Docker撰写错误上mysql db连接为Spring启动应用程序引起的：java.net.未知的主机异常：[重复]

Question

我有Spring靴应用

我的文件是

FROM openjdk:8-jdk-alpine
EXPOSE 8080
ARG JAR_FILE=target/demo-0.0.1-SNAPSHOT.jar
ADD ${JAR_FILE} demo.jar
ENTRYPOINT ["java","-jar","/demo.jar"]


My docker compose file
# Docker Compose file Reference (https://docs.docker.com/compose/compose-file/)

version: '3.7'

# Define services
services:
  # App backend service
  app-server:
    # Configuration for building the docker image for the backend service
    build:
      context: . # Use an image built from the specified dockerfile in the `polling-app-server` directory.
      dockerfile: ./Dockerfile
    container_name: empserver
    ports:
      - "3000:3000" # Forward the exposed port 8080 on the container to port 8080 on the host machine
    restart: always
    depends_on: 
      - db # This service depends on mysql. Start that first.
    environment: # Pass environment variables to the service
      SPRING_DATASOURCE_URL: jdbc:mysql://db:3306/employee_entries?useSSL=false&serverTimezone=UTC&useLegacyDatetimeCode=false
      SPRING_DATASOURCE_USERNAME: root
      SPRING_DATASOURCE_PASSWORD: root     

  # Database Service (Mysql)
  db:
    image: mysql:5.7
    ports:
      - "3306:3306"
    restart: always
    environment:
      MYSQL_DATABASE: employee_entries
      MYSQL_USER: root
      MYSQL_PASSWORD: root
      MYSQL_ROOT_PASSWORD: root

我的docker网络工作正常

NETWORK ID          NAME                DRIVER              SCOPE
b95e3d99b266        Default Switch      ics                 local
7fff4f9713f8        demo_default        nat                 local
fe8883b77d1d        emp-mysql           ics                 local
f464aab9064a        nat                 nat                 local
a5bd5e8efe61        none                null                local

应用程序正在使用java-jar-target\demo-0.0.1-SNAPSHOT成功运行。罐子

但当我做docker作曲的时候

我犯了错误

app-server_1  | Caused by: com.mysql.cj.exceptions.CJCommunicationsException: Communications link failure
app-server_1  |
app-server_1  | The last packet sent successfully to the server was 0 milliseconds ago. The driver has not received any packets from the server.
app-server_1  |         at sun.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method) ~[na:1.8.0_212]
app-server_1  |         at sun.reflect.NativeConstructorAccessorImpl.newInstance(NativeConstructorAccessorImpl.java:62) ~[na:1.8.0_212]
app-server_1  |         at sun.reflect.DelegatingConstructorAccessorImpl.newInstance(DelegatingConstructorAccessorImpl.java:45) ~[na:1.8.0_212]
app-server_1  |         at java.lang.reflect.Constructor.newInstance(Constructor.java:423) ~[na:1.8.0_212]
app-server_1  |         at com.mysql.cj.exceptions.ExceptionFactory.createException(ExceptionFactory.java:61) ~[mysql-connector-java-8.0.19.jar!/:8.0.19]
app-server_1  |         at com.mysql.cj.exceptions.ExceptionFactory.createException(ExceptionFactory.java:105) ~[mysql-connector-java-8.0.19.jar!/:8.0.19]
app-server_1  |         at com.mysql.cj.exceptions.ExceptionFactory.createException(ExceptionFactory.java:151) ~[mysql-connector-java-8.0.19.jar!/:8.0.19]
app-server_1  |         at com.mysql.cj.exceptions.ExceptionFactory.createCommunicationsException(ExceptionFactory.java:167) ~[mysql-connector-java-8.0.19.jar!/:8.0.19]
app-server_1  |         at com.mysql.cj.protocol.a.NativeSocketConnection.connect(NativeSocketConnection.java:91) ~[mysql-connector-java-8.0.19.jar!/:8.0.19]
app-server_1  |         at com.mysql.cj.NativeSession.connect(NativeSession.java:144) ~[mysql-connector-java-8.0.19.jar!/:8.0.19]
app-server_1  |         at com.mysql.cj.jdbc.ConnectionImpl.connectOneTryOnly(ConnectionImpl.java:956) ~[mysql-connector-java-8.0.19.jar!/:8.0.19]
app-server_1  |         at com.mysql.cj.jdbc.ConnectionImpl.createNewIO(ConnectionImpl.java:826) ~[mysql-connector-java-8.0.19.jar!/:8.0.19]
app-server_1  |         ... 56 common frames omitted
app-server_1  | Caused by: java.net.UnknownHostException: db
app-server_1  |         at java.net.InetAddress.getAllByName0(InetAddress.java:1281) ~[na:1.8.0_212]
app-server_1  |         at java.net.InetAddress.getAllByName(InetAddress.java:1193) ~[na:1.8.0_212]
app-server_1  |         at java.net.InetAddress.getAllByName(InetAddress.java:1127) ~[na:1.8.0_212]
app-server_1  |         at com.mysql.cj.protocol.StandardSocketFactory.connect(StandardSocketFactory.java:132) ~[mysql-connector-java-8.0.19.jar!/:8.0.19]
app-server_1  |         at com.mysql.cj.protocol.a.NativeSocketConnection.connect(NativeSocketConnection.java:65) ~[mysql-connector-java-8.0.19.jar!/:8.0.19]
app-server_1  |         ... 59 common frames omitted

我可以访问mysql数据库和表，但从docker compose无法访问

任何建议都会很有帮助

Answer 1

您需要向服务提供容器名称，并在相互引用它们时使用它们。在您的应用服务器环境部分中，数据库的url指向127.0.0.1但数据库与应用服务器不在同一个容器上运行，因此这将失败。要使此工作正常，请向服务提供容器名称，例如：my_mysql和my_app服务器，并在环境url中使用它作为jdbc： mysql：//my_mysql： 3306。请参阅下面的修改文件：

# Docker Compose file Reference (https://docs.docker.com/compose/compose-file/)

version: '3.7'

# Define services
services:
  # App backend service
  app-server:
    # Configuration for building the docker image for the backend service
    build:
      context: . # Use an image built from the specified dockerfile in the `polling-app-server` directory.
      dockerfile: ./Dockerfile
    container_name: my_app-server
    ports:
      - "3000:3000" # Forward the exposed port 8080 on the container to port 8080 on the host machine
    restart: always
    depends_on: 
      - db # This service depends on mysql. Start that first.
    environment: # Pass environment variables to the service
      SPRING_DATASOURCE_URL: jdbc:mysql://my_mysql:3306/employee_entries?useSSL=false&serverTimezone=UTC&useLegacyDatetimeCode=false
      SPRING_DATASOURCE_USERNAME: root
      SPRING_DATASOURCE_PASSWORD: root     

  # Database Service (Mysql)
  db:
    image: mysql:5.7
    container_name: my_mysql
    ports:
      - "3306:3306"
    restart: always
    environment:
      MYSQL_DATABASE: employees
      MYSQL_USER: root
      MYSQL_PASSWORD: root
      MYSQL_ROOT_PASSWORD: root
network:
  my-network: