10 Docker Image Naming Convention Best Practices

Docker images are the building blocks of containerized applications. As such, it is important to have a consistent naming convention for your Docker images. This will help you keep track of your images and ensure that they are properly identified and managed.

In this article, we will discuss 10 best practices for naming Docker images. We will also discuss how to use tags to further organize your images and make them easier to find. By following these best practices, you can ensure that your Docker images are properly identified and managed.

1. Use a reverse domain name

Using a reverse domain name helps to ensure that your images are unique and easily identifiable. It also makes it easier for other users to find and use your images, as they can quickly identify the source of the image by looking at its name. Additionally, using a reverse domain name allows you to group related images together, making them easier to manage.

2. Keep the image name short, but meaningful

When you’re working with Docker images, it’s important to be able to quickly identify what the image contains. If your image name is too long or doesn’t provide enough information about its contents, it can be difficult to determine which image you need for a particular task. Keeping the image name short and meaningful helps ensure that you can easily find the right image when you need it.

It’s also important to use consistent naming conventions across all of your images. This will help keep your images organized and make them easier to locate in the future. For example, if you have multiple versions of an application, you could include the version number in the image name so that you know exactly which version you are using.

3. Use kebab-case for multi-word names

Kebab-case is a type of naming convention that uses hyphens to separate words in a name. This makes it easier for developers to read and understand the image names, as well as making them more consistent across different systems. It also helps avoid potential conflicts with other images or services that may have similar names.

Using kebab-case for multi-word docker image names can help ensure consistency and clarity when working with multiple images. This will make it easier for developers to quickly identify which image they need to use, and reduce the chances of errors due to miscommunication.

4. Use lowercase only

Using lowercase only helps to ensure that the image name is consistent across different operating systems. This makes it easier for developers and users to find, share, and use images without worrying about case sensitivity issues. Additionally, using all lowercase letters can help make the image names more readable and easier to remember.

Finally, using lowercase only also helps to avoid potential conflicts with other naming conventions used by other software or services. For example, some cloud providers may have their own naming conventions which could conflict with a docker image name if it contains uppercase characters.

5. Don’t use underscores ( _ ) or uppercase letters

Using underscores or uppercase letters can cause confusion when trying to reference the image. For example, if you have an image named “My_Image” and another one called “myimage”, it could be difficult to differentiate between them. This is especially true if you are using a command line interface (CLI) to manage your images.

It’s also important to note that some registries may not support underscores or uppercase letters in their naming conventions. Therefore, it’s best to stick with lowercase letters and hyphens (-) for all of your docker image names.

6. Avoid source control management identifiers in image tags

When you use source control management identifiers in image tags, it can lead to confusion and errors when trying to identify the correct version of an image. This is because these identifiers are often specific to a particular repository or branch, which means they won’t be consistent across different repositories or branches.

Instead, it’s best practice to use semantic versioning for your docker images. This will ensure that each tag is unique and easily identifiable, regardless of where it was created. Additionally, using semantic versioning makes it easier to track changes over time and quickly identify any issues with a particular version.

7. Use immutable tags for production images

Immutable tags are permanent and unchanging, meaning that once you tag an image with a specific version number, it will never change. This is important for production images because it ensures that the same exact image is always used in production, which helps to reduce errors and ensure consistency across deployments.

Using immutable tags also makes it easier to roll back changes if something goes wrong. If you use mutable tags (which can be changed at any time), then it’s difficult to know exactly what version of the image was deployed when something went wrong. With immutable tags, you can easily identify the exact version of the image that was deployed and quickly roll back to it.

8. Use latest tag for your CI/CD pipeline

The latest tag is a special tag that always points to the most recent version of your image. This makes it easy for you to keep track of which version of your image is currently in production, and also allows you to quickly roll back to an earlier version if needed.

Using the latest tag also ensures that any changes made to your image are immediately available to your CI/CD pipeline, so you don’t have to manually update the tag each time you make a change. This saves time and reduces the risk of errors.

9. Tag by functionality not by release number

When you tag an image by release number, it can be difficult to determine what the image contains. For example, if you have a docker image tagged as “1.0”, does that mean it’s the first version of the application or the tenth? By tagging images with functionality instead of release numbers, you make it easier for users to understand what the image contains and how it should be used.

For instance, if you have an image containing a web server, you could name it something like “webserver-v1” instead of just “1.0”. This makes it much clearer to users what the image contains and how they should use it.

10. Use semantic versioning

Semantic versioning is a way of labeling your images with meaningful information about the content and changes that have been made. This helps you keep track of different versions of an image, as well as quickly identify which one contains the most up-to-date code or configuration.

For example, if you’re using semantic versioning for your docker images, you might name them something like “myapp:1.2.3”. The first number (1) indicates a major change, the second number (2) indicates minor changes, and the third number (3) indicates patch updates. This makes it easy to tell at a glance which version of the image has the latest features and bug fixes.