Docker Image Full Reference Regex for Python

What this pattern does

This page provides a comprehensive, battle-tested regular expression for matching docker image full reference, 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 Full Reference
# ReDoS-safe | RegexVault — Dev & Systems > Docker

import re

docker_image_full_reference_pattern = re.compile(r'^(?:(?:[a-zA-Z0-9][a-zA-Z0-9\-._]*(?::[0-9]+)?)/)?(?:[a-z][a-z0-9\-._]*/)?[a-z][a-z0-9\-._]*(?::([a-zA-Z0-9][a-zA-Z0-9._\-]{0,127})|@(sha256:[a-fA-F0-9]{64}))?$')

def validate_docker_image_full_reference(value: str) -> bool:
    return bool(docker_image_full_reference_pattern.fullmatch(value))

# Example
print(validate_docker_image_full_reference("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

Group 1 = tag, group 2 = digest. Docker resolves bare names like 'nginx' to 'docker.io/library/nginx:latest'. Always specify the full reference in IaC and CI/CD pipelines.