Failed to configure a DataSource: ‘url’ attribute is not specified and no embedded datasource could be configured

Problem:

If you’re working with Spring Boot, you might encounter the following error:

Failed to configure a DataSource: 'url' attribute is not specified and no embedded 
datasource could be configured.

Reason: Failed to determine a suitable driver class.

This error generally occurs when you’ve included the Spring Boot Data JPA starter dependency, and Spring Boot’s auto-configuration tries to create a DataSource:

<dependency>
    <groupId>org.springframework.boot</groupId>
    <artifactId>spring-boot-starter-data-jpa</artifactId>
</dependency>

Here are three main approaches to resolving this issue:

• Define Spring DataSource properties in the configuration file.
• Manually configure the DataSource.
• Disable Spring Boot’s DataSource auto-configuration.

Solution 1: Define Spring DataSource Properties in the Configuration File

To define the necessary DataSource properties, use either application.properties or application.yml. Below are examples for both:

In application.properties:

spring.datasource.url=jdbc:mysql://localhost:3306/your_db
spring.datasource.username=your_username
spring.datasource.password=your_password
spring.datasource.driver-class-name=com.mysql.cj.jdbc.Driver

In application.yml:

spring:
  datasource:
    url: jdbc:mysql://localhost:3306/your_db
    username: your_username
    password: your_password
    driver-class-name: com.mysql.cj.jdbc.Driver

Solution 2: Manually Configure the DataSource

You can also define the DataSource bean manually within a @Configuration class. Here is an example:

import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import org.springframework.boot.jdbc.DataSourceBuilder;

import javax.sql.DataSource;

@Configuration
public class DataSourceConfig {

    /**
     * Configure a DataSource bean for the application.
     * This example uses a username/password-based connection.
     * 
     * @return DataSource configured for the application.
     */
    @Bean
    public DataSource dataSource() {
        return DataSourceBuilder.create()
                .url("jdbc:mysql://localhost:3306/your_db")
                .username("your_username")
                .password("your_password")
                .driverClassName("com.mysql.cj.jdbc.Driver")
                .build();
    }
}

Solution 3: Disable Spring Boot’s DataSource Auto-Configuration

If you prefer not to configure a DataSource, you can disable Spring Boot’s auto-configuration for DataSource in your main application class:

import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.boot.autoconfigure.jdbc.DataSourceAutoConfiguration;

@SpringBootApplication(exclude = {DataSourceAutoConfiguration.class})
public class YourApplication {

    public static void main(String[] args) {
        SpringApplication.run(YourApplication.class, args);
    }
}

Managing Different Environments with Profiles

Spring Boot supports profiles to manage different configurations for various environments like development, testing, and production. This can be handled using profile-specific application.yml files:

• application.yml
• application-local.yml
• application-dev.yml
• application-uat.yml

Each of these files can contain environment-specific DataSource configurations. Here’s an example for a development environment in application-dev.yml:

spring:
  datasource:
    url: jdbc:mysql://localhost:3306/dev_db
    username: dev_user
    password: dev_password
    driver-class-name: com.mysql.cj.jdbc.Driver

To activate a specific profile, set the spring.profiles.active property in your main application.yml:

spring:
  profiles:
    active: dev

If no profile is specified, Spring Boot defaults to the configurations in application.yml. However, specified profiles override these defaults.