Table of contents

introduction

1. Introduction to Docker-compose

2. YAML file format and preparation precautions

2.1, YAML file format

2.2. Notes on YAML format

2.3, YAML data structure

3. Docker Compose configuration common fields

Fourth, Docker-compose common commands

Five, compose deployment

6. Summary

introduction

        Dockerfile allows users to manage a single application container, while Compose allows users to define a set of associated application containers (called a project) in a template (YAML), such as a Web server plus backend. Database service containers, etc.

1. Introduction to Docker-compose

The Docker-compose project is an official Docker open source project based on Python, which is responsible for the rapid orchestration of Docker container clusters.

Docker-compose divides the managed containers into three layers, namely project, service and container.

1. All files in the Docker-Compose running directory (docker-compose.yml, extends file or environment variable file, etc.) form a project. If there is no special specified project name, it is the current directory name.
2. A project can contain multiple services, and each service defines the image, parameters, and dependencies of the container running.
3. A service can include multiple container instances. Docker-compose does not solve the problem of load balancing, so it is necessary to use other tools to realize service discovery and load balancing, such as Consul

The project configuration file of Docker-Compose is docker-compose.yml by default, which can be accessed through environment variable The COMPOSE_FILE or -f parameter customizes the configuration file, which defines multiple dependent services and the container that each service runs.

Using a Dockerfile template file allows users to easily define a single application container. At work, there are often situations where multiple containers are required to cooperate with each other to complete a certain task. For example, to implement a Web project, in addition to the Web service container itself, it is often necessary to add a back-end database service container, and even a load balancing container.

Compose allows users to define a set of associated application containers as a project through a single docker-compose.yml template file (YAML format).

The Docker-Compose project is written in Python and calls the API provided by the Docker service to manage containers. Therefore, as long as the operating platform supports the Docker API, you can use Compose on it for orchestration management.
 

2. YAML file format and preparation precautions

2.1, YAML file format

1. YAML is a markup language that can display data serialization format intuitively and is highly readable.
2. Similar to json data description language, the syntax is much simpler than json.
3. YAML data structures are represented by indentation, consecutive items are represented by minus signs, key-value pairs are separated by colons, arrays are enclosed in square brackets [ ], and hash es are enclosed in curly braces { }.

2.2. Notes on YAML format

1. tab indentation is not supported, only spaces are used for indentation
2. Usually indent 2 spaces at the beginning
3. Indent 1 space after characters, such as colon : , comma , , dash -
4. Comment with #
5. If it contains special characters, use single quotation marks '' as ordinary characters; if use double quotation marks "", it means the special characters themselves
6. Boolean values ​​must be enclosed in quotes ""
7. Case sensitive

2.3, YAML data structure

object: dictionary of key-value pairs
animal: pets

array: A set of ordered lists
- cat
- dog
- goldfish

Boolean value
debug: "true"
debug: "false"


#Yaml example
languages:  #sequence mapping
  - Java
  - Golang
  - Python
websites:   #map to map
  Baidu: www.baidu.com
  Wangyi: www.163.com
  Souhu: www.souhu.com
  
 
#or 
languages: ["Java","Golong","Python"]
websites: 
  Baidu: 
    www.baidu.com
  Wangyi: 
    www.163.com
  Souhu: 
    www.souhu.com
 
 
 
#Json format
{
  languages: [
    'Java',
    'Golong',
    'Python',
  ],
  websites: [
    Baidu: 'www.baidu.com',
    Wangyi: 'www.163.com',
    Souhu: 'www.souhu.com',
  ]
}

3. Docker Compose configuration common fields

Fourth, Docker-compose common commands

Five, compose deployment

Docker-Compose is an independent product of Docker, so you need to install Docker Compose separately after installing Docker.

//Environment deployment All hosts install the docker environment (the content is the docker foundation)
yum install docker-ce -y
//Download compose (upload docker_compose)
curl -L https://github.com/docker/compose/releases/download/1.21.1/docker-compose-`uname -s`-`uname -m` -o /usr/local/bin/docker-compose
cp -p docker-compose /usr/local/bin/
chmod +x /usr/local/bin/docker-compose

mkdir /root/compose_nginx

yum install -y tree



vim /root/compose_nginx/docker-compose.yml

version: '3'
services:
  nginx:
    hostname: nginx
    build:
      context: ./nginx
      dockerfile: Dockerfile
    ports:
       - 1216:80
       - 1217:443
    networks:
       - cluster     
    volumes:
       - ./wwwroot:/usr/local/nginx/html
networks:
  cluster:

 ​​​​

[root@docker /]# mkdir /opt/compose_nginx
[root@docker /]# vim /opt/compose_nginx/docker-compose.yml
[root@docker /]# vim /opt/compose_nginx/docker-compose.yml
[root@docker /]# cd /opt/compose_nginx/
[root@docker compose_nginx]# ls
docker-compose.yml
[root@docker compose_nginx]# mkdir nginx
[root@docker compose_nginx]# mkdir wwwroot
[root@docker compose_nginx]# ls
docker-compose.yml  nginx  wwwroot
[root@docker compose_nginx]# echo "i am superman" > wwwroot/index.html
[root@docker compose_nginx]# cat wwwroot/index.html
i am superman
[root@docker compose_nginx]# cd nginx
[root@docker nginx]# ls
nginx-1.22.0.tar.gz
[root@docker nginx]#

[root@docker nginx]# vim Dockerfile 

FROM centos:7 as build
ADD nginx-1.22.0.tar.gz /mnt
WORKDIR /mnt/nginx-1.22.0
RUN yum install -y gcc pcre pcre-devel devel zlib-devel make &> /dev/null && \
 yum clean all && \
 sed -i 's/CFLAGS="$CFLAGS -g"/#CFLAGS="$CFLAGS -g"/g' auto/cc/gcc && \
 ./configure --prefix=/usr/local/nginx &> /dev/null && \
 make &>/dev/null && \
 make install &>/dev/null && \
 rm -rf /mnt/nginx-1.22.0

FROM centos:7
EXPOSE 80
VOLUME ["/usr/local/nginx/html"]
COPY --from=build /usr/local/nginx /usr/local/nginx
CMD ["/usr/local/nginx/sbin/nginx","daemon off;"]

[root@docker compose_nginx]# tree ./
./
├── docker-compose.yml
├── nginx
│   ├── dockerfile
│   └── nginx-1.22.0.tar.gz
└── wwwroot
    └── index.html

2 directories, 4 files

docker-compose -f docker-compose.yml up -d
docker network ls

6. Summary

The project configuration file of Docker-Compose defaults to docker-compose.yml
Using a Dockerfile template file allows users to easily define a single application container.
Compose allows users to define a set of associated application containers as a project through a single docker-compose.yml template file (YAML format).
docker-compose is divided into three layers: project, service, container

project: represents a project composed of multiple service s. The default is to use the name of the working directory as the project name of the project
service: A service can contain one or more containers, in which parameters such as network mode port mirroring data volumes can be defined
container: can be implemented directly by running an existing image, or by building an image through dockerfile