placeholders):

🔴 SECRET EXPOSED: STRIPE_SECRET_KEY=sk_live_abc123...
   This looks like a real API key. Ensure .env is in .gitignore.

🔴 SECRET EXPOSED: DATABASE_URL=postgresql://admin:realpassword@prod-db:5432/app
   Connection string contains credentials.

Check that .gitignore includes .env and .env.local. Warn if it does not.

Generate .env.example

Produce a .env.example file with all required variables, replacing real values with descriptive placeholders.

# Database
DATABASE_URL="postgresql://user:password@localhost:5432/dbname"

# Authentication (generate with: openssl rand -base64 32)
NEXTAUTH_SECRET="your-nextauth-secret-here"
NEXTAUTH_URL="http://localhost:3000"

# External APIs
STRIPE_SECRET_KEY="sk_test_..."
STRIPE_PUBLISHABLE_KEY="pk_test_..."

# Email
SMTP_HOST="smtp.example.com"
SMTP_PORT="587"
SMTP_USER="your-email@example.com"
SMTP_PASS="your-smtp-password"

# Public (exposed to browser)
NEXT_PUBLIC_API_URL="http://localhost:3000/api"
NEXT_PUBLIC_APP_NAME="My App"

Rules for placeholder generation:

• URLs: use http://localhost:* or https://example.com
• Secrets/keys: use your-*-here or the service's test key prefix (e.g., sk_test_...)
• Booleans: use true or false
• Numbers: use the typical default (e.g., 3000 for PORT)
• Connection strings: use protocol://user:password@localhost:port/dbname

Generate Typed Env Schema

T3 Env Pattern (Next.js)

// env.ts
import { createEnv } from "@t3-oss/env-nextjs";
import { z } from "zod";

export const env = createEnv({
  server: {
    DATABASE_URL: z.string().url(),
    NEXTAUTH_SECRET: z.string().min(1),
    NEXTAUTH_URL: z.string().url().optional(),
    STRIPE_SECRET_KEY: z.string().startsWith("sk_"),
    SMTP_HOST: z.string().min(1),
    SMTP_PORT: z.coerce.number().int().min(1).max(65535),
    SMTP_USER: z.string().email(),
    SMTP_PASS: z.string().min(1),
    NODE_ENV: z.enum(["development", "test", "production"]).default("development"),
  },
  client: {
    NEXT_PUBLIC_API_URL: z.string().url(),
    NEXT_PUBLIC_APP_NAME: z.string().min(1),
  },
  runtimeEnv: {
    DATABASE_URL: process.env.DATABASE_URL,
    NEXTAUTH_SECRET: process.env.NEXTAUTH_SECRET,
    NEXTAUTH_URL: process.env.NEXTAUTH_URL,
    STRIPE_SECRET_KEY: process.env.STRIPE_SECRET_KEY,
    SMTP_HOST: process.env.SMTP_HOST,
    SMTP_PORT: process.env.SMTP_PORT,
    SMTP_USER: process.env.SMTP_USER,
    SMTP_PASS: process.env.SMTP_PASS,
    NODE_ENV: process.env.NODE_ENV,
    NEXT_PUBLIC_API_URL: process.env.NEXT_PUBLIC_API_URL,
    NEXT_PUBLIC_APP_NAME: process.env.NEXT_PUBLIC_APP_NAME,
  },
});

Plain Zod Pattern (non-Next.js)

// env.ts
import { z } from "zod";

const envSchema = z.object({
  DATABASE_URL: z.string().url(),
  PORT: z.coerce.number().int().default(3000),
  NODE_ENV: z.enum(["development", "test", "production"]).default("development"),
  API_KEY: z.string().min(1),
});

export const env = envSchema.parse(process.env);
export type Env = z.infer;

Naming Convention Audit

Flag variables that don't follow standard prefixes:

| Prefix | Purpose | |---|---| | DATABASE_ | Database configuration | | NEXT_PUBLIC_ | Client-exposed variables (Next.js) | | NEXTAUTH_ | NextAuth.js / Auth.js configuration | | AUTH_ | Authentication-related | | SMTP_ / EMAIL_ | Email service | | STRIPE_ / PAYMENT_ | Payment provider | | AWS_ / S3_ | AWS services | | REDIS_ | Redis configuration |

🔵 NAMING: apiKey
   Convention: use SCREAMING_SNAKE_CASE with descriptive prefix
   Suggested: EXTERNAL_API_KEY

Output Format

## Env Validation Report

### Summary
| Category | Count |
|----------|-------|
| 🔴 Missing | N |
| 🔴 Security | N |
| 🟡 Unused | N |
| 🟡 Format | N |
| 🔵 Naming | N |

### Findings

[Grouped by severity, each with file location and recommendation]

### Generated Files
- `.env.example` — [created/updated]
- `env.ts` — [created/updated] (typed validation schema)

Auto-Fix

After identifying issues, automatically generate: (1) an updated .env.example with all missing variables added with placeholder values, (2) a typed env schema file using the configured validation library. Ask the user before overwriting existing files.

Reference

See [references/env-patterns.md](references/env-patterns.md) for T3 env setup details and common variable catalogs.

Source & license

This open-source skill is cataloged on AgentStack and links to its original source — we do not rehost the code.

• Author: Nembie
• Source: Nembie/claude-code-skills
• License: MIT

Install and usage instructions live in the source repository linked above.