How to use Docker Compose to implement nginx load balancing

docker network ls

/*
NETWORK ID NAME DRIVER SCOPE
b832b168ca9a bridge bridge local
373be82d3a6a composetest_default bridge local
a360425082c4 host host local
154f600f0e90 none null local

*/

// composetest_default is the directory name where the docker-compose.yml file is located when introducing Compose in the previous article.
// Therefore, the container created with docker-compose will create a network with the directory name as the network name by default, and it is of dridge (bridge) type

version: "3"
services:
  web1:
    container_name: web1
    image: "centos:httpd"
    ports:
      - "8080:80"
    privileged: true
    volumes:
      - "/app/www/web1/:/var/www/html/"
    command: ['/usr/sbin/init']
    networks:
      nginx-lsb:
        ipv4_address: 192.169.0.3
  web2:
    container_name: web2
    image: "centos:httpd"
    ports:
      - "8081:80"
    privileged: true
    volumes:
      - "/app/www/web2/:/var/www/html/"
    command: ['/usr/sbin/init']
    networks:
      nginx-lsb:
        ipv4_address: 192.169.0.2
networks:
  nginx-lsb:
    driver: bridge
    ipam:
      config:
        - subnet: 192.169.0.0/16

docker-compose up -d

// You can view the container status in the container group configured by the current docker-compose.yml docker-compose ps

docker network ls

/*
NETWORK ID NAME DRIVER SCOPE
b832b168ca9a bridge bridge local
373be82d3a6a composetest_default bridge local
de6f5b8df1c8 composetest_nginx-lsb bridge local
a360425082c4 host host local
154f600f0e90 none null local
*/

// Created the nginx-lsb network, named after the beginning of the container group project file name_network name

docker network inspect composetest_nginx-lsb

// In the details, you can see the IP address of each container using this network.

like:

/*
...
 "Containers": {
      "039aa860ef04f20a7566fdc943fb4398a61d2ad6dd3e373b17c86ac778af89e3": {
        "Name": "web2",
        "EndpointID": "1bc206661179e65999015f132c2889d3d4365b8d42b8a89cf9c260016fedd5ee",
        "MacAddress": "02:42:c0:a9:00:02",
        "IPv4Address": "192.169.0.2/16",
        "IPv6Address": ""
      },
      "437ad7a07da8e46c0abaf845c4b08425338009fbe972bde69478cf47c75c315b": {
        "Name": "web1",
        "EndpointID": "5a36e602a5364ee9ad06e9816d09e3966d56ebf06b9394ebc25b8bcee9546607",
        "MacAddress": "02:42:c0:a9:00:03",
        "IPv4Address": "192.169.0.3/16",
        "IPv6Address": ""
      }
    },
...
*/

// Or define a .env file in the composetest directory to store the variable web1_addr=192.169.0.2
web2_addr=192.169.0.3

// Modify the docker-compose.yml file and add the variable definition version: "3"
services:
  web1:
    container_name: web1
    image: "centos:httpd"
    ports:
      - "8080:80"
    privileged: true
    volumes:
      - "/app/www/web1/:/var/www/html/"
    command: ['/usr/sbin/init']
    networks:
      nginx-lsb:
        ipv4_address: ${web1_addr}
  web2:
    container_name: web2
    image: "centos:httpd"
    ports:
      - "8081:80"
    privileged: true
    volumes:
      - "/app/www/web2/:/var/www/html/"
    command: ['/usr/sbin/init']
    networks:
      nginx-lsb:
        ipv4_address: ${web2_addr}
networks:
  nginx-lsb:
    driver: bridge
    ipam:
      config:
        - subnet: 192.169.0.0/16

// Restart the composetest project docker-compose up -d

// View network details docker network inspect composetest_nginx-lsb

// Add a variable nginx_lsb in the .env file
web1_addr=192.169.0.2
web2_addr=192.169.0.3
nginx_lsb=192.169.0.100

// Modify the docker-compose.yml file and add the variable definition version: "3"
services:
  nginx-lsb:
    container_name: nginx-lsb
    image: "centos:nginx"
    ports: 
      - "8000:80"
    privileged: true
    volumes:
      - "/app/nginx/nginx.conf:/etc/nginx/nginx.conf"
    networks:
      nginx-lsb:
        ipv4_address: ${nginx_lsb}
  web1:
    container_name: web1
    image: "centos:httpd"
    ports:
      - "8080:80"
    privileged: true
    volumes:
      - "/app/www/web1/:/var/www/html/"
    command: ['/usr/sbin/init']
    networks:
      nginx-lsb:
        ipv4_address: ${web1_addr}
  web2:
    container_name: web2
    image: "centos:httpd"
    ports:
      - "8081:80"
    privileged: true
    volumes:
      - "/app/www/web2/:/var/www/html/"
    command: ['/usr/sbin/init']
    networks:
      nginx-lsb:
        ipv4_address: ${web2_addr}
networks:
  nginx-lsb:
    driver: bridge
    ipam:
      config:
        - subnet: 192.169.0.0/16

// Restart the composetest project docker-compose up -d

upstream mydocker {
  server 192.169.0.2;
  server 192.169.0.3;
}

server {
  listen 80;
  server_name mydocker;
  location / {
    proxy_set_header Host $host;
    proxy_set_header X-Real-IP $remote_addr;
    proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
    proxy_buffering off;
    proxy_pass http://mydocker;
  }
}

docker-composer restart nginx-lsb