如何设置 Java JDBC 环境变量？

Question

我正在构建一个使用 Vanilla JDBC 连接到 postgres 数据库的简单 Java 8 应用程序。在ConnectionUtil.java 中的getConnection() 方法中，我将连接凭据保存在以下变量中：

        String url = System.getenv("DB_URL");
        String username = System.getenv("DB_USERNAME");
        String password = System.getenv("DB_PASSWORD");

我的docker-compose.yml文件如下：

version: "3.9"

services:
  jdbc:
    build: .
    ports:
    - 7000:7000
    volumes:
    - ./logs/log.txt:/logs\log.txt
    environment:
    - DB_URL
    - DB_USERNAME
    - DB_PASSWORD
    container_name: jdbc

更多内容，这里是我的Dockerfile：

# Base image with jdk 8 and maven
FROM maven:3.6.3-openjdk-8 as builder

# Copy pom.xml and source-code
COPY pom.xml pom.xml
COPY src/ src/

# Build application
RUN mvn clean package

# As a separate stage, to save on resulting image size, discard everything from previous stages
FROM java:8 as runner
# Base image only needs JRE 8

# Expose port 7000 for our web-app
EXPOSE 7000

# Copy the jar file from previous stage
COPY --from=builder target/jdbc-demo-jar-with-dependencies.jar app.jar

# Run program
ENTRYPOINT [ "java", "-jar", "app.jar" ]

我还在学习 Docker。我的问题是，我在哪里设置环境变量？

Answer 1

在您当前的 docker-compose.yaml 中，您声明了环境变量而没有初始化它们，只需给它们值。

像这样：

version: "3.9"

services:
  jdbc:
    build: .
    ports:
    - 7000:7000
    volumes:
    - ./logs/log.txt:/logs\log.txt
    environment:
    - DB_URL=https://db.address.com
    - DB_USERNAME=db_username
    - DB_PASSWORD=db_password
    container_name: jdbc