Where does the docker image exist?

Docker is a platform that makes it easy to package, publish, and manage applications. In Docker, the image is a very important concept. It actually contains all the code and dependencies of the application, so it is also called a "container image."

So, where do Docker images actually exist?

First of all, you need to understand that in Docker, images and containers are two different concepts. The image is a read-only file system, while the container is a writable layer created on the basis of the image, and is an instance running on the image. Therefore, each container needs to be started based on an image.

So, where does the image exist in Docker? In fact, Docker images exist in the Docker Registry, and the Docker Registry can store public or private Docker images.

Docker officially provides a public Docker image warehouse called Docker Hub. On Docker Hub, you can find a variety of different images, both official and community-created. In addition to Docker Hub, there are other Docker Registries, such as Google Container Registry, Amazon Elastic Container Registry, etc.

When pulling an image from the Docker Registry through the docker pull command, it actually obtains the entire contents of the image remotely and saves it to the Docker image library on the local host. By default, when executing the docker run command, Docker will first check whether the image already exists on the local host. If not, it will pull the image from the Docker Registry and create a container instance on the host.

In addition, Docker also supports the creation of a private Docker Registry. You can build a private Docker image warehouse on the local host to store the images you build. You can also access other Docker images in the private warehouse. .

To summarize, in Docker, the image actually exists in the Docker Registry. When the image is obtained from the Registry, it will be saved to the Docker image library of the local host. At the same time, you can also create a private Docker Registry to store the images you build. Understanding these concepts and principles will allow you to better understand and use Docker, and manage and deploy applications more efficiently.

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