Spring Boot Application not able to connect with MySQL in Docker

Question

While I am going to start my spring boot application image in the docker engine with the below command then I am getting an error

The command which I am using to start my application image

docker run -p 8082:8082 --name e-health e-health

GETTING BELOW ERROR

The last packet sent successfully to the server was 0 milliseconds ago. The driver has not received any packets from the server.
        at sun.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method) ~[na:1.8.0_212]
        at sun.reflect.NativeConstructorAccessorImpl.newInstance(NativeConstructorAccessorImpl.java:62) ~[na:1.8.0_212]
        at sun.reflect.DelegatingConstructorAccessorImpl.newInstance(DelegatingConstructorAccessorImpl.java:45) ~[na:1.8.0_212]
        at java.lang.reflect.Constructor.newInstance(Constructor.java:423) ~[na:1.8.0_212]
        at com.mysql.cj.exceptions.ExceptionFactory.createException(ExceptionFactory.java:61) ~[mysql-connector-java-8.0.23.jar!/:8.0.23]
        at com.mysql.cj.exceptions.ExceptionFactory.createException(ExceptionFactory.java:105) ~[mysql-connector-java-8.0.23.jar!/:8.0.23]
        at com.mysql.cj.exceptions.ExceptionFactory.createException(ExceptionFactory.java:151) ~[mysql-connector-java-8.0.23.jar!/:8.0.23]
        at com.mysql.cj.exceptions.ExceptionFactory.createCommunicationsException(ExceptionFactory.java:167) ~[mysql-connector-java-8.0.23.jar!/:8.0.23]
        at com.mysql.cj.protocol.a.NativeSocketConnection.connect(NativeSocketConnection.java:89) ~[mysql-connector-java-8.0.23.jar!/:8.0.23]
        at com.mysql.cj.NativeSession.connect(NativeSession.java:144) ~[mysql-connector-java-8.0.23.jar!/:8.0.23]
        at com.mysql.cj.jdbc.ConnectionImpl.connectOneTryOnly(ConnectionImpl.java:953) ~[mysql-connector-java-8.0.23.jar!/:8.0.23]
        at com.mysql.cj.jdbc.ConnectionImpl.createNewIO(ConnectionImpl.java:823) ~[mysql-connector-java-8.0.23.jar!/:8.0.23]
        ... 57 common frames omitted
Caused by: java.net.UnknownHostException: mysqldb
        at java.net.InetAddress.getAllByName0(InetAddress.java:1281) ~[na:1.8.0_212]
        at java.net.InetAddress.getAllByName(InetAddress.java:1193) ~[na:1.8.0_212]
        at java.net.InetAddress.getAllByName(InetAddress.java:1127) ~[na:1.8.0_212]
        at com.mysql.cj.protocol.StandardSocketFactory.connect(StandardSocketFactory.java:132) ~[mysql-connector-java-8.0.23.jar!/:8.0.23]
        at com.mysql.cj.protocol.a.NativeSocketConnection.connect(NativeSocketConnection.java:63) ~[mysql-connector-java-8.0.23.jar!/:8.0.23]
        ... 60 common frames omitted

I have created a MySQL container with the below command

docker run -d -p 3306:3306 --name mysqldb -e MYSQL_ROOT_PASSWORD=123456789 -e MYSQL_DATABASE=eHealth mysql

I have created my Spring boot application Image with below command

docker build -t e-health .

My Spring Boot project application.properties file looks like below

spring.datasource.name=eHealth
spring.datasource.url=jdbc:mysql://mysqldb:3306/eHealth
spring.datasource.username=root
spring.datasource.password=123456789
spring.datasource.driver-class-name=com.mysql.cj.jdbc.Driver
spring.jpa.properties.hibernate.dialect=org.hibernate.dialect.MySQL8Dialect
spring.jpa.hibernate.ddl-auto=update
spring.jpa.show-sql=true
server.port=8082

My Dockerfile looks like below

FROM openjdk:8-jdk-alpine
ARG JAR_FILE=target/eHealth.jar
WORKDIR /opt/app
COPY ${JAR_FILE} app.jar
ENTRYPOINT ["java","-jar","app.jar"]

Docker container Looks like

I have followed the below question but it's not helping me Spring Boot MySQL Docker Caused by: java.net.ConnectException: Connection refused (Connection refused)

Any suggestions or solutions, Please

As per the suggestion I have tried to create a container like below also, But still I am getting the same error

docker run -d -p 3306:3306 --name mysqldb --hostname=mysqldb -e MYSQL_ROOT_PASSWORD=123456789 -e MYSQL_DATABASE=eHealth MySQL


CONTAINER ID   IMAGE     COMMAND                  CREATED         STATUS         PORTS                               NAMES
469e171ff3e2   mysql     "docker-entrypoint.s…"   5 seconds ago   Up 4 seconds   0.0.0.0:3306->3306/tcp, 33060/tcp   mysqldb

Answer 1

it depends on your use case if you are trying to run both the spring boot application and MySQL in docker, you need to make sure that both containers are in the same network.

one solution is to manually create the networks using the docker command and run both container on this created network. or an easier solution is to write a docker-compose.yml file

by default the docker-compose.yml will create a default network.

docker-compose.yml

version: '3'
services:
  mysql-standalone:
    image: mysql:latest
    environment:
      - MYSQL_ROOT_PASSWORD=***
      - MYSQL_DATABASE=***
      - MYSQL_USER=***
      - MYSQL_PASSWORD=**

    volumes:
      - data:/var/lib/mysql

  spring-boot:
    image: *your-app-name-image*
    ports:
      [8080:8080]
    build:
      context: ./
      dockerfile: Dockerfile

    depends_on:
      - mysql-standalone

volumes:
  data:

you can also create your own network like the following

networks:
  mynetwork:
    driver: bridge

so your docker-compose.yml file will look like the following

version: '3'
services:
  mysql-standalone:
    image: mysql:latest
    environment:
      - MYSQL_ROOT_PASSWORD=***
      - MYSQL_DATABASE=***
      - MYSQL_USER=***
      - MYSQL_PASSWORD=**

    volumes:
      - data:/var/lib/mysql
    networks:
      - mynetwork

  spring-boot:
    image: *your-app-name-image*
    ports:
      [8080:8080]
    build:
      context: ./
      dockerfile: Dockerfile

    depends_on:
      - mysql-standalone
    networks:
      - mynetwork

volumes:
  data:

networks:
  mynetwork:
    driver: bridge

in your application.yml file you need to have the following

 server.port=8080
 spring.datasource.url=jdbc:mysql://<container-name>:3306/<db-name>
 spring.datasource.username=***
 spring.datasource.password=***

I would suggest having multiple profiles using the spring profile.

2. The second use case is if you are running MySQL in a container and your spring boot application locally, then you need to change this:

spring.datasource.url=jdbc:mysql://mysqldb:3306/eHealth

to

spring.datasource.url=jdbc:mysql://localhost:3306/eHealth

this should solve the error mentioned Caused by: java.net.UnknownHostException: mysqldb.

if you decided that writing a docker-compose.yml file does not suit your use case, check this https://docs.docker.com/engine/reference/commandline/network_create/ to check how to create networks from the command line