How to use HikariCP in Spring Boot with two datasources in conjunction with Flyway

Question

I want to use HikariCP as JDBC connection pool in my Spring boot application. I have two datasources (MySQL database as the primary database and accessing those data through Hib

Answer 1

Declaring your own DataSource will already have implicity disabled Spring Boot's auto-configuration of a data source. In other words this won't be having any effect:

@EnableAutoConfiguration(exclude = {DataSourceAutoConfiguration.class})

I think the problem lies in the fact that you aren't binding Hikari-specific configuration to your MySQL DataSource. You need to do something like this:

@Bean
@Primary
@ConfigurationProperties("spring.datasource.hikari")
public DataSource mySQLDataSource() {
    return mySQLDataSourceProperties().initializeDataSourceBuilder().build();
}

This will mean that your mySQLDataSourceProperties are configured with general-purpose data source configuration. They then create a HikariDataSource which is further configured with the Hikari-specific configuration.

Answer 2

Thank you Andy for your fast and valuable answer ! You set me on the right track. After fiddling around, I found this configuration is working for me :

    @Bean
    @Primary
    @ConfigurationProperties("spring.datasource") 
  //@ConfigurationProperties("spring.datasource.hikari") can also be used, no difference
    public DataSourceProperties mySQLDataSourceProperties() {
        return new DataSourceProperties();
    }

    @Bean
    @Primary
    @ConfigurationProperties("spring.datasource.hikari")
    public DataSource mySQLDataSource() {
        return mySQLDataSourceProperties().initializeDataSourceBuilder().build();
    }

    @Bean
    @ConfigurationProperties(prefix = "spring.datasource.hikari")
    public HikariConfig hikariConfig() {
        return new HikariConfig();
    }

    @Bean
    public DataSource dataSource() {
        return new HikariDataSource(hikariConfig());
    }

and I had to add these settings in the application.properties:

# this is absolutely mandatory otherwise BeanInstantiationException in mySQLDataSource ! 
spring.datasource.url=${JDBC_CONNECTION_STRING}

spring.datasource.hikari.jdbc-url=${JDBC_CONNECTION_STRING}

spring.datasource.hikari.username=user
spring.datasource.hikari.password=pass