Docker Image Name (Official/Simple) Regex for Python

What this pattern does

This page provides a lightweight, single-purpose regular expression for matching docker image name (official/simple), 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 Image Name (Official/Simple)
# ReDoS-safe | RegexVault — Dev & Systems > Docker

import re

docker_image_name_officialsimple_pattern = re.compile(r'^[a-z][a-z0-9\-._]{0,127}$')

def validate_docker_image_name_officialsimple(value: str) -> bool:
    return bool(docker_image_name_officialsimple_pattern.fullmatch(value))

# Example
print(validate_docker_image_name_officialsimple("nginx"))  # 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

Official images are lowercase. The maximum total image reference length is 255 chars. Underscores and dots are valid but hyphens cannot be the first character.