Prevent tags from being overwritten

By default, users can push the same tag multiple times to a repository, thus overwriting the older versions of the tag. This can however lead to problems if a user pushes an image with the same tag name but different functionality. Also, when images are overwritten, it can be difficult to determine which build originally generated the image.

To prevent tags from being overwritten, you can configure a repository to be immutable. Once configured, MSR will not allow another image with the same tag to be pushed to the repository.


Enabling tag immutability disables repository tag limits.

Make tags immutable

You can enable tag immutability when creating a new repository or at a later time.

To enable tag immutability when creating a new repository:

  1. Log in to the MSR web UI.

  2. Follow the steps in Create a repository.

  3. On the new repository creation page, click Show advanced settings.

  4. Under Immutability, select On.

To enable tag immutability on an existing repository:

  1. Log in to the MSR web UI.

  2. In the left-side navigation panel, select Repositories.

  3. Select the relevant repository and navigate to the Settings tab.

  4. In the General section under Immutability, select On.

Once tag immutability is enabled, MSR will return an error message such as the following when you try to push a tag that already exists:

docker push
unknown: tag=latest cannot be overwritten because is an immutable repository