Unable to connect Spring JDBC + MySQL using Docker Container

Question

I'm using Eclipse for my Spring Boot application. I want to use Docker container for my jdk and mysql.

The problem is container(Spring) refused to connect to container(mysql). FYI, I run container(mysql) in other software and it works fine. I can access the database.

I tried to run docker compose down --rmi all and run again docker compose up --build but same error appears

I keep getting these errors in my logs:

Could not create connection to database server. Attempted reconnect 3 times. Giving up.

Failed to initialize JPA EntityManagerFactory: [PersistenceUnit: default] Unable to build Hibernate SessionFactory; nested exception is org.hibernate.exception.JDBCConnectionException: Unable to open JDBC Connection for DDL execution [Could not create connection to database server. Attempted reconnect 3 times. Giving up.

Error creating bean with name 'entityManagerFactory' defined in class path resource [org/springframework/boot/autoconfigure/orm/jpa/HibernateJpaConfiguration.class]: [PersistenceUnit: default] Unable to build Hibernate SessionFactory; nested exception is org.hibernate.exception.JDBCConnectionException: Unable to open JDBC Connection for DDL execution [Could not create connection to database server. Attempted reconnect 3 times. Giving up.

Appreciate if someone can help me . I've been stuck for week now for this issue .

Dockerfile

FROM maven:3.9.6-eclipse-temurin-21 AS build
WORKDIR /home/app

COPY ./pom.xml /home/app/pom.xml
COPY ./src/main/java/project/ProjectApplication.java /home/app/src/main/java/project/ProjectApplication.java

RUN mvn -f /home/app/pom.xml clean package

COPY . /home/app
RUN mvn -f /home/app/pom.xml clean package

# Set the Spring Boot datasource URL
ENV SPRING_DATASOURCE_URL=jdbc:mysql://docker-mysql:3306/restapidb?autoReconnect=true&useSSL=false&allowPublicKeyRetrieval=true

FROM openjdk:21-slim-bullseye
VOLUME /tmp
EXPOSE 8080
COPY --from=build /home/app/target/*.jar app.jar
ENTRYPOINT [ "sh", "-c", "java -jar /app.jar"]

docker-compose.yml

version: '3.8'

services:
  docker-mysql:
    image: mysql:8.0
    container_name: mysqleclipse
    environment:
      MYSQL_ROOT_PASSWORD: Pass1234
      MYSQL_DATABASE: testdb
      MYSQL_USER: testuser
      MYSQL_PASSWORD: Pass1234
    ports:
      - "3306:3306"  # Map port 3306 on the host to port 3306 on the container

  spring-app:
    build:
      context: .
      dockerfile: Dockerfile
    container_name: springbootjdbc
    ports:
      - "8080:8080"  # Map port 8080 on the host to port 8080 on the container
    depends_on:
      - docker-mysql

Pom.xml

<?xml version="1.0" encoding="UTF-8"?>
<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
    xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 https://maven.apache.org/xsd/maven-4.0.0.xsd">
    <modelVersion>4.0.0</modelVersion>
    <parent>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-parent</artifactId>
        <version>3.2.1</version>
        <relativePath/> <!-- lookup parent from repository -->
    </parent>
    <groupId>my.com.exim</groupId>
    <artifactId>jdbc-project9</artifactId>
    <version>0.0.1-SNAPSHOT</version>
    <name>jdbc-project9</name>
    <description>Demo project for Spring Boot</description>
    <properties>
        <java.version>21</java.version>
    </properties>
    <dependencies>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-data-jpa</artifactId>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-validation</artifactId>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-web</artifactId>
        </dependency>

        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-devtools</artifactId>
            <scope>runtime</scope>
            <optional>true</optional>
        </dependency>
        
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-data-jdbc</artifactId>
        </dependency>
        
        <dependency>
            <groupId>com.mysql</groupId>
            <artifactId>mysql-connector-j</artifactId> 
            <scope>runtime</scope>
        </dependency> 
        
        
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-test</artifactId>
            <scope>test</scope>
        </dependency>
    </dependencies>

    <build>
        <plugins>
            <plugin>
                <groupId>org.springframework.boot</groupId>
                <artifactId>spring-boot-maven-plugin</artifactId> 
            </plugin>
            <plugin>
                <groupId>org.apache.maven.plugins</groupId>
                <artifactId>maven-surefire-plugin</artifactId>
                <version>2.19</version>
            </plugin>
        </plugins>
    </build>

</project>

application.properties

server.port=8080
spring.datasource.url=jdbc:mysql://docker-mysql:3306/restapidb?autoReconnect=true&useSSL=false&allowPublicKeyRetrieval=true&serverTimezone=UTC
spring.datasource.username=testuser
spring.datasource.password=Pass1234
spring.datasource.driver-class-name=com.mysql.cj.jdbc.Driver

spring.jpa.properties.hibernate.dialect=org.hibernate.dialect.MySQL8Dialect
spring.jpa.show-sql=true
spring.jpa.hibernate.ddl-auto=update

HelloWorld.java

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.boot.CommandLineRunner;
import org.springframework.jdbc.core.JdbcTemplate;
import org.springframework.stereotype.Component;

@Component
public class HelloWorld implements CommandLineRunner {

    private final JdbcTemplate jdbcTemplate;

    @Autowired
    public HelloWorld(JdbcTemplate jdbcTemplate) {
        this.jdbcTemplate = jdbcTemplate;
    }

    @Override
    public void run(String... args) throws Exception {
        testJdbcConnection();
    }

    private void testJdbcConnection() {
        try {
            // Perform a simple query to test the connection
            Integer count = jdbcTemplate.queryForObject("SELECT COUNT(*) FROM tables", Integer.class);
            System.out.println("Connection successful! Rows in the table: " + count);
        } catch (Exception e) {
            System.err.println("Error testing JDBC connection: " + e.getMessage());
        }
    }
}