What does the docker image contain?

Docker images contain the following elements: file system layer (root file system, layer), metadata (Manifest file, configuration, tags), network settings (IP address, port mapping), users and groups (user ID , group ID), command (entry point, CMD).

What the Docker image contains

A Docker image is a lightweight, retrievable image that contains software and all its dependencies. Execute package. It provides everything you need to deploy and run applications in any environment. Specifically, a Docker image contains the following elements:

1. File system layer

• Root file system: Application runtime Required root file system image, including binaries, libraries, and configuration files.
• Layers: Separate file system layers that can be accumulated in the image, each layer containing incremental changes to the root file system. This allows images to be stored and updated efficiently.

2. Metadata

• JSON file: Manifest file describing metadata such as image content, size, and tags .
• Configuration: Configuration file that specifies the container's running configuration, such as entry points, environment variables, and volumes.
• Tags: Metadata key-value pairs used to organize and identify images.

3. Network settings

• IP address: The IP address assigned to the container.
• Port mapping: Mapping of external ports exposed inside the container to internal ports.

4. Users and groups

• User ID and group ID:Specify the user and group under which the process in the container runs .

5. Command

• Entry point: Command executed when the container starts.
• CMD: Default parameters for the entry point.

Docker images may also contain other content, such as custom scripts, data, and documentation. These elements provide additional functionality and flexibility, allowing users to tailor the image to specific needs.

The above is the detailed content of What does the docker image contain?. For more information, please follow other related articles on the PHP Chinese website!