# Docker Image Tag Validator

Validate Docker image names and tags according to Docker naming conventions

> Canonical page: https://elysiatools.com/en/tools/docker-image-tag-validator

- **Category:** Validation

- **Keywords:** docker, image, tag, container, validator, registry, repository, digest

## Overview

The Docker Image Tag Validator checks if a given Docker image reference, including name and tag, adheres to Docker's official naming conventions. It helps ensure that image references are correctly formatted for use in container registries and deployments.

## Inputs

- **Docker Image Reference** (text): Enter image reference (e.g., nginx:latest, docker.io/library/nginx:alpine)...

## When to use

- When writing or reviewing Dockerfiles to ensure base image references are valid.
- Before pushing images to a container registry to avoid rejection due to naming issues.
- When debugging deployment failures that might be caused by malformed image references.

## How it works

- Enter the Docker image reference, such as 'nginx:latest' or 'docker.io/library/ubuntu:20.04'.
- The tool parses the reference into its components: registry, repository, tag, or digest.
- It validates each component against Docker's official naming rules and conventions.
- Returns a validation result indicating success or detailing any errors found.

## Use cases

- Integrating into CI/CD pipelines to automatically validate image tags before deployment.
- Manually checking image references during development to catch errors early.
- Auditing scripts or configuration files that contain Docker image references for correctness.

## Frequently asked questions

### What is a Docker image reference?

A Docker image reference is a string that identifies a Docker image, typically in the format [registry/]repository[:tag] or [registry/]repository[@digest].

### What naming rules does Docker enforce?

Repository names must be lowercase, can include dots, dashes, and underscores, and tags must consist of valid ASCII characters without spaces.

### Can this tool validate image digests?

Yes, it can check references that include digests, such as 'nginx@sha256:abc123...'.

### Are there length limits for image names?

Docker imposes length limits on repository names and tags; the tool verifies compliance with these limits.

### What should I do if validation fails?

Review the error message provided by the tool to identify and correct the invalid part of the image reference.

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## Samples

- [Docker Image Tag Samples](https://elysiatools.com/en/samples/docker-image-tag): Collection of Docker image references with various registries, repositories, tags, and digests
- [Web Image Processing Python Samples](https://elysiatools.com/en/samples/web-image-processing-python): Web Python image processing examples using PIL/Pillow including reading, saving, resizing, and format conversion
- [Android Image Processing Java Samples](https://elysiatools.com/en/samples/android-image-processing-java): Android Java image processing examples including reading/saving images, scaling, and format conversion
- [Android Image Processing Kotlin Samples](https://elysiatools.com/en/samples/android-image-processing-kotlin): Android Kotlin image processing examples including reading/saving images, scaling, and format conversion

## Related content

- [Network Infrastructure Identifier Format Checks](https://elysiatools.com/en/hubs/network-infrastructure-identifier-format-checks): Check IPv4 and IPv6 addresses, CIDR values, MAC addresses, AWS ARNs, and Docker image references before downstream processing, while keeping format evidence separate from reachability, ownership, permissions, and image availability.