How to create basic images by docker

Creating a Docker base image involves the following steps: Create a base file system, including the necessary files and directories. Install the required packages. Create users and groups (optional). Set the working directory (optional). Configure environment variables (optional). Submit the image to save your changes.

How to create a Docker image

Creating a Docker base image is a simple process that allows you to build more complex images on top of your own custom images. Here are the steps to create a basic image:

Step 1: Create the base file system

First, you need to create a base file system that will contain files and directories from your base image. You can create from scratch or start from an existing image using the Dockerfile FROM command.

For example, the following Dockerfile will create a basic image based on the Ubuntu 20.04 operating system:

 <code>FROM ubuntu:20.04</code>

Step 2: Install the necessary software

Next, you need to install any packages you need for the base image. You can do this using the Dockerfile RUN command.

For example, the following RUN command will install Python 3 and Pip package manager:

 <code>RUN apt-get update && apt-get install -y python3-pip</code>

Step 3: Create Users and Groups (optional)

If you need to create users and groups in the base image, you can use the USER and GROUP Dockerfile directives.

For example, the following directive creates a user named "appuser" and adds it to a group named "appgroup":

 <code>USER appuser GROUP appgroup</code>

Step 4: Set the working directory (optional)

If you want to set the working directory of the base image to a specific directory, you can use the WORKDIR Dockerfile directive.

For example, the following directive will set the working directory to the "/app" directory:

 <code>WORKDIR /app</code>

Step 5: Configure environment variables (optional)

If you need to set environment variables, you can use the ENV Dockerfile directive.

For example, the following directive sets the value of the environment variable named "MY_VARIABLE" to "Hello World":

 <code>ENV MY_VARIABLE="Hello World"</code>

Step 6: Submit the mirror

After completing the base image, you can submit it to your local Docker repository using the following command:

 <code>docker commit -m "我的基础镜像"  </code>

in:

• is the ID of the underlying container that creates the image.
• is the name you want to assign to the base image.

Once the image is submitted, you can find it in the Docker repository and use it as the basis for building more complex images.

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