Let's talk about the difference between Docker Compose and Dockerfile

This article brings you relevant knowledge about Docker. It mainly introduces to you what Docker Compose and Dockerfile are, and what are the differences between them. Friends who are interested should take a look. ,I hope everyone has to help.

1. The difference between Docker Compose and Dockerfile

Docker Compose and Dockerfile are both tools for building and managing Docker containers, but they have different functions and uses. Way.

• Dockerfile is a text file used to define the building rules of a Docker image. It contains a series of instructions for specifying the operating system, software environment, application, file copy and other information when the container is running. Through Dockerfile, you can build a customized Docker image so that the image can run on any host that supports Docker.

• Docker Compose is a tool for defining and running multiple Docker containers. With Docker Compose, you can use YAML files to describe the application's services, network, storage and other resources, and use a single command to start, stop, restart and manage the entire application. In a Docker Compose configuration file, multiple Docker containers can be defined, each container can use a customized Docker image, and the dependencies and communication methods between containers can be specified.

Therefore, Dockerfile is more used to create and customize Docker images, while Docker Compose is more used to manage multiple Docker containers so that they can work together to build a complete app.

2. Example

Suppose you want to run a PHP web application on a CentOS 7 system and use Nginx as the web server. You can use Dockerfile and Docker Compose to fulfill.

Using Dockerfile, you can create a custom PHP Nginx image, for example:

FROM php:7.4-fpm
RUN apt-get update && apt-get install -y nginx
COPY nginx.conf /etc/nginx/nginx.conf
WORKDIR /var/www/html
COPY src/ /var/www/html/
EXPOSE 80
CMD ["nginx", "-g", "daemon off;"]

This Dockerfile is based on the official PHP 7.4-fpm image, installed Nginx, and copied the application code to In the /var/www/html directory of the container. The image also maps port 80 of the container to the host so that the application can be accessed from the host through a browser.

Using Docker Compose, you can define a YAML file to start two containers of PHP and Nginx at the same time and connect them to the same Docker network. For example:

`version: '3'
services:
  php:
    image: php:7.4-fpm
    volumes:
      - ./src:/var/www/html
    networks:
      - my-network
  nginx:
    image: nginx:latest
    ports:
      - "80:80"
    volumes:
      - ./nginx.conf:/etc/nginx/nginx.conf
    networks:
      - my-network
networks:
  my-network:`

This Docker Compose file defines two services: one is based on the official PHP 7.4-fpm image, and the other is based on the official Nginx image. They both mount the local application code and Nginx configuration files and connect them to a Docker network called my-network. In addition, port 80 of the Nginx container is also mapped to port 80 of the host.

In general, Dockerfile is better for creating and customizing a single image, while Docker Compose is better for managing multiple containers and combining them together to build a complete application. In this example, you can use Dockerfile to create a custom PHP Nginx image, and use Docker Compose to start both PHP and Nginx containers at the same time and connect them to the same Docker network.

Recommended learning: docker video tutorial, docker usage tutorial

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