How to merge two Docker images

Docker is a lightweight containerization technology widely used in modern application development. It allows developers to deploy applications across production environments, including cloud, physical and virtual machine environments. Docker images are a core component of Docker technology. Images are portable containers that can be used to build and deploy applications. This article will introduce how to merge two Docker images.

1. Docker Image Overview

Before introducing the Docker image merging operation, you first need to understand the basic concepts of Docker images.

Docker image is a template that contains information such as running environment, applications, libraries and dependencies. They are portable, lightweight, repeatable containers that can be used to build and deploy applications. Docker images are built from Dockerfile files, which specify the application's running environment and dependencies.

2. Docker image merging

Docker image merging is the process of merging two or more Docker images into a new image. When merging, merge all files and metadata from all images into a new Docker image.

Generally, reasons for merging two Docker images into a new image include:

• Merge different versions of an application.
• Merge applications from different sources.
• is used to update existing images.
• To create a customized Docker image.

Before you start merging Docker images, make sure the Docker engine is installed and started.

3. Merge Docker image steps

The following are the steps to merge two Docker images into a new image:

Step 1: Pull image

First, you need to Pull two images from Docker Hub, such as nginx and alpine:

docker pull nginx
docker pull alpine

Step 2: Create a new image container

Next, you need to create a new image Container, which will contain all files and metadata from both images. In this example, a new container named "merged-image" will be created:

docker create --name merged-image nginx

Step 3: Import a container into the new image container

Next, you need to add the second Import the contents of an image into a new container:

docker export $(docker create -ti --name temp alpine /bin/sh)
  | docker import - merged-image

• docker create -ti --name temp alpine /bin/sh: Execute a Shell terminal in the temporary container.
• docker export: Pack the container's file system into a tar file and output it to stdout.
• docker import - merged-image: Import the tar file into a new image (named merged-image).

Step 4: Start the new image container

Now, you can use the docker run command to start the new merged image container:

docker run --name merged-container -p 8080:80 --rm merged-image

In the above command, add The container's port is mapped to the host's port 8080 and the container is run. In this example, nginx server is used as HTTP server to display the merged files in this container.

4. Summary

Merging two Docker images can be used for many different purposes, such as merging different versions of an application, merging applications from different sources, merging an existing Mirrors provide updates, etc.

In this article, we introduce the steps to merge two Docker images into a new image. In this process, you need to pull two Docker images, create a new image container, and merge all files and metadata in the two images into a new Docker image.

The merging of Docker images is an important concept in Docker. Mastering this technology can help developers handle applications in Docker environments more efficiently.

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