Scanning a Python Project

Learn to detect environment variables in a Python application.

Time: 10 minutes

Prerequisites

Jnkn installed (pip install jnkn[full])
A Python project (or use our example)

Setup

If you don't have a project, create a sample:

mkdir jnkn-tutorial && cd jnkn-tutorial

Create app/config.py:

import os
from pydantic_settings import BaseSettings

class Settings(BaseSettings):
    database_url: str
    api_key: str
    debug: bool = False

    class Config:
        env_prefix = "APP_"

settings = Settings()

# Also using direct env access
REDIS_URL = os.getenv("REDIS_URL", "redis://localhost:6379")
LOG_LEVEL = os.environ.get("LOG_LEVEL", "INFO")

Create app/main.py:

from config import settings, REDIS_URL
import os

def get_db_connection():
    return connect(os.getenv("DATABASE_URL"))  # Different from settings!

def get_cache():
    return Redis.from_url(REDIS_URL)

Scan

jnkn init
jnkn scan

Output:

🔍 Scanning /path/to/jnkn-tutorial
📁 Found 2 Python files
✅ Parsed 8 nodes, 6 edges

Detected Environment Variables:
  env:APP_DATABASE_URL     (pydantic_settings)
  env:APP_API_KEY          (pydantic_settings)  
  env:APP_DEBUG            (pydantic_settings)
  env:REDIS_URL            (os.getenv)
  env:LOG_LEVEL            (os.environ.get)
  env:DATABASE_URL         (os.getenv)

Understanding the Output

Jnkn detected 6 environment variables from multiple patterns:

Variable	Source	Pattern
`APP_DATABASE_URL`	Pydantic Settings	`env_prefix + field_name`
`APP_API_KEY`	Pydantic Settings	`env_prefix + field_name`
`APP_DEBUG`	Pydantic Settings	`env_prefix + field_name`
`REDIS_URL`	Direct access	`os.getenv()`
`LOG_LEVEL`	Direct access	`os.environ.get()`
`DATABASE_URL`	Direct access	`os.getenv()`

Potential Bug Detected

Notice DATABASE_URL and APP_DATABASE_URL — these might be the same intent but different names. Jnkn helps you spot these inconsistencies.

View the Graph

jnkn stats

📊 Graph Statistics
═══════════════════════════════════
Nodes by Type:
  code_file:    2
  env_var:      6

Edges by Type:
  reads:        6

Explore Dependencies

Which files read REDIS_URL?

jnkn blast env:REDIS_URL

{
  "source": "env:REDIS_URL",
  "impacted": ["file://app/config.py"],
  "total_impacted": 1
}

Supported Python Patterns

Jnkn detects these patterns automatically:

Pattern	Example
`os.getenv()`	`os.getenv("VAR")`
`os.environ.get()`	`os.environ.get("VAR")`
`os.environ[]`	`os.environ["VAR"]`
Pydantic Settings	`class Config(BaseSettings)`
Pydantic Field	`Field(env="VAR")`
Click/Typer	`@click.option(envvar="VAR")`
django-environ	`env.str("VAR")`

See Python Patterns Reference for the full list.