Docker image production steps

With the rise of cloud computing and containerization technology, Docker has become one of the most popular containerization technologies today. Compared with traditional virtualization technology, Docker containers are more lightweight, convenient, fast, flexible and portable. The Docker image is the basis of the Docker container and one of the core components. Therefore, understanding the production and use of Docker images is very important for learning and applying Docker container technology. This article will introduce the basic concepts and steps of Docker images to help readers better understand and master the use of Docker images.

1. Basic concepts of Docker image

1. Docker image: Docker image is a lightweight, independent, executable software package that contains what is needed to run a Docker container All configuration information and dependency files. Docker images can also be packaged, distributed and shared. When the Docker container is running, Docker will create a Docker container running instance based on the Docker image. There are many official and community-contributed Docker images on Docker Hub, and you can also make your own.
2. Dockerfile: Dockerfile is a text file that can contain a series of commands and instructions to automatically create a Docker image. Dockerfile can define the basic components and configuration of the Docker image so that the Docker image can obtain a specific environment when it is created.
3. Docker Hub: Docker Hub is the official image warehouse of Docker. It allows developers to upload their own images to Docker Hub storage and share them with the global Docker community. They can also download images shared by others from Docker Hub for use. .

2. Docker image production steps

In the process of making a Docker image, you need to create a Dockerfile first, and then build it through the Docker command. The following are the steps for making a Docker image:

1. Determine the base image

The Docker image is built based on a base image, so you need to determine a base image first. You can use an existing official image on Docker Hub or create your own base image from an existing image. Normally, it is recommended to choose the official image as the base image because you can get better quality and support.

For example, select an official image based on CentOS 7 on Docker Hub as the base image:

FROM centos:7

2. Define the required running environment in the Dockerfile

After determining the basic image, you need to define the required operating environment, configuration, dependency and other information. This information will be packaged into the Docker image as the basis of the Docker container.

For example, define the running environment as Python in the Dockerfile and install the required Python libraries:

FROM centos:7
RUN yum -y update && 
    yum -y install python36 && 
    yum clean all
RUN pip install requests

3. Add the source code to the Docker image

After defining the required running environment, the source code of the application needs to be added to the Docker image. This allows the Docker image to contain and run specific applications.

For example, add the source code in the Dockerfile:

FROM centos:7
RUN yum -y update && 
    yum -y install python36 && 
    yum clean all
RUN pip install requests
ADD ./app /app

4. Configure the command when the container starts

After adding the source code to the Docker image , you need to define the command to be run when the container starts.

For example, configure the startup command in the Dockerfile:

FROM centos:7
RUN yum -y update && 
    yum -y install python36 && 
    yum clean all
RUN pip install requests
ADD ./app /app
CMD ["python", "/app/app.py"]

In the above example, a startup command is defined, which will automatically run when the Docker container starts.

5. Build Docker Image

When the Dockerfile is completed, you need to use the Docker command to build the Docker image and publish it to Docker Hub or other image libraries.

For example, use the Docker command to build a Docker image:

docker build -t my_image .

This command uses the Docker image named "my_image" to build, using the Dockerfile file in the current directory (".") as the build file .

When the build is completed, you can use the following command to view the built Docker image:

docker images

This command will display all built Docker images, as well as their tags, IDs, sizes and other information.

6. Running a Docker container

Running a Docker image is the first step in using a Docker container. Once the Docker container is running, you can use the container to run packaged applications.

For example, use the following command to run a Docker container:

docker run -d -p 80:80 my_image

This command creates a Docker container using the "my_image" Docker image and maps port 80 of the container to port 80 of the host. This command also runs the Docker container in the background and outputs the container ID.

7. Test the Docker container

Finally, you can use a browser and other tools to open http://localhost to access the application running in the Docker container to test whether it runs successfully.

Summary:

Docker is simple to use and easy to deploy, and can quickly build, deploy and expand applications. Understanding and mastering the steps of making Docker images is very important for quickly building, deploying and running applications. This article introduces the basic concepts and production steps of Docker images. I hope readers can master the basic skills of making and using Docker images.

The above is the detailed content of Docker image production steps. For more information, please follow other related articles on the PHP Chinese website!