Docker Image Digest (SHA256) Regex for Python

What this pattern does

This page provides a lightweight, single-purpose regular expression for matching docker image digest (sha256), 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 Digest (SHA256)
# ReDoS-safe | RegexVault — Dev & Systems > Docker

import re

docker_image_digest_sha256_pattern = re.compile(r'^sha256:[a-fA-F0-9]{64}$')

def validate_docker_image_digest_sha256(value: str) -> bool:
    return bool(docker_image_digest_sha256_pattern.fullmatch(value))

# Example
print(validate_docker_image_digest_sha256("sha256:a3ed95caeb02ffe68cdd9fd84406680ae93d633cb16422d00e8a7c22955b46d4"))  # 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

64 hex characters = 256 bits = SHA-256 output. The sha256: prefix is mandatory for algorithm agility. Digest pinning provides immutable image references.