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This article mainly introduces the relevant knowledge of how to use latest tags in Docker, the content is detailed and easy to understand, the operation is simple and fast, and has a certain reference value, I believe you will have something to gain after reading this Docker article on how to use latest tags, let's take a look at it.

There are usually two ways to label the image: using the docker tag command or passing parameters with-t when docker build is executed. In both cases, the parameter is usually in the form of repository_name:tag_name, for example: docker tag myrepo:mytag. If the repository is uploaded to Docker Hub, the name of the repository is prefixed with a Docker Hub user name and a slash, for example: amouat/myrepo:mytag. If you do not add the parameters in the tag section, for example, docker tag myrepo:1.0 myrepo,Docker will automatically tag it with latest. You may already be familiar with the above content, but in fact, it is only this point of content, and there is nothing magical about it.

You cannot assume that the image is the latest image in the repository just because its label is latest. Only as agreed by the owner of this repository, the image with the latest tag must be the latest image. For example, I can easily turn an outdated image into an image with a latest tag, such as:

The image with the latest tag here is the same as the version 0.9, both two weeks ago, while the 1.0 image is a minute ago.

Why this label puzzles many people is actually easier to understand. Does the sentence 'just pull the latest image'' mean to get the image with the latest tag or the latest image? Are the two the same? Are they the latest images in the repository? Is it the latest stable version image or the latest development version image?

To make matters worse, many people seem to think that the latest tag will be updated automatically, which means that if I get an image with a latest tag, Docker will check to see if it is the latest version before each run. This is absolutely not the case, just like other tags, you need to manually decide Docker to get the latest version of the image.

The confusion is more than that. What happens if I docker pull an image from the repository without specifying a label? If you think you will get all the images, then you are wrong, it will only get the one with the latest tag. If you need to get all the images, you need to add the-a flag. What happens if you perform a pull operation in the repository without a latest tag? As follows:

$docker pull amouat/myrepoPulling repository amouat/myrepo2015/01/21 12:04:06 Tag latest not found in repository amouat/myrepo

Unsurprisingly, Docker gave an error message. But I don't think you know what's going on here. An even more annoying thing is that the latest tag hides other tags, assuming you want to download a debian image with the latest tag. Which is its version?

$docker images debianREPOSITORY TAG IMAGE ID CREATED VIRTUAL SIZEdebian latest 4d6ce913b130 4 days ago 84.98 MB

Uh, I don't know. Actually, it's version 7.8 wheezy.

I think Docker should take all the tags with it when downloading the image, but I don't know why it didn't. The current situation is that users can have different versions of the same image because the server is marked with tags. For example, if both wheezy and latest are updated on Hub, and I only get the updated wheezy version of debian, then although they can be distinguished on Hub, my wheezy tag will be newer than the local latest tag.

This is the end of the article on "how to use latest tags in Docker". Thank you for reading! I believe that everyone has a certain understanding of the knowledge of "how to use latest tags in Docker". If you want to learn more, you are welcome to follow the industry information channel.

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