Docker Environment Variable Assignment Regex for Python

What this pattern does

This page provides a well-structured, multi-part regular expression for matching docker environment variable assignment, ported and verified for Python. A rigorously tested regex reduces debugging time and protects your application from edge-case failures. The snippet below is ready to drop into your Python project — whether you're validating in a Django view, a FastAPI endpoint, or a standalone data processing script.

Python Implementation

# Docker Environment Variable Assignment
# ReDoS-safe | RegexVault — Dev & Systems > Docker

import re

docker_environment_variable_assignment_pattern = re.compile(r'^([a-zA-Z_][a-zA-Z0-9_]{0,255})(?:=([^\x00-\x1F\x7F]*))?$')

def validate_docker_environment_variable_assignment(value: str) -> bool:
    return bool(docker_environment_variable_assignment_pattern.fullmatch(value))

# Example
print(validate_docker_environment_variable_assignment("NODE_ENV=production"))  # True

Test Cases

When to use this pattern

This pattern is drawn from the Dev & Systems > Docker category and carries a ReDoS-safe certification. That matters for Python developers because particularly important in Python web servers where CPU-bound regex operations can stall concurrent request handling. RegexVault audits patterns against known backtracking attack vectors, ensuring you have the necessary context before using this regex in a high-stakes production environment.

Common Pitfalls

Technical Notes

Variable names must start with a letter or underscore. A bare KEY without = passes the variable from the host environment. Capture group 1 = key, group 2 = value (optional).