docker passes the container's environment variables

This case takes springboot as an example

第一种

application.properties

spring.datasource.url=jdbc:mysql://${DB_IP}:${DB_PORT}/${DB_NAME}?useUnicode=true&characterEncoding=UTF-8&autoReconnect=true&serverTimezone=${tz:GMT-6}
spring.datasource.username=${DB_USER}
spring.datasource.password=${DB_PWD}
spring.datasource.driver-class-name=com.mysql.cj.jdbc.Driver

Dockerfile:

FROM openjdk:8-jre-slim
MAINTAINER cdn

PARAMS=""
ENV TZ=GMT-6
RUN ln -snf /usr/share/zoneinfo/$TZ /etc/localtime