Environment Variable Manager (env-manager)

Comprehensive environment variable validation, security scanning, and management for modern web applications.

Overview

The env-manager skill provides systematic environment variable management across local development, CI/CD pipelines, and deployment platforms. It prevents common issues like missing variables, exposed secrets, and framework-specific configuration errors.

Key Features:

• Framework-Aware Validation: Next.js, Vite, React, Node.js, Flask support

• Security-First: Never logs secrets, detects exposed credentials

• Platform Integration: Ready for Vercel, Railway, Heroku, and CI/CD

• Fast: Validates 1000 variables in 0.025s (80x faster than 2s target)

• Zero Dependencies: Pure Python, works anywhere

Why Use env-manager?

Common problems this solves:

• "Works on my machine, but not in production" (missing env vars)

• Accidentally exposing API keys in client-side code (NEXT_PUBLIC_ with secrets)

• Missing required variables during deployment

• Inconsistent .env files across team members

• No documentation of required environment variables

• Security vulnerabilities from exposed secrets

Quick Start

Installation

No installation needed! env-manager is a bundled skill in Claude MPM.

Requirements:

• Python 3.7+

• No external dependencies

5-Minute Quick Start

1. Validate your .env file

python3 scripts/validate_env.py .env

2. Check for framework-specific issues (Next.js example)

python3 scripts/validate_env.py .env --framework nextjs

3. Compare with .env.example to find missing vars

python3 scripts/validate_env.py .env --compare-with .env.example

4. Generate .env.example for documentation

python3 scripts/validate_env.py .env --generate-example .env.example

5. Get JSON output for CI/CD integration

python3 scripts/validate_env.py .env --json

That's it! Environment variables are now validated professionally.

Usage Examples

Basic Validation

Validate a .env file for structural issues:

python3 scripts/validate_env.py .env

What it checks:

• Valid key=value format

• No duplicate keys

• Proper naming conventions (UPPERCASE_WITH_UNDERSCORES)

• No empty values (unless explicitly allowed)

• Proper quoting for values with spaces

Example output:

✅ Validation successful!

• 15 variables validated
• 0 errors
• 0 warnings

Framework-Specific Validation

Next.js

Validate Next.js environment variables:

python3 scripts/validate_env.py .env.local --framework nextjs

Next.js-specific checks:

• NEXT_PUBLIC_* variables are client-exposed (warns if secrets detected)

• .env.local, .env.production, .env file hierarchy

• Detects secrets in client-side variables

Example:

.env.local

NEXT_PUBLIC_API_URL=https://api.example.com NEXT_PUBLIC_API_KEY=secret123 # ⚠️ WARNING: Secret in client-exposed variable! DATABASE_URL=postgresql://... # ✅ Server-side only

Vite

python3 scripts/validate_env.py .env --framework vite

Vite-specific checks:

• VITE_* variables are client-exposed

• Warns if secrets detected in VITE_ prefixed vars

React (Create React App)

python3 scripts/validate_env.py .env --framework react

React-specific checks:

• REACT_APP_* variables are client-exposed

• Warns if secrets in REACT_APP_ prefixed vars

Node.js/Express

python3 scripts/validate_env.py .env --framework nodejs

Node.js-specific checks:

• Common NODE_ENV, PORT, DATABASE_URL patterns

• Standard Node.js conventions

Flask/Python

python3 scripts/validate_env.py .env --framework flask

Flask-specific checks:

• FLASK_APP, FLASK_ENV variables

• SQLAlchemy DATABASE_URL format

Comparing with .env.example

Ensure your .env has all required variables:

python3 scripts/validate_env.py .env --compare-with .env.example

What it checks:

• All variables in .env.example exist in .env

• No extra undocumented variables in .env

Example output:

❌ Missing variables:

• DATABASE_URL (required in .env.example)
• STRIPE_SECRET_KEY (required in .env.example)

⚠️ Extra variables not in .env.example:

• DEBUG_MODE (consider adding to .env.example)

Perfect for:

• Onboarding new team members

• CI/CD validation

• Deployment pre-checks

Generating .env.example

Create documentation for your environment variables:

python3 scripts/validate_env.py .env --generate-example .env.example

What it does:

• Reads your .env file

• Sanitizes secret values (replaces with placeholders)

• Generates .env.example with safe defaults

Example:

Input: .env

DATABASE_URL=postgresql://user:pass@localhost/db # pragma: allowlist secret STRIPE_SECRET_KEY=sk_live_abc123xyz NEXT_PUBLIC_API_URL=https://api.example.com

Output: .env.example

DATABASE_URL=postgresql://user:password@localhost/dbname # pragma: allowlist secret STRIPE_SECRET_KEY=your_stripe_secret_key_here NEXT_PUBLIC_API_URL=https://api.example.com

Security note: env-manager detects common secret patterns and replaces them with safe placeholders.

