如何在 application.properties 文件中指定环境变量，以便我的应用程序可以在 Z38008DCCA73AZ 中使用 Docker 容器 MySQL 不是本地 MySQL？

Question

i'm new to Dockers,i want my spring application to access MySQL db from container but i don't know how to add environment variables in docker-compose file and application.properties file so my application can use MySQL db containing in Docker MySQL image.but make sure this is spring application not spring boot

below is the docker-compose file i tried to write

 version: '3'
services:
  mysql-standalone:
    image: 'mysql:5.7'
    environment:
      - MYSQL_ROOT_PASSWORD=root
      - MYSQL_USER=root
      - MYSQL_PASSWORD=root
      - MYSQL_DATABASE=CTH
    ports:
      - "3307:3306"
  cth-docker-container:
    image: cth-docker-container
    ports:
      - "8082:8082"
    environment:
      CTH_MYSQL_DATABASENAME: CTH
      CTH_MYSQL_SERVERNAME: mysql-standalone
      CTH_MYSQL_USERNAME: root
      CTH_MYSQL_PASSWORD: root

      CTH_CHAT_MYSQL_DATABASENAME: CTH_CHAT
      CTH_CHAT_MYSQL_SERVERNAME: mysql-standalone
      CTH_CHAT_MYSQL_USERNAME: root
      CTH_CHAT_MYSQL_PASSWORD: root
    build:
      context: "./"
      dockerfile: "Dockerfile"
    depends_on:
      - mysql-standalone

and application.properties file which has db properties

dbuser.local=root
dbpassword.local=root
dbdatabaseName.local=CTH
dbserverName.local=localhost
dbportNumber.local=3306

i don't know how to create environment variables so my application knows to use use MySQL db present inside MySQL-standalone image

Answer 1

With docker-compose you create a container.

Inside your container there are:

• database= CTH
• username = root
• password = root
• port = 3307(port expose outside):3306(port expose inside container)

if you want to connect to database from your Spring application you have to change your application.properties like this:

• spring.datasource.url=jdbc:mysql://localhost:3307/CTH
• spring.datasource.username=root
• spring.datasource.password=root
• spring.datasource.driver-class-name=com.mysql.jdbc.Driver

(you can find properties in this site https://spring.io/guides/gs/accessing-data-mysql/ under "Create the application.properties File" section)

Answer 2

Finally, I found how to create environment variables in the application.properties file which can consume data from the docker-compose file and can able to give values when my application is running locally.

key.name=${value_consuming_from_docke_compose_file:i_can_give_value_when_application_is running_locally}

this is the way but anyone gets another way stuck in a different scenario please find the answer and post here.

Thanks!