Docker Image Tag Regex Pattern

Match Docker image names with tags

•

Difficulty

Language

none

Flags

// Regular Expression

/^[a-z0-9]+(?:[._-][a-z0-9]+)*(?:/[a-z0-9]+(?:[._-][a-z0-9]+)*)*(?::[a-zA-Z0-9._-]+)?$/

Live Regex Tester

Pattern

Flags

Test String

Pattern Breakdown

^[a-z0-9]+(?:[._-][a-z0-9]+)*(?:/[a-z0-9]+(?:[._-][a-z0-9]+)*)*(?::[a-zA-Z0-9._-]+)?$

Character class [ ]

Group ( )

Quantifier { }

Anchor ^ $

Repetition * + ?

Escape \

Alternation |

Any char .

Code Examples

JavaScript

const regex = /^[a-z0-9]+(?:[._-][a-z0-9]+)*(?:/[a-z0-9]+(?:[._-][a-z0-9]+)*)*(?::[a-zA-Z0-9._-]+)?$/undefined;
const test = "undefined";
console.log(regex.test(test)); // true

// Extract matches
const matches = test.match(regex);
console.log(matches);

Python

import re

pattern = r'^[a-z0-9]+(?:[._-][a-z0-9]+)*(?:/[a-z0-9]+(?:[._-][a-z0-9]+)*)*(?::[a-zA-Z0-9._-]+)?$'
test = "undefined"
match = re.search(pattern, test)
print(match)  # Found!

Go

package main

import (
    "fmt"
    "regexp"
)

func main() {
    re := regexp.MustCompile(`^[a-z0-9]+(?:[._-][a-z0-9]+)*(?:/[a-z0-9]+(?:[._-][a-z0-9]+)*)*(?::[a-zA-Z0-9._-]+)?$`)
    fmt.Println(re.MatchString("undefined")) // true
}

Common Use Cases

Match Examples

Input	Result
	Match
	No Match

About the Docker Image Tag Regex

Match Docker image names with tags

Regular expressions (regex) are powerful pattern matching tools used across virtually all programming languages. The docker image tag pattern. It works in all major programming languages.

When using this regex, always consider edge cases and test thoroughly with real-world data. Use the interactive tester above to validate the pattern against your specific inputs before deploying to production.

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Frequently Asked Questions

What is the Docker Image Tag regex pattern?

Match Docker image names with tags

How do I use the Docker Image Tag regex?

Use the pattern /^[a-z0-9]+(?:[._-][a-z0-9]+)*(?:/[a-z0-9]+(?:[._-][a-z0-9]+)*)*(?::[a-zA-Z0-9._-]+)?$/undefined in your code. In JavaScript: new RegExp('^[a-z0-9]+(?:[._-][a-z0-9]+)*(?:/[a-z0-9]+(?:[._-][a-z0-9]+)*)*(?::[a-zA-Z0-9._-]+)?$', 'undefined'). Test it above with your own input.

What does this Docker Image Tag regex match?

Is the Docker Image Tag regex beginner-friendly?

This pattern is rated Intermediate. It uses advanced features like lookaheads, backreferences, or complex alternation.

What languages support the Docker Image Tag regex?

This pattern works in all major programming languages including JavaScript, Python, Java, C#, Go, Ruby, PHP, and more. Syntax may vary slightly between regex engines.

Can I modify the Docker Image Tag regex for my use case?

Yes! Use the interactive tester above to modify the pattern and test with your own data. Common modifications include making it case-insensitive (add 'i' flag), matching globally (add 'g' flag), or adjusting character classes.