Docker Image Name (Official/Simple) Regex for PHP

What this pattern does

This page provides a lightweight, single-purpose regular expression for matching docker image name (official/simple), ported and verified for PHP. A rigorously tested regex reduces debugging time and protects your application from edge-case failures. The snippet below is ready to drop into your PHP project — whether you're validating in a Laravel validator, a WordPress plugin, or a standalone PHP script.

Php Implementation

<?php
// Docker Image Name (Official/Simple)
// ReDoS-safe | RegexVault — Dev & Systems > Docker

define('DOCKER_IMAGE_NAME_OFFICIALSIMPLE_PATTERN', '/^[a-z][a-z0-9\-._]{0,127}$/');

function validate_docker_image_name_officialsimple(string $input): bool {
    return (bool) preg_match(DOCKER_IMAGE_NAME_OFFICIALSIMPLE_PATTERN, $input);
}

// Example
var_dump(validate_docker_image_name_officialsimple("nginx")); // bool(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 PHP developers because especially relevant in PHP where PCRE backtracking limits can trigger silent failures on malicious input. 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.