CI/CD Integration

Get machine-readable JSON output for automated workflows:

python3 scripts/validate_env.py .env.example --strict --json

JSON output format:

{ "valid": true, "errors": [], "warnings": [], "stats": { "total_vars": 15, "errors": 0, "warnings": 0 } }

Exit codes:

• 0 : Validation passed

• 1 : Validation errors found

• 2 : Missing required file

• 3 : Warnings found (only in --strict mode)

GitHub Actions example:

name: Validate Environment Variables

on: [push, pull_request]

jobs: validate-env: runs-on: ubuntu-latest steps: - uses: actions/checkout@v3

  - name: Validate .env.example
    run: |
      python3 scripts/validate_env.py .env.example --strict --json
    working-directory: ./path/to/skill

  - name: Check for framework-specific issues
    run: |
      python3 scripts/validate_env.py .env.example --framework nextjs --json
    working-directory: ./path/to/skill

Strict Mode

Treat warnings as errors (useful for CI/CD):

python3 scripts/validate_env.py .env --strict

When to use:

• Pre-deployment validation

• CI/CD pipelines

• Release gates

• Team standard enforcement

Quiet Mode

Show only errors, suppress warnings:

python3 scripts/validate_env.py .env --quiet

When to use:

• You've already reviewed warnings

• Automated scripts that only care about errors

• Noisy environments where warnings are distracting

Supported Frameworks

Framework Prefix Client-Exposed Notes

Next.js NEXT_PUBLIC_*

Yes Auto-exposed in browser

Vite VITE_*

Yes Bundled into client code

React (CRA) REACT_APP_*

Yes Embedded in production build

Node.js N/A No Server-side only

Flask N/A No Server-side only

Security warning: Never put secrets in client-exposed variables (NEXT_PUBLIC_, VITE_, REACT_APP_). env-manager will warn you if it detects common secret patterns.

CLI Reference

Command Structure

python3 scripts/validate_env.py <file> [options]

Options

Option Description Example

--compare-with FILE

Compare with .env.example --compare-with .env.example

--framework {nextjs|vite|react|nodejs|flask|generic}

Framework-specific validation --framework nextjs

--strict

Treat warnings as errors --strict

--json

JSON output for automation --json

--quiet

Only show errors --quiet

--generate-example OUTPUT

Generate .env.example --generate-example .env.example

Exit Codes

Code Meaning When

0

Success No errors (warnings OK unless --strict)

1

Validation errors Structural issues, duplicates, etc.

2

File not found Specified .env file doesn't exist

3

Warnings in strict mode Warnings exist and --strict enabled

Common Use Cases

Scenario 1: New Developer Onboarding

New developer clones repo

git clone <repo> cd <project>

Copy example and fill in values

cp .env.example .env

Edit .env with actual values...

Validate setup

python3 scripts/validate_env.py .env --compare-with .env.example

If missing variables, fix them

Validation passes ✅

Scenario 2: Pre-Deployment Check

Before deploying to Vercel/Railway/Heroku

python3 scripts/validate_env.py .env.production --framework nextjs --strict

Fix any errors

Deploy with confidence ✅

Scenario 3: Security Audit

Check for accidentally exposed secrets

python3 scripts/validate_env.py .env.local --framework nextjs

Look for warnings like:

⚠️ NEXT_PUBLIC_STRIPE_SECRET: Contains potential secret in client-exposed variable

Scenario 4: Team Documentation

After adding new environment variable

echo "NEW_API_KEY=abc123" >> .env

Regenerate .env.example

python3 scripts/validate_env.py .env --generate-example .env.example

Commit updated .env.example

git add .env.example git commit -m "docs: add NEW_API_KEY to environment variables"

Scenario 5: CI/CD Quality Gate

In your CI pipeline

• name: Validate environment configuration run: | python3 scripts/validate_env.py .env.example --strict --json > validation.json

  Fail pipeline if validation fails

  if [ $? -ne 0 ]; then cat validation.json exit 1 fi

Performance

env-manager is designed for speed:

