envlint 0.1.0

Validate .env files against a schema. Catch missing and invalid environment variables before runtime.

envlint

Language-agnostic .env validation. One schema, any stack.

Validate your .env files in CI before your app even starts. Works with Python, Node, Go, Rust, Ruby—any language that uses environment variables.

Why envlint?

Existing solutions like pydantic-settings (Python) or envalid (JavaScript) only work within their own language. You need to run your app to validate your config.

envlint is different:

• Language-agnostic — Define your schema once, validate from any CI pipeline
• Catches issues at build time — Before your app crashes in production
• No code changes — Just a YAML schema and a CLI command
• No SDK or runtime dependency — Your app doesn't need to know envlint exists

# Your app crashes in production because...
KeyError: 'DATABASE_URL'

# Or silently uses wrong values...
API_URL=htpp://api.example.com  # typo in scheme
PORT=not_a_number               # string where int expected

envlint catches these in CI, not production.

Installation

pip install envlint

Quick Start

1. Create a schema file (.env.schema):

DATABASE_URL:
  type: url
  required: true

API_KEY:
  type: string
  required: true
  pattern: "^sk_[a-zA-Z0-9]{32}$"

PORT:
  type: port
  required: false
  default: "3000"

DEBUG:
  type: bool
  required: false

2. Run envlint:

envlint check

3. See results:

┌─────────────────────────────────────────────────┐
│ envlint                                        │
├─────────────────────────────────────────────────┤
│ ✓ All 4 variables validated successfully       │
└─────────────────────────────────────────────────┘

Or if there are errors:

┌─────────────────────────────────────────────────┐
│ Errors                                          │
├──────────────┬────────────────────┬─────────────┤
│ Variable     │ Error              │ Value       │
├──────────────┼────────────────────┼─────────────┤
│ DATABASE_URL │ required variable  │ -           │
│              │ is missing         │             │
│ API_KEY      │ must match pattern │ invalid_key │
│ PORT         │ must be a port     │ abc         │
│              │ number (0-65535)   │             │
└──────────────┴────────────────────┴─────────────┘

Exit code is 1 on errors, 0 on success. Perfect for CI/CD.

Schema Format

Supported Types

Type	Description	Example
string	Any string (default)	my-value
int	Integer	42
float	Decimal number	3.14
bool	Boolean (true/false, 1/0, yes/no)	true
url	Valid URL with scheme	https://api.example.com
email	Email address	[e-mail]
port	Port number (0-65535)	8080
path	File path	/var/log/app.log

Full Schema Options

MY_VARIABLE:
  type: string          # Type (see above)
  required: true        # Is this variable required?
  default: "value"      # Default value if missing
  pattern: "^[A-Z]+$"   # Regex pattern to match
  description: "..."    # Documentation
  choices:              # Allowed values
    - option1
    - option2
  min: 0                # Minimum (for numeric types)
  max: 100              # Maximum (for numeric types)

Shorthand Syntax

For simple variables, use shorthand:

# These are equivalent:
API_KEY: string
API_KEY:
  type: string
  required: true

# Just the name = required string
SECRET:

CLI Usage

# Basic validation
envlint check

# Specify files
envlint check --env .env.production --schema env.schema.yml

# Include system environment variables
envlint check --system

# Strict mode (fail on undefined variables)
envlint check --strict

# Verbose output (show warnings)
envlint check --verbose

# Quiet mode (only output on error)
envlint check --quiet

# Generate schema from existing .env
envlint init --from-env .env

# Create template schema
envlint init

CI/CD Integration

GitHub Actions

- name: Validate environment
  run: |
    pip install envlint
    envlint check --env .env.example --schema .env.schema

Pre-commit Hook

# .pre-commit-config.yaml
repos:
  - repo: local
    hooks:
      - id: envlint
        name: envlint
        entry: envlint check
        language: system
        pass_filenames: false

Docker Build

FROM python:3.11
RUN pip install envlint
COPY .env.schema .
COPY .env .
RUN envlint check
# ... rest of build

License

GPL v3

Contributing

Contributions welcome! Please read CONTRIBUTING.md first.