关于docker-compose.yaml传递特殊字符的环境变量问题

问题：

新建了一个docker-compose.yaml配置，然后启动服务，发现连不上mysql
报错：Access denied for user

分析：

1. docker-compose.yaml配置如下：

   version: "3.9"
   services:
   mysql:
   image: mysql:5.7
   container_name: mysql
   command: --default-authentication-plugin=mysql_native_password
     --character-set-server=utf8mb4 
     --collation-server=utf8mb4_unicode_ci
     --explicit_defaults_for_timestamp=true
     --lower_case_table_names=1
     --max_allowed_packet=128M
     --sql-mode="STRICT_TRANS_TABLES,NO_AUTO_CREATE_USER,NO_ENGINE_SUBSTITUTION,NO_ZERO_DATE,NO_ZERO_IN_DATE,ERROR_FOR_DIVISION_BY_ZERO"
   environment:
     - MYSQL_ROOT_PASSWORD=1234$56
   restart: always
   ports:
     - "13306:3306"
   volumes:
     - mysql-data:/var/lib/mysql
     - mysql-conf:/etc/mysql/conf.d
   
   adminer:
   image: adminer
   container_name: adminer
   restart: always
   ports:
     - 18080:8080
   depends_on:
     - mysql
   volumes:
   mysql-data: {}
   mysql-conf: {}

2. 进入mysql容器，docker exec -it mysql /bin/bash，env查看MYSQL_ROOT_PASSWORD的变量值，发现是MYSQL_ROOT_PASSWORD=1234
3. 故障点定位到，environment的MYSQL_ROOT_PASSWORD这种赋值方式异常

解决办法或者注意事项：

1. 查看官网关于环境变量定义的标准用法
   https://docs.docker.com/compose/compose-file/compose-file-v3/#environment
   https://stackoverflow.com/questions/40619582/how-can-i-escape-a-dollar-sign-in-a-docker-compose-file

2. 修正docker-compose.yaml配置

   version: "3.9"
   services:
   mysql:
   image: mysql:5.7
   container_name: mysql
   command: --default-authentication-plugin=mysql_native_password
     --character-set-server=utf8mb4 
     --collation-server=utf8mb4_unicode_ci
     --explicit_defaults_for_timestamp=true
     --lower_case_table_names=1
     --max_allowed_packet=128M
     --sql-mode="STRICT_TRANS_TABLES,NO_AUTO_CREATE_USER,NO_ENGINE_SUBSTITUTION,NO_ZERO_DATE,NO_ZERO_IN_DATE,ERROR_FOR_DIVISION_BY_ZERO"
   environment:
     - MYSQL_ROOT_PASSWORD=1234$$56
   restart: always
   ports:
     - "13306:3306"
   volumes:
     - mysql-data:/var/lib/mysql
     - mysql-conf:/etc/mysql/conf.d
   
   adminer:
   image: adminer
   container_name: adminer
   restart: always
   ports:
     - 18080:8080
   depends_on:
     - mysql
   volumes:
   mysql-data: {}
   mysql-conf: {}

3. 登录mysql容器，env校验参数成功