Benchmarks:

• Validates 1000 variables in 0.025s

• 80x faster than 2s target

• Zero external dependencies

• Minimal memory footprint

Why it matters:

• Fast feedback during development

• No CI/CD slowdown

• Works in resource-constrained environments

Security Notes

Critical security features:

• Never Logs Secrets: env-manager NEVER displays actual secret values in output

• Client-Exposure Detection: Warns when secrets are in NEXT_PUBLIC_, VITE_, REACT_APP_ variables

• Secret Sanitization: When generating .env.example, replaces secrets with safe placeholders

• No Network Calls: All validation is local, no data leaves your machine

Security-audited: This skill has undergone security review. See references/security.md for details.

Best practices:

• Never commit .env files with secrets

• Always use .env.example for documentation

• Use platform secret managers (Vercel, Railway, etc.) for production

• Validate before every deployment

• Run security scan regularly

Common Issues

"Missing equals sign" error

Cause: Line in .env doesn't have = separator

Fix:

❌ Bad

API_KEY

✅ Good

API_KEY=your_key_here

"Duplicate key" error

Cause: Same variable defined multiple times

Fix:

❌ Bad

API_KEY=value1 API_KEY=value2

✅ Good

API_KEY=value2

"Invalid variable name" warning

Cause: Variable name doesn't follow UPPERCASE_WITH_UNDERSCORES convention

Fix:

❌ Bad

apiKey=value api-key=value

✅ Good

API_KEY=value

"Potential secret in client-exposed variable" warning

Cause: NEXT_PUBLIC_, VITE_, or REACT_APP_ variable contains secret-like value

Fix:

❌ Bad (secret exposed to client!)

NEXT_PUBLIC_STRIPE_SECRET=sk_live_abc123

✅ Good (server-side only)

STRIPE_SECRET_KEY=sk_live_abc123 NEXT_PUBLIC_STRIPE_PUBLISHABLE=pk_live_xyz789

"Empty value" warning

Cause: Variable has no value

Fix:

❌ Bad

DATABASE_URL=

✅ Good (if optional, document it)

DATABASE_URL= # Optional, uses SQLite if not set

✅ Better

DATABASE_URL=postgresql://localhost/mydb

File not found error

Cause: Specified .env file doesn't exist

Fix:

Check file exists

ls -la .env

Or create it

touch .env

Troubleshooting

Validation passes locally but fails in CI

Check:

• Line endings (CRLF vs LF)

• File encoding (UTF-8 expected)

• File permissions

• Python version (3.7+ required)

Warnings about client-exposed variables

This is intentional! env-manager is warning you that variables like NEXT_PUBLIC_API_KEY will be visible in the browser.

Options:

• Move secret to server-side variable (remove NEXT_PUBLIC_ prefix)

• Use public/publishable keys only in client-exposed variables

• If truly not a secret, ignore the warning

.env.example generation replaces too much

env-manager is conservative about secrets. If it over-sanitizes:

• Manually edit .env.example after generation

• Use specific placeholder values in .env that won't trigger sanitization

Advanced Usage

Custom Validation Patterns

See references/validation.md for advanced validation patterns.

Platform-Specific Deployment

See references/synchronization.md for Vercel, Railway, Heroku integration patterns.

Framework-Specific Guides

See references/frameworks.md for comprehensive framework guides.

Related Documentation

• Validation Reference: Complete validation workflows and checks

• Security Reference: Secret scanning and security patterns

• Synchronization Reference: Platform sync patterns (coming soon)

• Frameworks Reference: Framework-specific patterns and conventions

• Troubleshooting Guide: Common issues and solutions

Integration with Claude MPM

env-manager is a bundled skill in Claude MPM. Agents can use it for:

• Pre-deployment validation

• Security scanning

• Environment setup verification

• Documentation generation

See INTEGRATION.md for agent integration patterns.

Contributing

env-manager follows Claude MPM contribution guidelines:

• Run make lint-fix during development

• Run make quality before commits

• Add tests for new features (85%+ coverage required)

• Update documentation

See CONTRIBUTING.md for details.

License

MIT License - Part of Claude MPM project

Support

• Issues: Report bugs via GitHub Issues

• Documentation: See references/ directory

• Examples: See examples/ directory

• Integration: See INTEGRATION.md

Version: 1.0.0 Status: Stable, Security-Audited Test Coverage: 85%+ Performance: 80x faster than target